Your instructor will choose three of the following essay questions for the final exam. You should plan to answer each with about three pages of text and diagrams as appropriate. These questions will count for half of the final exam grade.
1. Using examples, explain the cycling of nutrients, distribution of biomass and energy flow across the trophic levels of an ecosystem. Then, use this ecosystem as a model for explaining the biomagnification of an accumulative hydrophobic contaminant like DDT or PCB.
2. Diagram and explain the role of the E. coli lac operon. Include a detailed description of the process of gene expression in general. What are the main features of the lac repressor and catabolite activator protein in the metabolic control of this pathway? How is this regulation similar and different from regulation of gene expression in eukaryotic cells? Your answer should include a description of regulation of eukaryotic gene expression during development and in response to steroid hormones.
3. Diagram and explain the processes of mitosis and meiosis for a diploid cell with n=2, 2n=4 chromosomes. What are the similarities and differences between these two modes of cell division? What roles do mitosis and meiosis play in human reproduction and development?
4. How does the structure of a mitochondrion influence its function in the cell? Your answer should include, but not be limited to, a diagram of the two mitochondrial membranes as well as the location of proteins involved in pyruvate import, electron transport and ATP synthesis. Explain how mitochondrial structure supports an endosymbiotic origin of this organelle.
5. Explain evolution of species. Your answer should include a detailed description of how new species evolve and how existing species change over time. Make sure you use Hardy -Weinberg equilibrium criteria as well as modes of reproductive isolation in your answer. What evidence exists for evolution? Explain why some people might have difficulty accepting evolution as fact, and why this often stems from a misunderstanding of conclusions that can be drawn from evolution.
6. Using graphs similar to those used in class, use human population to explain the concepts of rate of growth, carrying capacity, and the factors that influence each. Using your description of population growth as background, explain in detail three areas of human impacts that are currently damaging natural systems. What is the likely outcome of these impacts?
7. Explain the similarities and differences between classical Mendelain genetics and molecular biology. Give detailed examples of several problems where each approach might be applied. Include in your answer examples of extensions to Mendelian analysis like incomplete dominance, epistasis, and polyfactorial traits. Which types of genetic questions are not easily answered by either approach?
8. Diagram the structure of
a double-stranded DNA molecule, an mRNA molecule, and a section
of a protein molecule. Explain the role that hydrophobic interactions,
covalent bonds and hydrophobic interactions play in stabilizing
each of these structures. Make sure that your diagram shows the
monomer (repeating unit) of each biological polymer. How is the
structure of each of these molecules suited to its role in the
cell? How does the process of gene expression result in the transfer
of biological information from DNA to protein sequence?
9. Use the main point from the diffusion and osmosis lab exercise (relation of rate of osmosis to steepness of concentration gradient) to explain why countercurrent oxygen / carbon dioxide exchange in fish gills is the more efficient than blood and seawater moving through the gills in the same direction. Include a recap of the results of the diffusion and osmosis lab results, your conclusions, and drawings of the two alternative flows of seawater over gills, as well as an explanation of the advantages of countercurrent exchange.