The Science of Biology Chapter 1

2 What are the Properties of Life? Living organisms: Cellular organization- composed of cells Ordered complexity- complex and ordered Sensitivity- respond to their environment Growth, development and reproduction- can grow and reproduce Energy utilization-obtain and use energy Homeostasis-maintain internal balance Evolutionary adaptation-allow for evolutionary adaptation

3 What are the Cellular Levels of Organization? Cellular Organization cells organelles molecules atoms The cell is the basic unit of life.

4 What are the Organism Levels of Organization? Organismal Level organism organ systems organs tissues

5 What are the Population Levels of Organization? Population Level ecosystem community species population

6 What are Emergent Properties? 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 For example: The information present in tissues is not present in a cell but was built on the latter.

7 The Nature of Science Deductive reasoningInductive reasoning General principles Specific predictions of results Specific observations General Scientific Principles Science aims to understand the natural world through observation and reasoning.

8 How hypothesis driven science makes and tests predictions? A systematic approach is used by scientists to gain understanding of the natural world. -Observation -Hypothesis formation -Prediction -Experimentation -Conclusion

9 How hypothesis driven science makes and tests predictions? 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

10 How hypothesis driven science makes and tests predictions? The experiment -tests the hypothesis -must be carefully designed to test only one variable/factor at a time -consists of a test experiment and a control experiment If the hypothesis is valid, the scientist can predict the results and do further experiments to confirm its validity.

11 Other approaches of Science to explain living systems Reductionism (Philosophical approach) - to break a complex process down to its simpler parts -Metabolism of cells were unraveled by understanding individual pathways and their specific enzymes. Models – Provide a way to organize thinking about a problem that is difficult to study directly -Shows a larger picture and how they fit together/interconnect network -Suggests experiments that can refine or test the model

12 What is Scientific Theory? A Scientific Theory -is a body of interconnected concepts -is supported by scientific reasoning and experimental evidence -explains facts in some area of study Research done by scientists is either basic or applied.

13 An example of scientific enquiry by Charles Darwin: His evidence Similarity of related species - Darwin noticed variations in related species living in different locations

14 An example of scientific enquiry by 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

15 Malthus theory of population growth versus resources availability Population growth vs. availability of resources - population growth is geometric - increase in food supply is arithmetic

16 How Darwin’s Evidence enlightened from Malthus theory? 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.

17 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.

18 Post-Darwin Evolution Evidence Comparative anatomy -Homologous structures have same evolutionary origin, but different structure and function. -Example: Forelimbs of different vertebrates responding to their evolutionary demands -Analogous structures have similar structure and function, but different evolutionary origin -Example: Wings of birds and butterflies

19 Post-Darwin Evolution Evidence Molecular Evidence Increased understanding of DNA (genome) and protein (amino acid) structures has led to the development of more accurate phylogenetic trees.

20 Unifying Themes in Biology Cell theory- All living organisms are made of cells, and all living cells come from preexisting cells. Cells process information stored in DNA as well as information received from the environment Molecular basis of inheritance - DNA encodes genes which control living organisms and are passed from one generation to the next.

21 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.

22 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.

23 Unifying Themes in Biology Emergent properties - New properties are present at one level of organization that are not seen in the previous level

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