McMaster Bio 1M03: Exam 2023 Questions with all the correct answers;(Real actual exam)

Why might Pasteur's experiment be inconclusive? - ANS - The swan-necked flask broth may not support cell growth, or the broth was poisoned. Experiment did not confirm hypothesis that all cells come from pre-existing cells Why are replicates important in experiments? - ANS - To ensure that results were not achieved by random chance What is the definition of a replicate? - ANS - Unit that shares a common thing (4 mice in one cage = 1 replicate) What does the law of succession suggest? - ANS - As one species disappears, a similar one appears. Suggests ancestors and descendants What is the difference between vestigial traits and transitional features? - ANS - vestigial - useless features similar to useful features in related species (eg, coccyx in humans, tail in monkeys) transitional - intermediate feature seen in fossil species, between ancestral and descended species (eg, aquatic animal fins, tetrapod limbs) List potential outcomes of the bottleneck effect - ANS - - Potential high frequency of deleterious alleles that were previously at low frequency in source population - Different allele frequencies from source population, could lead to speciation - Strong genetic drift due to small population size Explain how the tuberculosis bacteria underwent natural selection during and after drug therapy - ANS - Variation: different strains → some resistant to drugs, some died Heritability: drug-resistant bacteria passed drug-resistant gene to daughter cells Differential fitness: bacteria that survived produced offspring Selection: drug-resistant allele had higher chance of survival through drug therapy Give three types of homologies. Provide an example for each - ANS - Genetic: similarity in RNA, DNA, amino acids (eg, AUG start codon shared with many living organisms) Developmental: similarities in embryonic form or developmental processes (eg, embryos of human, chicken, cat) Structural: similarity in adult features (eg, neck bone structure shared between giraffes and humans) What is the difference between acclimatization and adaptation? - ANS - Acclimatization: organism's response to the environment Adaptation: heritable trait that increases the fitness of an individual. Acclimatization does not change alleles, therefore it is not heritable. How are the Galapagos finches an example of directly observed evolution? - ANS - Beak morphology and body size is heritable, and changes due to the environment. Since evolution = ∆ in allele frequencies, selection for deeper beaks kills medium beaks. ∆ in food source selects for smaller beaks, which changes allele frequencies again.