BIOL 110 Exam Review: Cells, Genetics, Evolution and Biodiversity

Terms in this set (30)

1. Prokaryotic vs eukaryotic cellsProkaryotes (bacteria, archaea) lack a nucleus and membrane-bound organelles. Eukaryotes (plants, animals, fungi, protists) have a nucleus and organelles like mitochondria.
2. What is the function of the mitochondrion?It carries out cellular respiration, producing most of the cell's ATP. It has its own DNA, supporting endosymbiotic origin.
3. What is the endosymbiotic theory?Mitochondria and chloroplasts descend from free-living prokaryotes engulfed by an ancestral cell. Evidence: double membranes, own circular DNA and bacteria-like ribosomes.
4. Describe the fluid mosaic model of the plasma membrane.The membrane is a phospholipid bilayer with hydrophobic tails inward, in which proteins, cholesterol and other molecules move laterally like a mosaic.
5. Diffusion vs osmosis vs active transportDiffusion: solutes move down their concentration gradient. Osmosis: water moves across a selectively permeable membrane. Active transport uses energy (ATP) to move solutes against a gradient.
6. What happens to an animal cell in a hypotonic solution?Water enters by osmosis because the outside has lower solute concentration; the cell swells and may lyse.
7. How do enzymes speed up reactions?They lower the activation energy by binding substrates at the active site; they are not consumed and do not change the reaction's overall delta G.
8. Competitive vs noncompetitive inhibitionA competitive inhibitor binds the active site and can be overcome by more substrate. A noncompetitive inhibitor binds elsewhere and changes enzyme shape, lowering activity.
9. Overall equation for cellular respirationC6H12O6 + 6 O2 -> 6 CO2 + 6 H2O + energy (ATP and heat).
10. Stages of aerobic respiration and where they occurGlycolysis (cytoplasm), pyruvate oxidation and the citric acid cycle (mitochondrial matrix), oxidative phosphorylation (inner mitochondrial membrane).
11. Which stage of respiration makes the most ATP and how?Oxidative phosphorylation: the electron transport chain pumps H+ to build a gradient, and ATP synthase uses the H+ flow to make ATP (chemiosmosis). Oxygen is the final electron acceptor.
12. Light reactions vs Calvin cycle in photosynthesisLight reactions (thylakoid membranes) split water, release O2 and make ATP and NADPH. The Calvin cycle (stroma) uses ATP and NADPH to fix CO2 into sugar.
13. Mitosis vs meiosisMitosis yields 2 genetically identical diploid cells for growth and repair. Meiosis yields 4 genetically different haploid gametes through two divisions.
14. Name two sources of genetic variation generated in meiosis.Crossing over between homologous chromosomes in prophase I, and independent assortment of homologous pairs in metaphase I. Random fertilization adds more.
15. Genotype vs phenotypeGenotype is an organism's genetic makeup (e.g. Aa); phenotype is its observable traits, produced by genotype and environment.
16. Cross Aa x Aa. What are the expected genotype and phenotype ratios?Genotypes 1 AA : 2 Aa : 1 aa. With complete dominance, phenotypes are 3 dominant : 1 recessive.
17. What is a test cross?Crossing an individual with the dominant phenotype to a homozygous recessive. If any offspring show the recessive trait, the unknown parent is heterozygous.
18. Incomplete dominance vs codominanceIncomplete dominance: heterozygote is intermediate (red x white gives pink). Codominance: both alleles fully expressed (AB blood type).
19. Why are X-linked recessive disorders more common in males?Males have one X chromosome, so a single recessive allele on it is expressed; females need two copies. Examples: hemophilia, red-green color blindness.
20. State the central dogma of molecular biology.DNA is transcribed into mRNA, which is translated into protein. Transcription is in the nucleus in eukaryotes; translation is at ribosomes.
21. Base pairing rules in DNA and RNADNA: A with T, G with C. RNA has uracil in place of thymine, so A pairs with U.
22. What is natural selection?Individuals with heritable traits that improve survival and reproduction in an environment leave more offspring, so those traits become more common over generations.
23. Can an individual organism evolve? Explain.No. Populations evolve: evolution is a change in allele frequencies in a population over generations. Individuals do not change their genes in response to need.
24. Name four mechanisms that change allele frequencies.Natural selection, genetic drift (chance, strongest in small populations), gene flow (migration), and mutation. Nonrandom mating changes genotype frequencies.
25. Founder effect vs bottleneck effectBoth are genetic drift. Founder: a few individuals start a new population. Bottleneck: a population is drastically reduced by a disaster. Either can cut genetic diversity.
26. Homologous vs analogous structuresHomologous structures share ancestry though function may differ (human arm, bat wing). Analogous structures share function by convergent evolution, not ancestry (bird and insect wings).
27. What is the biological species concept?A species is a group of populations that can interbreed in nature and produce fertile offspring, and is reproductively isolated from other groups.
28. Allopatric vs sympatric speciationAllopatric: populations split by a geographic barrier diverge. Sympatric: new species arise in the same area, e.g. via polyploidy in plants or habitat differences.
29. What are the three domains of life?Bacteria, Archaea and Eukarya. Archaea are prokaryotes but share some molecular features with eukaryotes.
30. What does a phylogenetic tree show?Hypothesized evolutionary relationships; branch points (nodes) represent common ancestors, and sister taxa share the most recent common ancestor.