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Understand the Basic Concepts of Science Balanced Instruction and


									                                                                                                                                                                                                                                                                                                                                                            Understand the Basic Concepts of Science

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            Curriculum Congruency
    Balanced Instruction and Assessment                                                                                                                                                                                                                                                                                                                     Concepts fundamental to each strand in the curriculum are developed with text
                                                                                                                                                                                                                                                                                                                                                            and visual images. Students learn to apply a number of strategies such as using
    • Nelson Science 10 reflects the overall aim of the                                                                                                                                                                                                                                                                                                     headings, reading labels, and interpreting diagrams to assist their understanding
                                                                                                                                                                                                                                                icating • Communi
      secondary science program which is “to ensure                                                                                                                                                                             C   om
                                                                                                                                                                                                                                      mun                                                     cat
                                                                                                                                                                                                                                                                                                     i ng                                                   of concepts. A questions box at the end of each lesson provides a range of
      scientific literacy for every secondary school                                                                                                                                                                  t in                                                                                         o
                                                                                                                                                                                                                                                                                                                                                            questions designed to reinforce and assess students’ understanding, to help



                                 The Ontario Curriculum,                                                                                                                                                                                                                                                                                                    connect the concepts to their applications, and to encourage students to reflect


                                                                                                                                                                                                                                                                                                                               t ing
                                                                        Grades 9 and 10: Science, page 4

                                                                                                                                                                                                         • Co
                                                                                                                                                                                                                     Understanding                                             Developing                                                                   on their learning and explore further.

                                                                                                                                                                                                                                                                                                                                 • C om
                                                                                                                                                                                      mu n i c a t i n g
                                                                                                                                                                                                                       Concepts                                                  Skills
    • Nelson Science 10 addresses 100% of the

                                                                                                                                                                                                                                                                                                                                       mu n i c a t i n g
      Grade 10 Academic course curriculum                                                                                                                                                                                                                                                                                                                                                                                                             CHAPTER

                                                                                                                                                                                • C om
                                                                                                                                                                                                                                                                                                                                                                                                                                                  15 Extreme Weather Events
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     Some of the extreme weather you will learn
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 about occur elsewhere in the world, but many                                 Reflect on your Learning
      expectations.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              happen in Canada. Perhaps such an event has
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 occurred in your area. How would you protect

                                                                                                                                                                                                                                                                                                                          • Co
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              1. List as many examples of dangerous, extreme weather

                                                                                                                                                                                            t ing
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 yourself during such an event?                                                  events as you can. Suggest which is the easiest and

                                                                                                                                                                                                                                                    Relating                                                                                                                                                                                                                                                                                                                                                                         Scientists use modern technology to research
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 extreme weather, and sometimes in surprising
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 which is the most difficult to forecast. Explain your

                                                                                                                                                                                                                                                                                                                                                              The Getting

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 places. For example, satellites and remote sensors                           2. For each of the following regions of Canada, state the
    • Nelson Science 10 provides a balance of
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 gather temperature data and determine

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 extreme weather events you think are most likely to
                                                                                                                                                                                                                                                                                                                                                                                                                                                              Getting Started

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 sea level heights from the Pacific Ocean; this                                  occur. (More than one event may be named for each

                                                                                                                                                                                                                                                                                                                                                              Started chapter
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 information can help scientists understand and                                  region.)

                                                                                                                                                                                                                                                                                                                  t in                                                                                                                                                                                                                                                                                                           predict weather as far away as Central Canada.                                  (a) British Columbia and western Alberta
                                                                                                                                                                                                                      o                                                                                                                                                                                                                                                                                                                                                                                                              Extreme weather events are major news items

      instruction and assessment reflecting the
                                                                                                                                                                                                                                                                                                           g•                                                                                                                                                  HOW STRONG DOES WIND HAVE TO BE TO TOPPLE A GARBAGE CAN?                                                                                                                                                                                          (b) the Prairies
                                                                                                                                                                                                                          •C                                                                        Co                                                                                                                                                         Now imagine winds powerful enough to pick up a truck and toss it the
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 for the media, especially television, which can
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 combine the sounds of horrendous winds or rushing                               (c) the Arctic region
                                                                                                                                                                                                                               i ng                                                                                                                                                                                                                            length of a football field. Winds of this magnitude sometimes happen
                                                                                                                                                                                                                                            icating • Communi
                                                                                                                                                                                                                                                                                        un                                                                    openers                                                                                          in a tornado (Figure 1).
                                                                                                                                                                                                                                                                                                                                                                                                                                                                    A tornado is just one example of an extreme weather event.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 water with the visual images of buildings blown out
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 to sea or people on rooftops of flooded homes
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 waiting to be rescued. Sometimes the media go
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 (d) Ontario and Quebec
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 (e) the Atlantic provinces

      three goals of the curriculum which are:                                                                                                                                                                                                                                                                                                                                                                                                                 In the previous two chapters you studied the main types of weather events.                                                                                                                                                                     3. Which extreme weather events do you think could hit
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 beyond the dramatic visual highlights and try                                   your town or city?

                                                                                                                                                                                                                                                                                                                                                                                                                                                               Now you will learn about the causes and effects of extreme weather events.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 to explain the causes and newest theories of the
                                                                                                                                                                                                                                                                                                                                                                                                                                                               It is during extreme events that records of the greatest winds, most rainfall,                                                                                                                                                                 4. Human activities and natural phenomena can combine
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 extreme weather by interviewing experts. Another
                                                                                                                                                                                                                                                                                                                                                                                                                                                               and deepest snowfall are challenged and sometimes broken.                                                                                                                                                                                         to create a different form of extreme weather event.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 important media role is to warn the public of severe
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 Why do you think some locations get “air quality
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 weather events. Many lives and properties have been

                                                                                                                                                                                                                                                                                                                                                              students to
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 warnings” on certain hot summer days?

      - to understand the basic concepts of science;                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             saved because of warnings of dangerous storms.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              Throughout this chapter note any changes in your ideas as
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              you learn new concepts and develop your skills.

                                                                                                                                                                                                                                                                                                                                                              reflect on
      - to develop the skills, strategies, and habits of mind required for scientific inquiry;                                                                                                                                                                                                                                                                prior learning
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         Try This
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         Activity Dangerous Situations
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      In a group, discuss what actions you would take                     •    You live on a cattle ranch near the banks of a
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      to survive in each situation described below. For                        river whose flooding waters will threaten the

      - to relate science to technology; society, and the environment.”                                                                                                                                                                                                                                                                                       and access
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      each situation, provide a brief summary of your
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      • You are staying at a two-storey hotel on the
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          beach of an ocean, and a hurricane is

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               cattle in a few days.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               You live in a large city where freezing rain is
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               forecast to last for 48 h.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               You are staying at an isolated, rural cottage as
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          approaching.                                                         a blizzard is approaching. You know that last
                                                                       The Ontario Curriculum, Grades 9 and 10: Science, page 4                                                                                                                                                                                                                               existing                                                                                                                                                                                                                                                                • You are at home when you hear a tornado
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          warning on the radio.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      • You are canoeing on a lake, and you hear a
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               winter a similar storm blacked out electricity
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               for a week.

                                                                                                                                                                                                                                                                                                                                                              knowledge of
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          thunderstorm approaching.

    • Nelson Science 10 offers a balance of questions and assessment opportunities                                                                                                                                                                                                                                                                            the topic.                                                                                       Figure 1

      reflecting The Achievement Chart for Science categories (Knowledge/                                                                                                                                                                                                                                                                                                                                                                                     An approaching tornado is a terrifying sight. Notice the funnel shape of the storm cloud.

                                                                                                                                                                                                                                                                                                                                                                                                                                                              578      Chapter 15                                                                                                                                                                                                                                                             Extreme Weather Events 579

      Understanding, Inquiry, Communication, and Making Connections)

      Unit 1 Overview                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              Specific Expectation Addressed:
      Overall Expectations
      In this unit, you will be able to
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   “ – illustrate the cycling of matter through biotic and
      • understand how ecosystems change and how they are sustained;
      • investigate factors that affect ecosystems; and
      • analyze issues that affect the sustainability of ecosystems.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   abiotic components of an ecosystem tracking nitrogen.”
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   The Ontario Curriculum, Grades 9 and 10: Science, 25

                                                                                                                      Chapter 3                                                  Chapter 4                                                                                                                                                                                                                                                                                                                                   Nitrogen Fixation by Bacteria
                                                                                                                      Sustaining Terrestrial Ecosystems                          Sustaining Aquatic Ecosystems                                                                                                                                                                                                                                                                                                               Some bacteria are capable of fixing nitrogen. These bacteria provide the
                                                                                                                      From tundra to desert, from mixed forest to                Canada’s variety extends also to our aquatic                                                                                                                                 The Nitrogen Cycle                                                                                                                                             vast majority of nitrates found in ecosystems. They are found mostly in
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             soil. Nitrogen-fixing bacteria can also be found in small lumps called
                                                                                                                      grassland, Canada supports a wide range of biomes.         ecosystems. Canadians are struggling now with                                                                                                                                                                                                                                                                                               nodules on the roots of legumes such as clover, soybeans, peas, and alfalfa
                                                                                                                      Many factors, both abiotic and biotic, affect which        initiatives to maintain those ecosystems and to                                                                                                                              Life depends on the cycling of nitrogen. Nitrogen atoms are required so                                                                                        (Figure 2). The bacteria provide the plant with a built-in supply of usable
                                                                                                                      species live where.                                        produce sustainable harvests.                                                                                                                                                that cells can make proteins. Nitrogen is also required for the synthesis of                                                                                   nitrogen, while the plant supplies the nitrogen-fixing bacteria with the
                                                                                                                                                                                                                                                                                                                                                              deoxyribonucleic acid or DNA, the hereditary material found in all living                                                                                      sugar they need to make the nitrates. This plant-bacteria combination
      Chapter 1                                                Chapter 2                                              In this chapter, you will be able to                       In this chapter, you will be able to                                                                                                                                         things. The movement of nitrogen through ecosystems, the                                                                                                       usually makes much more nitrate than the plant or bacteria need. The
                                                                                                                                                                                                                                                                                                                                                              soil, and the atmosphere is called the nitrogen cycle.                                                                                                         excess moves into the soil, providing a source of nitrogen for other plants.
      Diversity in Ecosystems                                  Change and Stability in Ecosystems                     • analyze the climate, vegetation, and physical            • explain why aquatic ecosystems respond
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  The traditional agricultural practices of including legumes in crop
                                                                                                                        geography of Canadian biomes, and present the              differently to short-term stresses and long-term                                                                                                                                When you consider that nitrogen gas (N2) composes                                                                                                                                                                                                  Figure 2
      Every living thing is part of a complex web of           Ecosystems often appear unchanging. An untouched                                                                                                                                                                                                                                               nearly 79% of the Earth’s                                                                                                                                      rotation and mixed planting capitalize on bacterial nitrogen fixation.
      relationships that we call an ecosystem. Every species   forest or pond may look much the same now as it          information using spreadsheets, tables, graphs,            changes;                                                                                                                                                                                                                                                                                                                                                                                                                           A clover root. You can see the swollen
                                                                                                                                                                                                                                                                                                                                                              atmosphere, you would                                                                                                                                                                                                                                   nodules where the nitrogen-fixing bacteria
      has a role — if even one species is removed, the         did 40 or 50 years ago. Underneath that surface          and diagrams;                                            • analyze fish populations and explain how                                                                                                                                   think that access to                                                  proteins in                     proteins in                                              Nitrogen and Decomposers                                                                 do their work.
      ecosystem may change.                                    stability, though, great changes are taking place as   • assess the impact on ecosystems of change caused           different factors affect the population size;                                                                                                                              nitrogen would not                   atmospheric                        plants                         animals                                                 All organisms produce wastes and eventually die. When they do, a series of
                                                               matter cycles and energy flows through the system.       by natural events, and by the technologies of            • identify and evaluate Canadian initiatives to                                                                                                                              be a problem for                       nitrogen
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             decomposers break down the nitrogen-containing chemicals in the waste
      In this chapter, you will be able to                                                                              agriculture, forestry, and industry;                       protect the Great Lakes;                                                                                                                                                   organisms.                                         nitrites
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             or body into simpler chemicals such as ammonia (NH3). Other bacteria
                                                               In this chapter, you will be able to                   • explain how the fertility of soil can be altered and     • describe and investigate the physical and                                                                                                                                  Unfortunately,                                                                                                                                                 convert ammonia into nitrites, and still others convert the nitrites into
      • examine the factors (natural and external) that                                                                                                                                                                                                                                                                                                                                                                                                                           excretions
                                                                                                                        the consequences of such changes;                          chemical processes involved in cleaning up                                                                                                                                 this is not the                                              nitrates                                                                                          nitrates. These bacteria all require oxygen to function. The nitrates then
        affect the survival of species such as frogs and       • describe how carbon, oxygen, nitrogen, and                                                                                                                                                                                                                                                   case. Nitrogen
                                                                                                                                                                                                                                                                                                                                                                                      nitrogen                                                        death
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             continue the cycle when they are absorbed by plant roots and converted
                                                                                                                      • research the effects of potato farming and                 contamination in the Great Lakes and in the                                                                                                                                                         fixing                               (NO3)                 decomposition
        eagles, and that affect the balance of ecosystems;       phosphorus cycle through ecosystems;                                                                                                                                                                                                                                                         gas is a very           bacteria                                                                                                                               into cell proteins and DNA.
                                                                                                                        propose a course of action that takes into account         oceans;
      • create a database of endangered Canadian species;      • explain how pesticides move through food webs                                                                                                                                                                                                                                                stable molecule,                                                                                                                                                   Farmers and gardeners who use manure and other decaying matter
                                                                                                                        human and environmental needs;                           • describe how the relationships between

      • investigate how abiotic factors, such as sunlight        in the Great Lakes, on the Prairies, and in the                                                                                                                                                                                                                                                                                                                                                                  ammonia
                                                                                                                                                                                                                                                                                                                                                              and reacts only

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             take advantage of the nitrogen cycle. Soil bacteria convert the
                                                                                                                      • identify and analyze major threats to ecosystems           organisms and their ecosystems are viewed                                                                                                                                                                                                                                                       (NH3)

        and moisture, affect a nonnatural ecosystem              forests of Atlantic Canada, and assess how the                                                                                                                                                                                                                                               under limited                                                                                                                                                  decomposing protein in the manure into nitrates. Eventually, the nitrates

                                                                                                                        worldwide;                                                 by various cultures.                                                                                                                                                                                                        CA

        (a park) and a natural system (a meadow), and            pesticides affect organisms in those food webs;                                                                                                                                                                                                                                              conditions. To be                    NITRIFI                          AT                                                                                       are absorbed by plants.

                                                                                                                      • design and conduct an investigation into the                                                                                                                                                                                          useful to organisms
        suggest ways of assuring the continuation of           • analyze how the growth of populations (such as                                                                                                                                                                                                                                                                                                                        IO
                                                                                                                        effects of acid rain.                                                                                                                                                                                                                 nitrogen must be                                                             N             nitrogen fixing                                                     Denitrification
        those ecosystems;                                        deer, wolves, or humans) is limited by available                                                                                                                                                                                                                                                                                                                                            bacteria
                                                                                                                                                                                                                                                                                                                                                              supplied in another form,                                                                                                                                      At various stages in the decay process, denitrifying bacteria can break
      • examine how abiotic factors affect the survival          resources and other factors;
                                                                                                                                                                                                                                                                                                                                                              the nitrate ion (NO3–).                             nitrate loss                                                                                               down nitrates into nitrites, and then nitrites into nitrogen gas. Eventually,
        and location of populations.                           • analyze the benefits and risks of spraying                                                                                                                                                                                                                                                        The nitrogen cycle is exceptionally          from leaching                                                                                                the nitrogen gas is released back into the atmosphere. This process, called
                                                                 pesticides to control caterpillars.                                                                                                                                                                                                                                                          complex. The simplified description in                                                                                                                         denitrification, is carried out by bacteria that do not require oxygen.
                                                                                                                                                                                                                                                                                                                                                              Figure 1 shows two ways in which atmospheric                                                                                                                   Denitrification ensures the balance among soil nitrates, nitrites, and                Figure 3
                                                                                                                                                                                                                                                                                                                                                              nitrogen can be converted into nitrates, in a process called nitrogen                    Figure 1
      4   Unit 1                                                                                                                                                                                                                 Sustaining Ecosystems 5                                                                                                                                                                                                                                                                     atmospheric nitrogen, and completes the nitrogen cycle.                              Plants that grow in nitrogen-poor soils
                                                                                                                                                                                                                                                                                                                                                              fixation. The first method is lightning, and the second is bacteria                     Like carbon, nitrogen moves in a cycle                                                                                                                      can form only a limited amount of
                                                                                                                                                                                                                                                                                                                                                                                                                                                      through ecosystems, passing through                                         Older lawns often have many denitrifying bacteria. The fact that
                                                                                                                                                                                                                                                                                                                                                              in the soil.                                                                                                                                                                                                                                        chlorophyll. The yellowness of this
                                                                                                                                                                                                                                                                                                                                                                                                                                                      food chains and from living things to                                  denitrifying bacteria grow best where there is no oxygen may help to                 plant’s leaves indicates that the plant is
                                                                                                                                                                                                                                                                                                                                                                                                                                                      their environment and back again.                                      explain why gardeners often aerate their lawns in early spring. By exposing          starving for nitrogen.
                                                                                                                                                                                                                                                                                                                                                              Nitrogen Fixation by Lightning                                                                                                                                 the denitrifying bacteria to oxygen, the breakdown of nitrates into
                                                                                                                                                                                                                                                                                                                                                              A small amount of nitrogen is fixed into nitrates by lightning. The energy                                                                                     nitrogen gas is reduced. Nitrates will then remain in the soil, where they
                                                                                                                                                                                                                                                                                                                                                              from the lightning causes nitrogen gas to react with oxygen in the air,                                                                                        can be drawn in by grass roots and used to make proteins.
                                                                                                                                                                                                                                                                                                                                                              producing nitrates. The nitrates dissolve in rain or surface water, enter                                                                                           This information may also help you understand why the leaves of
                                                                                                                                                                                                                                                                                                                                                              the soil, and then move into plants through their roots. Plant cells can                                                                                       some plants may not be a rich green colour. Chlorophyll is a protein,
                                                                                                                                                                                                                                                                                                                                                              use nitrates to make DNA, and they can convert nitrates into amino acids,                                                                                      and plants require nitrates to make it. The colour of a plant’s leaves may
                                                                                                                                                                                                                                                                                                                                                              which they then string together to make proteins. When a plant is                                                                                              tell you the nitrate content of the soil (Figure 3).
                                                                                                                                                                                                                                                                                                                                                              consumed by animals, the animal breaks down the plant proteins into                                                                                                 The denitrification process speeds up when the soil is very acid or
                                                                                                                                                                                                                                                                                                                                                              amino acids and then can use the amino acids to make the proteins it needs.                                                                                    water-logged (oxygen content is low). Bogs, for example, are well known

                            The Unit Overview describes the key                                                                                                           Chapter 8 Summary                                                                                                                                                                                                                                                                                                                                  for their lack of useful nitrogen. They can support only a few types of
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             plants — those able to live with low levels of nitrogen. Insect-eating
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             plants, such as sundews and pitcher plants (Figure 4), are commonly            Figure 4
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             found in bogs. In an interesting reversal of roles, these plants obtain their Insect-eating plants like this pitcher plant, a
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             nitrogen by digesting trapped animals.

                            student expectations for the unit.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           native of Ontario, can grow in nitrogen-poor soil.
                                                                                                                                                                          Key Expectations                                                            • Design an experiment to determine qualitatively the
                                                                                                                                                                          Throughout the chapter, you have had opportunities to                         factors that influence the rate of a reaction. (8.8)
                                                                                                                                                                                                                                                                                                                                                              66 Chapter 2                                                                                                                                                                                                                                           Change and Stability in Ecosystems 67
                                                                                                                                                                          do the following things:                                                    • Describe acid-base neutralization by observing acid-
                                                                                                                                                                                                                                                        base reactions. (8.9, 8.10, 8.11)

                            Curricular expectations are synthesized
                                                                                                                                                                          • Explain the interrelationships between metals and
                                                                                                                                                                            nonmetals, acidic and basic oxides, and acids, bases,                     • Explore careers based on technologies that use                                                                                                                                                            The Phosphorus Cycle
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     Understanding Concepts                                               12. The phosphorus cycle has been described as having two
                                                                                                                                                                            salts. (8.1, 8.2, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 8.10)                       chemical reactions. (8.13)                                                                                                                                                                                Phosphorus is a key element in cell membranes, in molecules that help                                                                                                                                                                       components — a long cycle and a short cycle. The carbon
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  release chemical energy, in the making of the long molecules of DNA, and                                                                                           1. Explain why nitrogen is important to organisms.
                                                                                                                                                                          • Use appropriate apparatus and apply WHMIS safety                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  cycle can be described the same way. Draw a diagram that
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  in the calcium phosphate of bones. Phosphorus tends to cycle in two ways:

                            into an easy to understand “student
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     2. If nearly 79% of the atmosphere is nitrogen, how could                splits the carbon cycle into “short” and “long”components.
                                                                                                                                                                            procedures for handling, storage, disposal, and                           Key Terms                                                                                                                                                                                                   a long-term cycle involving the rocks of the Earth’s crust, and a short-term                                                                                          there be a shortage of nitrogen in some soils?
                                                                                                                                                                            recycling of materials in the lab. (8.1, 8.4, 8.5, 8.8, 8.9,
                                                                                                                                                                                                                                                      acid                                 metal oxide                                                                                                                                                            cycle involving living organisms (Figure 5).                                                                                                                       3. How do animals obtain usable nitrogen?                            Making Connections
                                                                                                                                                                                                                                                      acid precipitation                   neutralization                                                                                                                                                              Living things divert phosphates from the normal (long) rock cycle.                                                                                                                                                                 13. With each grain harvest, nitrogen is removed from the
                                                                                                                                                                          • Describe experimental procedures in the form of a lab                                                                                                                                                                                                                                                                                                                                                                                                    4. Nitrogen-fixing bacteria are found in the roots of bean
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  Phosphorus is found in bedrock in the form of phosphate ions (PO43–),

                            language” format.                                                                                                                               report. (8.1, 8.4, 8.5, 8.8, 8.9, 8.11)
                                                                                                                                                                          • Use appropriate vocabulary, SI units, tables, and
                                                                                                                                                                            descriptions of procedures using the scientific
                                                                                                                                                                                                                                                      acidic oxide
                                                                                                                                                                                                                                                                                           nonmetal oxide
                                                                                                                                                                                                                                                                                           pH scale
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  combined with a variety of elements. Phosphates are soluble in water and
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  so can be dissolved out of rock. While dissolved, phosphates can be
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  absorbed by photosynthetic organisms and so pass into food chains.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        plants. Explain how the bacteria benefit the plant and how
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        the plant benefits the bacteria.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     5. Draw a diagram of the nitrogen cycle for a farm or garden
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              field. Farmers have traditionally rotated the crops they
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              plant in each field. A wheat crop was often followed by a
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              legume crop. Because legumes support nitrogen-fixing
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              bacteria, soil nitrogen levels are replenished. The use of
                                                                                                                                                                            method. (8.1, 8.4, 8.8, 8.9, 8.11)                                                                                                                                                                                                                                                         Phosphates eroded from rock are also carried by water from the land                                                                                              where manure is used.
                                                                                                                                                                                                                                                      base                                 salt                                                                                                                                                                                                                                                                                                                                                                                                               nitrogen-rich fertilizers has allowed farmers to abandon
                                                                                                                                                                          • Conduct an experiment to determine the acidity and                                                                                                                                                                                                                                    to rivers, and then to the oceans. In the ocean, phosphates are absorbed by                                                                                        6. Explain why it is a good practice to aerate lawns.                    crop rotation.
                                                                                                                                                                                                                                                      basic oxide                          titration                                                                                                                                                              algae and other plants, where they can enter food chains. Animals use
                                                                                                                                                                            basicity of common household substances. (8.1, 8.4,                                                                                                                                                                                                                                                                                                                                                                                                      7. Explain why phosphorus is important to living things.                 (a) What advantages are gained from planting wheat year
                                                                                                                                                                            8.5)                                                                      indicator                            universal indicator                                                                                                                                                    phosphates to make bones and shells. When they die, these hard remains                                                                                                                                                                          after year?
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     8. Some farmers alternate crops that require rich supplies of
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  form deposits on the ocean floor. Covered with sediment, the deposits
                                                                                                                                                                          • Recognize the relationships between chemical                                                                                                                                                                                                                                                                                                                            Figure 5
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        nitrogen, such as corn, with alfalfa. Alfalfa is usually less         (b) New strains of crops have been especially bred to take
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  eventually become rock, ready to be brought to the surface again. The                                                                                                 valuable in the marketplace than corn. Why would farmers
                                                                                                                                                                            formulas, composition, and names. (8.2, 8.6, 8.7, 8.10,                                                                                                                                                                                                                                                                                                                Phosphates cycle in both long and                                                                                                                              up high levels of nitrogen. These strains produce more
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  cycle can take millions of years to complete.                                                                                                                         plant a crop that provides less economic value?                           grain. Speculate about some possible long-term
                                                                                                                                                                            8.12)                                                                                                                                                                                                                                                                                      In the short cycle, wastes from living
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   short cycles
                                                                                                                                                                          • Describe how the pH scale is used to determine the
                                                                                                                                                                                                                                                           Make a Summary                                                                                                                                                                                                                                                                                                                                                            9. Explain why bogs and swamps are usually low in nitrogen.                  disadvantages that these crops might present for
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  things are recycled by decomposers,                                                                                                                                                                                                             ecosystems.
                                                                                                                                                                            acidity of solutions. (8.3, 8.4)                                               Make a concept map to summarize what you have                                                                                                                                                          which break down wastes and dead                                                                                                                                   10. Speculate about why clover would begin to grow in an
                                                                                                                                                                                                                                                           learned about acids and bases.                                                                                                                                                                         tissue and release the phosphates. The                                                                                                                                 older lawn. How would the presence of clover benefit the
                                                                                                                                                                          • Analyze data and information, evaluate evidence and                                                                                                                                                                                                                                                                                                                                                                                                                                                                           Reflecting
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                phosphate in rocks                                                                                       lawn?
                                                                                                                                                                            sources of information, and identify errors and bias.                                                                                                                                                                                                                                 short cycle is much more rapid.                                  and fossils                                                                                                                                                            14. Crop rotation is an effective way of restoring nitrogen to
                                                                                                                                                                            (8.3, 8.4, 8.5, 8.7, 8.8, 8.11)                                                                                                                                                                                                                                                                                                                                                                                                                          11. Nitrate levels were analyzed from living material and soil           the soil, however, the planting of legumes is not always
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  Variations in Nutrient                                                                                                                                                 samples in three different ecosystems (grassland,                    popular with farmers. Legume crops may provide less
                                                                                                                                                                          • Plan and conduct an inquiry into chemical processes
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         temperate rainforest, and tropical rainforest) in the same           income, because they are more difficult to tend, more
                                                                                                                                                                            using a range of tools, controlling variables, and                                                                                                                                                                                                                                    Cycling
                                                                                                                                                                            adapting or extending procedures where required.                               Reflect on your Learning                                                                                                                                                                               Nitrates and phosphates are both
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     weathering                                                                          month. To determine the mass of nitrates in living things,           costly to plant, difficult to harvest, or worth less in the

      The Chapter-ending Summary feature lists the
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         all living plant matter was collected in a study area and the        marketplace. Farmers must continually balance short-term
                                                                                                                                                                            (8.4, 8.8, 8.9, 8.11)                                                                                                                                                                                                                                                                 nutrients. Nutrients are chemicals that                                                                                                                                levels of nitrates were determined. The same analysis was
                                                                                                                                                                                                                                                           Revisit your answers to the Reflect on your Learning                                                                                                                                                                                                                                                                                                                                                                                               gains and long-term results in this way. Provide some
                                                                                                                                                                          • Formulate questions about practical problems and                                                                                                                                                                                                                                      are essential to living things. The rate                                                                                                                               conducted for the top layer of soil. The results are listed in       examples of how you balance short-term gains with long-
                                                                                                                                                                            issues involving chemical processes. (8.5, 8.7, 8.8, 8.9,                      questions, p. 289, in the Getting Started.                                                                                                                                                             with which nutrients cycle through an                                          dissolved inorganic                                                                     Table 1, where each ecosystem is identified by a number.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                phosphate (soil, rivers)                                                                                                                                      term results in decisions that you make.
                                                                                                                                                                            8.11)                                                                          • How has your thinking changed?                                                                                                                                                                       ecosystem is linked to the rate of

      specific “Key Expectations” addressed, and                                                                                                                          • Represent chemical reactions using models, word
                                                                                                                                                                            equations, and balanced chemical equations. (8.2, 8.5,
                                                                                                                                                                            8.6, 8.8, 8.9, 8.11)
                                                                                                                                                                                                                                                           • What new questions do you have?
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  decomposition. Organic matter
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  decomposes relatively quickly in the
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  tropical rainforests. Warmth, moist soil,
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  and the vast number of diverse and
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    phosphate in
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  phosphate in
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          Table 1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       Nitrate Content of Three Ecosystems
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      Soil nitrates Biomass nitrates
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      (kg/hectare)    (kg/hectare)
                                                                                                                                                                          • Explain how environmental challenges can be

      point to where the expectations have been                                                                                                                             addressed through an understanding of chemical
                                                                                                                                                                            substances. (8.6, 8.7, 8.8, 8,12)
                                                                                                                                                                          • Select and integrate information from many sources
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  specialized decomposers permit a cycle
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  to be complete in as little as a few
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  months. Cycling in cooler forests takes
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  an average of between four and six
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  runoff to

      addressed in the chapter. The expectations                                                                                                                            including electronic, print, and community resources,
                                                                                                                                                                            and personally collected data. (8.7, 8.12)
                                                                                                                                                                          • Describe how an understanding of chemical reactions
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  years. In the even cooler tundra,
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  nutrient cycling takes up to 50 years. In
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  the oxygen-poor environment of most
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  lakes, cycling may take even longer.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  bones, teeth,
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         (a) In which community does nitrogen cycle most rapidly?
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             Explain your conclusion.
                                                                                                                                                                            has led to new consumer products and technological                                                                                                                                                                                                                                                                                                                                                                                                           (b) Which ecosystem (grassland, temperate rainforest,

      are expressed in the same language that is                                                                                                                            processes. (8.7, 8.11, 8.12)
                                                                                                                                                                          • Conduct an experiment on the combustion of metals
                                                                                                                                                                            and nonmetals, and react the oxides formed with
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  Temperature and oxygen levels are the
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  two most important abiotic factors
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  regulating decomposition. Other
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  factors, such as soil chemistry and the
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   sediments                                                 and tropical rainforest) is study area 1, 2, and 3? Give
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             reasons for your answers.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         (c) Speculate about the data that might be collected from
                                                                                                                                                                            water to produce an acid or a base. (8.5)

      used in the curriculum document.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             a tundra ecosystem (Figure 6). Explain your prediction.            Figure 6
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  frequency of fire, also affect
                                                                                                                                                                                                                                                                                                                                                                                                                                                                  decomposition and cycling.

                                                                                                                                                                                                                                                                                                   Acids and Bases 325                                                                                                                                            68   Chapter 2                                                                                                                                                                                                                                                    Change and Stability in Ecosystems 69

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