BIOCHEM 32A Exam 2 MC 50 Questions and Answers Updated 2024/2025 Solved 100%; University of Notre Dame

BIOCHEM 32A Exam 2 MC 50 Questions and Answers Updated 2024/2025 Solved 100%; University of Notre Dame 1. Georges Cuvier proposed , which directly opposed the idea that Earth’s geological features can be explained by constant, steady mechanisms. A. Gradualism B. Catastrophism C. Uniformitarianism D. Adaptationism Consider the following statement for Questions 2 through 4: In Mendelian genetics, complete dominance is a heterozygous condition where the dominant allele masks any effect of the recessive allele. You have sampled a population of 500 glass-wing butterflies to look for resistance to a novel butterfly pathogen. In your sample population, you have found 16% of the butterflies are resistant due to a recessive gene. All other butterflies are affected, indicating that susceptibility to the disease exhibits complete dominance inheritance patterns. Use the space below for any calculations: 2. What is the frequency of the dominant allele? A. 0.40 B. 0.48 C. 0.60 D. 0.36 3. What is the percentage of the population that is homozygous dominant? A. 36.0% B. 48.0% C. 84.0% D. 60.0% 4. How many individuals within the population are susceptible to the pathogen? A. 300 B. 180 C. 240 D. 420 5. The method for generating evolutionary trees known as Maximum Likelihood can be defined as: A. A set of probability rules about how DNA changes over time and the assumption that a tree can be found that reflects the most likely sequence of evolutionary events B. An assumption that that the tree that requires the fewest evolutionary events is the most likely C. A set of probability rules about how organisms change over time at a phenotypic level D. An assumption that a tree can be built based on DNA information that relays environmental and behavioral selective pressures 6. An ancestral species of archaea was thought to have inhabited the near-shore region of one of the Yellowstone hot springs. Over time, this archaea reproduced asexually via binary fission and evolved into two unique organisms. Structurally identical, one lineage is more adapted to the deeper waters near the center of the spring, while the other has adapted to the soil conditions just outside the water. Which species concept would be most useful for differentiating the two organisms? A. The biological species concept B. The ecological species concept C. The morphological species concept D. The chronological species concept 7. A species of finch with a short, thick beak that primarily feasts on nuts is introduced to an island whose only food source is insects. In a few years, scientists note that the finches’ with shorter beaks have lower survival rates and produce fewer offspring than those that have developed longer, more slender beaks. We can consider this an example of: A. Adaptive radiation B. Natural selection C. The founder effect D. Genetic drift 8. The process by which the reproductive barriers between two parent species of a hybrid population strengthen, resulting in fewer and fewer hybrids being produced is: A. Hybrid fusion B. Hybrid reinforcement C. Hybrid breakdown D. Hybrid stability 9. Which of the following is not an example of an exaptation? A. Birds utilizing the feathers that helped keep them thermoregulated for use in flight. B. Bacteria adapting the syringe-like Type III secretion system into the flagella for movement. C. Humans evolving an extra curve of the spine to walk upright as opposed to primarily on all four limbs. D. Mammals repurposing of two of the three bones in the reptilian jaw to become the malleus and incus (hammer and anvil) bones of the middle ear. Consider the following figure for Questions 10 through 13: 10. The clade containing the Lysinibacillus species and the common ancestors “A”, “B”, and “C” would be considered a group. A. Monophyletic B. Diphyletic C. Paraphyletic D. Polyphyletic 11. This tree was built using an algorithm that assumes that the tree that requires the fewest evolutionary events is the most likely. This method of building trees is called: A. Clustalω B. Maximum parsimony C. Paraphyletic arrangement D. Maximum likelihood 12. The group included within the rectangle would be considered a group. A. Monophyletic B. Diphyletic C. Paraphyletic D. Polyphyletic 13. Escherichia coli, the only Gram-negative species, would be considered a(n) if we were only interested in Gram-positive organisms. A. Root species. B. Common ancestor C. Outgroup D. All of the above E. None of the above 14. Individuals affected by cystic fibrosis (CF) often suffer from the buildup of mucus in the lungs resulting in difficulty breathing, among other symptoms. These individuals possess two copies of the recessive CF gene. Data suggests that carrying only one copy of the recessive gene may provide by aiding in the resistance to cholera, tuberculosis, and other similar diseases. A. Hybrid viability B. Relative fitness C. An exaptation D. Heterozygous advantage 15. is when organisms rapidly evolve to fill an ecological niche after an extinction event. A. Macroevolution B. Cambrian explosion C. Heterochrony D. Adaptive radiation 16. In a population of 500 organisms, 200 are homozygous dominant for a trait, 250 are heterozygous, and the remaining 50 are homozygous recessive. During one mating season, only 50 organisms mate, 48 of which are homozygous recessive. These matings produce 37 homozygous recessive individuals and 6 heterozygous individuals. following generation. could be used to describe the random chance that led to decreased variation in the A. Gene flow B. Homozygous advantage C. Genetic drift D. Incomplete dominance 17. 2,500 out of 4,000,000 cave-dwelling bats survive the flooding of their roosting cavern by a local farmer who feared that all bats carry rabies. After this incident, a local wildlife conservationist works with the community to spread awareness of bat safety and their benefit in controlling mosquito populations, and helps to re-build the decimated bat population. This would be an example of: A. The founder effect B. Genetic drift C. The bottleneck effect D. Hybrid reinforcement 18. Darwinian evolution can best be described as: A. The innate drive towards complexity B. A rapid appearance of species to fill an ecological niche C. A process by which one species splits into two or more species. D. The relationship of current species to ancestral species of the remote past 19. Which of the following was not observed or inferred by Darwin in regards to natural selection? A. The accumulation of favorable traits in a population is due to an unequal ability to survive by individuals within the population. B. Inherited traits vary between members of a population. C. Species only produce enough offspring to be supported by the environment, and some of these offspring fail to survive and reproduce. D. Advantageous traits provide individuals an increased chance of survival and reproduction. 20. Which of the following examples can best be described as a postzygotic barrier? A. Two hybrid tomato plants are crossed to produce a second generation hybrid. This second generation plant exhibits stunted growth and never produces any fruits. B. Two populations of strawberries are grown in the same field. One population is tetraploid (four copies of the chromosomes) and the other is heptaploid (seven copies). C. Two species of field mouse inhabit the same strawberry patch. One species is nocturnal, operating only at night, while the other is diurnal, operating only during the day. D. Two species of bushbabies (galagos) unable to mate due to differing structures of their reproductive organs. E. None of the above. 21. As human evolved, we retained more neotenous, or juvenile, traits as compared to some of our close evolutionary relatives (e.g. gorillas). This is an example of: A. Heterochrony B. Heterozygosity C. Polyploidy D. Parsimony 22. When organisms diverge from a common ancestor, the resulting species share a number of genes that perform the same function. However, if one of these species has a gene duplication event, the resulting genes are and can take on new functions over time. A. Paralogous : Orthologous B. Analogous : Orthologous C. Paralogous : Analogous D. Orthologous : Paralogous 23. The natural phenomenon where opposing biological sexes of a single species display vastly different phenotypes is called: A. Intersexual selection B. Heterochrony C. Intrasexual selection D. Sexual dimorphism 24. are the portions of the DNA that code for a protein or peptide sequence in eukaryotes. A. Introns B. Codons C. Exons D. Ultrons 25. A new, hypothetical drug (Mersagone) has been developed to target a specific DNA sequence in the Methicillin- Resistant Staphylococcus aureus (MRSA) pathogen’s DNA replication machinery. After three years of successfully treating MRSA, the pathogen has begun to show resistance to Mersagone. Which of the following is not a likely reason for this new resistance? Question thrown out. A. The DNA sequence has mutated to the point that the sequence is no longer recognized by Mersagone. B. Some Mersagone-resistant bacteria were present at the start of treatment and natural selection increased their frequency. C. Mersagone-resistant MRSA evolved a novel export pump that bears no homology to any other cellular machinery. D. MRSA strains have modified an existing Type VII secretion system to export Mersagone. 26. Gene duplication, sexual reproduction, and mutation are all sources of . A. Gene flow B. Genetic variation C. Horizontal gene transfer D. Phenotypic variation 27. The following picture depicts which class of structures? A. Analogous structures B. Homologous structures C. Vestigial structures D. Adaptive structures 28. In a population of 2,000 hares, coat color ranges from dark brown to snowy white. A small percentage of these animals are randomly removed from their native habitat and placed in the arctic where future generations see a higher frequency of lighter colored coats. This is an example of which of the following? A. Natural selection B. Adaptation C. The founder effect D. Directional selection E. All of the above 29. Which of the following is not a possible outcome of a single point mutation within a gene sequence? A. The gene exhibits a neutral mutation due to a change in the third position of a codon for Leucine that does not change the resulting amino acid. (Leucine has six possible combinations that code for it) B. A mutation in the gene’s start codon causes it to not be transcribed. C. A mutation in the first position of a codon causes early termination of the gene and results in a non- functioning protein. D. The gene exhibits a neutral mutation resulting from an amino acid change that does not affect the folding pattern or enzymatic activity of the protein. E. None of the above. 30. In an essential feline housekeeping gene, a point mutation that causes which change is most likely to give rise to a new allele? A. A small variation in protein folding at the enzyme’s active site. B. Termination of translation prior to the translation of the enzyme’s active site. C. A variation in the intron region of the gene. D. A change in the third position of a codon coding for Proline (CCA, CCC, CCG, or CCT). 31. Which of the following is true regarding the endosymbiotic theory? A. The endosymbiont transcribes and translates its own DNA B. The inner membrane of the mitochondria resembles that of current-day bacteria C. The ribosomes of chloroplasts are more similar to bacterial ribosomes than eukaryotic ribosomes D. An early prokaryotic cell engulphed a beneficial bacterial cell but did not digest it E. All of the above 32. In an inland pond, you are able to observe a single species of fish. One year, during a severe drought, the water level drops, resulting in several separate, well-isolated pools. After several dry seasons, you go back to find unique species inhabiting each pool. Which type of speciation would this be considered? A. Allopatric B. Sympatric C. Reinforced D. Ecological 33. A protocell is best described as: A. A single celled organism that lacks any internal organelles. B. A spherical polymer of montmorillonite clay that surrounds organic compounds. C. A spontaneously formed sphere of lipids with a membrane-like structure. D. A protein coat surrounding nucleic acid that may be encompassed by a membrane. 34. is the process by which humans have modified other species by selecting and breeding organisms with desired traits. A. Genetic engineering B. Natural selection C. Hybridization D. Artificial selection 35. Aristotle, Lamarck, and Darwin all developed ideas about how organisms came into being. Order these theories from oldest to newest. A. Darwinian Evolution : Lamarckian Evolution : Scala Naturae B. Lamarckian Evolution : Scala Naturae : Darwinian Evolution C. Scala Naturae : Darwinian Evolution : Lamarckian Evolution D. Scala Naturae : Lamarckian Evolution : Darwinian Evolution E. Lamarckian Evolution : Scala Naturae : Darwinian Evolution 36. Suppose we find evidence for an early protocell that has RNA as its genetic material. As it evolves, which of the following would be a good reason for evolving a DNA-based genome? A. DNA allows for faster mutations due to an accelerated replication process. B. The extra hydroxyl (-OH) group in DNA allows for it to be acted upon more readily. C. Double-stranded DNA is more chemically stable. D. The six-carbon ring of DNA is less chemically active than the five-carbon ring of RNA. 37. While out on an expedition in the Amazon rainforest, you discover what you believe to be a novel species of butterfly. While your lab doesn’t have the funding to sequence the entire butterfly’s genome, you are able sequence the mitochondrial DNA. Why might that prove useful to you? A. mtDNA can be used to examine recent evolutionary events due to its rapid evolution. B. Due to its relatively slow rate of change, mtDNA can be useful for investigating branch points from millions of years ago. C. It can tell us what species of mitochondrial precursor bacterium was associated with this species of butterfly. D. Being the powerhouse of the cell, the mitochondria can tell us what types of adaptations the butterfly may have accumulated. 38. Uniformitarianism is: A. The theory that Earth’s geological features can be explained via gradual mechanisms. B. The theory that Earth’s geological processes of the past are still operating today at the same rates. C. The theory that remains of organisms of the past can be found within Earth’s sedimentary rock layers. D. The theory that strata are separated by cataclysmic events in Earth’s history. 39. Phylogenetic trees are a useful tool in understanding patterns of descent among organisms. However they do have their limitations. What is something else that we can learn from these types of analyses? A. How long ago a species evolved. B. Important data regarding similar characteristics in related species. C. Visible, phenotypic similarities between organisms. D. The amount of change between organisms within the same clade. 40. During the Cambrian Explosion, we see the first evidence of: A. Multi-cellular life forms B. Life on land C. Predator-prey interactions D. A mass extinction 41. In nature, several types of organisms have evolved specialized structures that help them produce lift while moving through the air including birds, beetles, bats, and even some species of tree that use autorotational descent for their seeds. The formation of wings and wing-like structures in these various organisms would be considered . A. Divergent evolution B. Convergent evolution C. Structural homology D. Orthologous structures 42. Horizontal gene transfer can describe all but which of the following? A. The appearance of orthologous genes in closely related species. B. Disparities between gene trees. C. The transfer of genes between archaea, bacteria, and eukaryotes. D. The tangled network of branches among early organisms in the tree of life. 43. The molecular clock can best be described as: A. The estimation of evolutionary divergences to predict the uncertainty assigned to the fossil record B. A representation of the evolutionary history of life on Earth C. An estimation of the absolute time of evolutionary change using the constant rates of evolution in some genes D. A representation of genomic similarity of related species using multiple genes that evolved in different taxa. 44. As an organism evolves and extends its range, over time it will produce two or more species. This process is known as: A. Speciation B. Natural selection C. Adaptation D. Hybridization 45. We are arguably in the sixth great mass extinction, brought on by our own disregard for the environment. If at the end of this mass extinction event, 95% of all species have gone extinct, humanity included, what process would best describe the rapid diversification of life that would occur to fill the now vacant ecosystems? A. Habitat isolation B. Balancing selection C. Natural selection D. Adaptive radiation 46. In northwest North America, the geographic ranges of the Polar Bear and the Grizzly Bear overlap, and the two species can occasionally produce a hybrid Grolar Bear (also sometimes called a Pizzly Bear. And no, I’m not making this one up). If, over time, the two parent species have a breakdown of their zygotic barriers and ultimately form a single species, we would call this . A. Hybrid reinforcement B. Hybrid fusion C. Hybrid stability D. Hybrid breakdown 47. Which of the following was not theorized to be a possible early endosymbiont? A. Mitochondria B. Plastid C. Lysosome D. Chloroplast 48. Somewhere between 2.7 and 2.4 billion years ago, there was a massive shift in the Earth’s atmosphere. Organisms began producing via photosynthesis which led to the . A. Oxygen : Oxygen Revolution B. Oxygen : Cambrian Explosion C. Carbon Dioxide : Cambrian Explosion D. Carbon Dioxide : Oxygen Revolution 49. On a lost island in the pacific, there exists a bird who’s DNA encode large, powerful wings and average strength legs. Due to a fluke in the environment, however, this bird uses its legs extensively to run down its prey and almost never utilizes its wings. If Lamarckian evolution were true, we would expect the offspring to have which of the following traits? A. Large wings, powerful legs B. Small wings, average legs C. Small wings, powerful legs D. Large wings, average legs 50. In the 1800s, Gregor Mendel performed several experiments on locally grown pea plants. By analyzing the results, he was able to provide evidence for what he described as “discrete heritable units”. Today, we know them as . A. Chromosomes B. Proteins C. Genes D. Plasmids