McMaster Bio 1M03 UPDATED ACTUAL Exam Questions and CORRECT Answers
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McMaster Bio 1M03
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McMaster Bio 1M03
McMaster Bio 1M03 UPDATED ACTUAL
Exam Questions and CORRECT Answers
Why might Pasteur's experiment be inconclusive? - CORRECT ANSWER- The swannecked flask broth may not support cell growth, or the broth was poisoned. Experiment did
not confirm hypothesis that all cells come from pre-existing ...
McMaster Bio 1M03 UPDATED ACTUAL
Exam Questions and CORRECT Answers
Why might Pasteur's experiment be inconclusive? - CORRECT ANSWER- ✔✔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? - CORRECT ANSWER- ✔✔To ensure that
results were not achieved by random chance
What is the definition of a replicate? - CORRECT ANSWER- ✔✔Unit that shares a common
thing (4 mice in one cage = 1 replicate)
What does the law of succession suggest? - CORRECT ANSWER- ✔✔As one species
disappears, a similar one appears. Suggests ancestors and descendants
What is the difference between vestigial traits and transitional features? - CORRECT
ANSWER- ✔✔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 - CORRECT ANSWER- ✔✔- 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 - CORRECT ANSWER- ✔✔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 - CORRECT ANSWER-
✔✔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? - CORRECT ANSWER-
✔✔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? - CORRECT
ANSWER- ✔✔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.
How does the Galapagos finches exhibit non-Lamarckian evolution? - CORRECT
ANSWER- ✔✔Lamarckian evolution says evolution is goal directed. Bidirectional evolution
(deeper to smaller) goes against this; if it was goal, it would've gone in a single direction.
`Provide examples where evolution is not goal-directed - CORRECT ANSWER- ✔✔-
Parasites lose complex digestive systems
- Finch beaks get larger, then smaller
Why can humans not fly? What constraints are in place? - CORRECT ANSWER- ✔✔-
Historical constraints: since all traits come from previous traits, if we don't have a prior trait
for flying, we won't develop flight
- Genetic: we lack the necessary genes that would give us wings, flight, etc.
Individuals with genotype XX have same phenotype as genotype XY. Which allele is
dominant, and what are individuals with intermediate phenotypes called? - CORRECT
ANSWER- ✔✔X is dominant, Y is recessive. Incompletely dominant.
, What is evolution driven by? Of the four, which one introduces new alleles? - CORRECT
ANSWER- ✔✔Natural selection, gene flow, genetic drift, mutation. Mutation is the only one
that introduces new alleles into populations (other than gene flow)
For a given population, there is more observed heterozygotes than predicted in HWE. What
are some reasons this might occur? - CORRECT ANSWER- ✔✔- Non-random mating →
subconsciously prefer heterozygotes
- Natural selection → heterozygotes have an advantage over homozygotes (higher fitness)
In order for HWE to proceed, what assumptions must be made? - CORRECT ANSWER-
✔✔- random mating → gametes combine randomly
- no natural selection → parent generation survives and donates gametes
- no genetic drift → population is infinitely large **why does genetic drift affect small
populations?
- no gene flow → no alleles lost by migration
- no mutation → no new alleles
Why is low genetic variation bad? - CORRECT ANSWER- ✔✔If pathogen comes and
affects those certain alleles, it can eradicate entire population since no individuals will be able
to survive and reproduce.
How might a population come under directional selection? - CORRECT ANSWER- ✔✔-
Facing selection to develop characteristics that reinforce sexual isolation
- Develop traits that provide edge over competing species for resources
Obese babies can have trouble breathing, while tiny babies are prone to pneumonia and other
complicating affectations. What type of selection are babies likely under? - CORRECT
ANSWER- ✔✔Stabilizing selection → selection for intermediate phenotype, elimination of
extremes
How can inbreeding lead to accelerated natural selection? - CORRECT ANSWER-
✔✔Inbreeding often results in deleterious recessive alleles. Recessive alleles are under
purifying selection
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