Chapter1 Living Things Notes by PSVCtU


									Chapter 1: Living Things                                     10/8/2009 6:43:00 PM

 What is Life?
 The Characteristics of Living Things
           Organisms: any living thing

             Six Characteristics of a Living Thing:
                  1.) Cellular Organization
                  2.) Contain Similar Chemicals
                  3.) Use Energy
                  4.) Responds to Surroundings
                   5.) Grow and Develop
                   6.) Reproduce

      Cellular Organization
            Cell: basic unit of structure and function in an organism

            Tiny; very small

            Unicellular: a single-celled organism
            example: bacteria

            Multicellular: organisms that are composed of many cells
            example: humans, animals

            Cells have specific jobs (muscles, skin, brain,etc)

      The Chemicals of Life

            Examples: water (most abundant), carbohydrates, proteins,
                 lipids, and nucleic acids

            Cells are all composed of chemicals

      Energy Use
            Cells are always working

            Example: blood cells are moving chemicals around, stomach
            cells are digesting food

      Responds to Surroundings
           Stimulus: causes an organism to react
           example: temperature, light, sound

            Response: an action or a change in behavior
            example: jumping, screaming, flintching

      Growth & Development
           Growth is the process of becoming larger

            Development: process of change that occurs during an
                 organism's life to produce a more complex organism

            Use energy to create new cells

           Produce offspring that are similar to parents

Life Comes From Life
           Living things arise from living things through reproduction

            Spontaneous generation: the mistaken idea that living things arise
            from nonliving sources

      Redi’s Experiment
            In the 1600’s an Italian doctor named Fancesco Redi disproved
            spontaneous generation using a controlled experiment

            Controlled experiment: an experiment in which all factors are
            identical except one
              Redi used two jars, both with slabs of meat in them, covered one
              and not the other- the one without the cover had maggots/flies on
              it, and the one with the cover did not have anything

      Pasteur’s Experiment
           Many people still did not believe Redi’s experiment so in the mid-
           1800’s a French chemist Louis Pasteur set out to prove Redi was

              Pasteur used broth, boiled one and not the other, and put them in
              flasks- the boiled one did not have any bacteria, but the non-boiled
              one had a lot

The Needs of Living Things
           All living things must satisfy their basic needs for food, water,
           living space, and stable internal conditions

              The food organisms use is their energy source

              Autotroph: an organism that makes it own food
              (example: plants, trees)

              Heterotroph: an organism that cannot make its own food
              (example: humans, mushrooms, animals)

              Some heterotrohps eat autotrophs, others eat other heterotrophs

              Organisms need water to obtain chemicals from their surroundings,
              break down food, grow, move substances within their bodies, and

      Living Space
            All organisms need a place to live- a place to get food and water
            and find shelter
               An organisms surroundings must provide what it needs to survive

               Because there is limited space on Earth, some organisms have to
               compete for space

       Stable Internal Conditions
             Your body needs to maintain a stable temperature so your cells can
             carry out their every day functions

               Homeostasis: the maintenance of stable internal conditions

               Humans sweat and shiver to help maintain a stable internal

Classifying Organisms
Why Do Scientists Classify?
           Biologists group organisms based on similarities

               Classification: the process of grouping things based on their

               Biologists use classification to organize living things into groups so
               that the organisms are easier to study

               Taxonomy: the scientific study of how things are classified

               Taxonomy is useful because once an organism is classified, a
               scientist knows a lot about that organism

       The Naming System of Linnaeus
            In the 1750’s a Swedish naturalist Carolus Linnaeus came up with a
            system for naming organisms

               Linnaeus placed organisms in groups based on their observable
            Each organism was given a unique, two-part scientific name

            Binomial nomenclature: the system for naming organisms in which
            each organism is given a unique, two-part scientific name indicating
            its genus and species

      Genus and Species
           The first word in an organism’s scientific name is its genus

            Genus: a classification grouping that consists of a number of
            similar, closely related species

            The second word in a scientific name often describes a distinctive
            feature of an organism

            Together, the two words indicate a unique species

            Species: a group of similar organisms that can mate with each
            other and produce offspring that can also mate and reproduce

      Using Binomial Nomenclature
            This naming system makes it easier for scientists to communicate
            about an organism because everyone uses the same scientific name
            for the same organism

Levels of Classification

      The Major Levels of Classification
           Organisms are grouped by their shared characteristics

            Kingdom (largest)
          Species (smallest)
        The more classification levels that two organisms share, the more
        characteristics they have in common

 Taxonomic Keys
       Two ways to identify an organism are:
       1.) Field Guide
           A book with illustrations that highlight differences between
               similar-looking organisms
        2.) Taxonomic Keys
            Consists of a series of paired statements that describe the physical
            characteristics of different organisms

Domains and Kingdoms
       There are three domains:
            1. Bacteria
             2. Archaea
             3. Eukarya

        Organisms are placed into domains and kingdoms based on their cell
        type, their ability to make food, and the number of cells in their

  Domain Bacteria
          Prokaryotes: organisms whose cells lack a nucleus

           Nucleus: a dense area in a cell that contains nucleic acids- the
           chemical instructions that direct the cell’s activities

           Some bacteria are autrophs, while others are heterotrophs

           All bacteria are unicellular
           Most bacteria are good, but some are harmful

Domain Archaea
          Tiny organisms that live in the most extreme environments on Earth

           Unicellular prokaryotes, some are heterotrophs and some are

           Although bacteria and archaea are similar in some ways, there are
           important differences in the structure and chemical makeup of
           their cells

Domain Eukarya
          Eukaryotes: organisms with cells that contain nuclei

           Scientists classify organisms in the domain Eukarya into one of
           four kingdoms:

        Any eukaryotic organism that cannot be classified as an animal, plant,
        or fungus

        Often called the “odds and ends” kingdom

        Some are autotrophs, some heterotrophs; some are unicellular, some
        are multicellular

        Examples: mushrooms, molds, mildew
   Most are multicellular eukaryotes

   All are heterotrophs

   All multicellular eukaryotes, autotrophs, and most live on land

   Very wide variety of them

   All animals are multicellular eukaryotes, heterotrophs

   Live in diverse environments throughout the Earth

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