Bio 204 Introduction to Evolution, Ecology, and Biodiversity Alejandro Acevedo Janice Lapsansky Winter 2005

Biology: The Science of Life Why do we study life? How do we study life? … a matter of scale - - size and time Which ideas/concepts guide biologists?

Organizing the Diversity of Life Taxonomy = the process of naming and classifying organisms Three Domains: Bacteria Archaea Eukarya Five Kingdoms: (see figure on next slide)

Themes in the Study of Life Levels of organization: The difference between living and non- living is one of degree, not kind. What does this mean? Cells are an organism’s basic unit of structure and function What is a cell? List one example that illustrates the interdependence of structure and function.

What are some of the main differences between prokaryotic and eukaryotic cells? Fig. 1.4

Fig. 1.2 Levels of Organization

Themes in the Study of Life Emergent Properties Each level of biological organization has emergent properties that result from the interaction of structural and functional components These emergent properties include those characteristics we often use to describe life: metabolism, growth and development, homeostasis, reproduction, and evolutionary adaptation.

Respond to the following statement: “Living things are chemical and physical machines.” Is your current view more in line with holism or reductionism?

Themes in the Study of Life Homeostasis = the maintenance of a dynamic equilibrium Why does an organism’s internal environment change? Why is a stable internal environment important to an organism’s survival? Describe an example. Most homeostatic mechanisms operate as negative feedback loops. Draw the components of a basic negative feedback loop.

Themes in the Study of Life Informational Molecules Some biological macro molecules contain “code” by virtue of the sequence of the building blocks they contain. Name the type of molecule that contains the instructions for maintaining the structure and function of an organism. Name the type of molecule that is made from these instructions. All forms of life use this same code Are there other similarities that unify the diversity of life? Inheritance of traits relies on accurate duplication and transmission of this code to offspring Can organisms change because they “have to” in order to survive in a challenging environment?

Themes in the Study of Life All living things depend directly or indirectly on all other living things for survival Briefly describe how an organism changes its biotic environment….its abiotic environment. Describe the flow of energy and raw materials through the biosphere.

Themes in the Study of Life Evolution is the core theme of biology “descent with modification” Natural selection is one mechanism of evolution Q: Which of the following observations made by Charles Darwin was/were pivotal to the development of his concept of evolution a. Populations never produce more offspring than can be supported by the environment b. Individuals in a population exhibit at least slight differences in their structure and/or function c. Some individuals possess traits that make them more “fit” in their environment d. Human skin cells look exactly like bacterial cells from mineral hot springs

Help Jane with her homework… True or False. Natural selection creates adaptations. Justify your answer.

Themes in the Study of Life Scientific Process …begins with a question one way to acquire knowledge Can any question be answered by the scientific method? 2 basic ways to approach a question: inductive reasoning deductive reasoning

Themes in the Study of Life Inductive Reasoning:  generalize from specific observations example: When is inductive reasoning used in the scientific process? Deductive Reasoning:  propose a model (involving assumptions) that provides a tentative explanation that can be applied to specific situations  requires that evidence be collected to test the model and assumptions

? Hypothesis Test Support Reject modify or abandon repeat What important skills are critical to your ability to formulate hypotheses? When is more than one hypothesis appropriate in science? What is a scientific theory and how is it different from a hypothesis?

Small Group Exercise: An Introduction to Correlation Does smoking cause lung cancer? Does drunk driving cause accidents? Do thin people live longer? You may think you know the answers to some or all of these questions already. On what evidence and/or reasoning to you base your answers? The collection and analysis of data to determine whether two variables are “linked” are important elements in scientific investigations. Finding variables to be linked (i.e. correlated) suggests the possibility of a cause-and-effect relationship. The purpose of this small group exercise is to evaluate information based on the results of scientific research, reported in a newspaper article. Read the article and answer the questions that follow.

Doing poorly: Study links low income with high blood pressure 1. What two variables are correlated according to the article? 2. Is this a direct or inverse correlation? Explain. 3. Does either the author or researcher argue that one of the variables is the cause? Explain