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									Dr. Adam Safer BS Armstrong Atlantic State University MS Georgia Southern University PhD Florida Institute of Technology

About Me

Mechanisms of infrared imaging in snakes

Kin recognition among reptiles

Ecology of reptiles and amphibians of the Southeastern United States

The Science of Biology
Chapter 1

Properties of Life
Living organisms: – are composed of cells – are complex and ordered – respond to their environment – can grow and reproduce – obtain and use energy – maintain internal balance – allow for evolutionary adaptation
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How to Define Life
Living Things Are Organized
• • • • • • • • • • • • Organization of living systems begins with atoms, which make up basic building blocks called elements. The cell is the basic structural and functional unit of all living things. Different cells combine to make up tissues (e.g., myocardial tissue). Tissues combine to make up an organ (e.g., the heart). Specific organs work together as a system (e.g., the heart, arteries, veins, etc.). Multicellular organisms (each an “individual” within a particular species) contain organ systems (e.g., cardiovascular, digestive, respiratory, etc.). A species in a particular area (e.g., gray squirrels in a forest) constitutes a population. Interacting populations in a particular area comprise a community. A community plus its physical environment is an ecosystem. The biosphere is comprised of regions of the Earth’s crust, waters, and atmosphere inhabited by organisms. Each level of organization is more complex than the level preceding it. Each level of organization has emergent properties due to interactions between the parts making up the whole; all emergent properties follow the laws of physics and chemistry.
– Emergent property quality that appears as biological complexity increases 6

Levels of Organization
Cellular Organization

cells
organelles molecules

atoms
The cell is the basic unit of life.
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Levels of Organization
Organismal Level

organism
organ systems organs tissues

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Levels of Organization
Population Level

ecosystem community
species population

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Levels of Organization
Each level of organization builds on the level below it but often demonstrates new features.

Emergent properties: new properties present at one level that are not seen in the previous level

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Living Things Acquire Materials and Energy
• Maintaining organization and conducting life-sustaining processes require an outside source of energy, defined as the capacity to do “work.” • The ultimate source of energy for nearly all life on earth is the sun; plants and certain other organisms convert solar energy into chemical energy by the process of photosynthesis. • Food provides nutrient molecules used as building blocks for energy. • Metabolism is all the chemical reactions that occur in a cell. • All organisms must maintain a state of biological balance, or homeostasis. Temperature, moisture level, pH, etc. must be maintained within the tolerance range of the organism. Organisms have intricate feedback and control mechanisms to maintain homeostatic balance.

extension.oregonstate.edu

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www.valdosta.edu

Living Things Respond
• Living things interact with the environment and with other living things. • Response often results in movement of the organism (e.g., a plant bending toward the sun to capture solar energy, a turtle withdrawing into its shell for safety, etc.). • Responses help ensure survival of the organism and allow the organism to carry out its biological activities. • The collective responses of an organism constitute the behavior of the organism.

www.pitt.edu

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Living Things Reproduce and Develop • Reproduction is the ability of every type of organism to give rise to another organism like itself. • Bacteria, protozoans, and other unicellular organisms simply split in two (binary fission). • Multicellular organisms often unite sperm and egg, each from a different individual, resulting in an immature individual which develops into the adult. • The instructions for an organism’s organization and development are encoded in genes. • Genes are comprised of long molecules of DNA (deoxyribonucleic acid); DNA is the genetic code in all living things.

www.ericolson.addr.com

www.micro.utexas.edu

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Living Things Have Adaptations • Adaptations are modifications that make organisms suited to their way of life. • Natural selection is the process by which species become modified over time.
– A species is a group of interbreeding individuals. – In natural selection, members of a species may inherit a genetic change that makes them better suited to a particular environment. – These members would be more likely to produce higher numbers of surviving offspring.

• Evolution is defined as “descent with modification over time.”
– The fact that all life forms are composed of cells, contain genes comprised of DNA, and conduct the same metabolic reactions suggests all living things have a common ancestor. – One species can give rise to several species, each adapted to to a particular set of environmental conditions. – Evolution is responsible for the great diversity of life on Earth.

www.podfeed.net

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How the Biosphere is Organized
Levels of Complexity • The biosphere is the zone of air, land, and water where organisms exist. • A population consists of all members of one species in a particular area. • A community consists of all of the local interacting populations. • An ecosystem includes all aspects of a living community and the physical environment (soil, atmosphere, etc.). • Interactions between various food chains make up a food web. • Ecosystems are characterized by chemical cycling and energy flow. • Ecosystems stay in existence because of a constant input of solar energy and the ability of photosynthetic organisms to absorb it. 15

The Human Population • The human population modifies existing ecosystems for its own purposes. • Two biologically diverse ecosystems, rain forests and coral reefs, are severely threatened by the human population. • Human beings depend on healthy working ecosystems for food, medicines, and raw materials.

www.aims.gov.au/monmap/aesthetics/aes18031Sb.html

www.hickerphoto.com

www.fisheyeview.com

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www.casarioblanco.com

The Nature of Science
Science aims to understand the natural world through observation and reasoning. Science begins with observations, therefore, much of science is purely descriptive. Science uses both deductive and inductive reasoning.
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The Nature of Science
Deductive reasoning uses general principles to make specific predictions. Inductive reasoning uses specific observations to develop general conclusions.

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Inductive and Deductive Reasoning
• Deductive Reasoning
– Proceeds from generalities to specifics – Adds nothing new to knowledge, but makes relationships among data more apparent – Ex:
• GENERAL RULE: All birds have wings • SPECIFIC EXAMPLE: Robins are birds • CONCLUSION (based on deductive reasoning): All Robins have wings

Inductive and Deductive Reasoning
• Inductive Reasoning
– Used to discover general principles – Seeks a unifying explanation for all the data available – Ex:
• • • • FACT: Gold is a metal heavier than water FACT: Iron is metal heavier than water FACT: Silver is a metal heavier than water CONCLUSION (based on inductive reasoning): All metals are heavier than water

– Conclusions reached with inductive reasoning may changed with new information

The Nature of Science
Scientists use a systematic approach to gain understanding of the natural world. -Observation -Hypothesis formation -Prediction -Experimentation -Conclusion
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The Nature of Science
A hypothesis is a possible explanation for an observation. A hypothesis -must be tested to determine its validity -is often tested in many different ways -allows for predictions to be made
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The Nature of Science
The experiment -tests the hypothesis -must be carefully designed to test only one variable at a time -consists of a test experiment and a control experiment

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The Nature of Science
If the hypothesis is valid, the scientist can predict the result of the experiment. Conducting the experiment to determine if it yields the predicted result is one way to test the validity of the experiment.

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The Nature of Science
Scientists may use reductionism - to break a complex process down to its simpler parts

models – to simulate phenomena that are difficult to study directly

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The Nature of Science
A scientific theory -is a body of interconnected concepts -is supported by much experimental evidence and scientific reasoning -expresses ideas of which we are most certain

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Charles Darwin
Served as naturalist on mapping expedition around coastal South America. Used many observations to develop his ideas Proposed that evolution occurs by natural selection
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Voyage of the Beagle

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Charles Darwin
evolution: modification of a species over generations -“descent with modification”

natural selection: individuals with superior physical or behavioral characteristics are more likely to survive and reproduce than those without such characteristics
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Darwin’s Evidence
Similarity of related species - Darwin noticed variations in related species living in different locations

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Darwin’s Evidence
Population growth vs. availability of resources -population growth is geometric -increase in food supply is arithmetic
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Darwin’s Evidence
Population growth vs. availability of resources - Darwin realized that not all members of a population survive and reproduce. -Darwin based these ideas on the writings of Thomas Malthus.
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Post-Darwin Evolution Evidence
Fossil record - New fossils are found all the time - Earth is older than previously believed Mechanisms of heredity - Early criticism of Darwin’s ideas were resolved by Mendel’s theories for genetic inheritance.
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Post-Darwin Evolution Evidence
Comparative anatomy - Homologous structures have same evolutionary origin, but different structure and function. - Analogous structures have similar structure and function, but different evolutionary origin.
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Homologous Structures

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Post-Darwin Evolution Evidence
Molecular Evidence - Our increased understanding of DNA and protein structures has led to the development of more accurate phylogenetic trees.
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Unifying Themes in Biology
Cell theory - All living organisms are made of cells, and all living cells come from preexisting cells.

Molecular basis of inheritance - DNA encodes genes which control living organisms and are passed from one generation to the next.
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Unifying Themes in Biology
Structure and Function -The proper function of a molecule is dependent on its structure. -The structure of a molecule can often tell us about its function.

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Unifying Themes in Biology
Evolutionary change - Living organisms have evolved from the same origin event. The diversity of life is the result of evolutionary change. Evolutionary conservation - Critical characteristics of early organisms are preserved and passed on to future generations. 40

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Unifying Themes in Biology
Cells - information processing systems - Cells process information stored in DNA as well as information received from the environment. Emergent properties - New properties are present at one level of organization that are not seen in the previous level.
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