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Revision Examination Tests
“Come all for this Greatness”
... 100% Correct Ans ...
McMaster Bio 1M03: Exam
TEST 2024-2025 ACTUAL EXAM COMPLETE 200-
QUESTIONS AND CORRECT DETAILED ANSWERS
Quiz 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
Quiz Why are replicates important in experiments?
Ans: To ensure that results were not achieved by random chance
Quiz What is the definition of a replicate?
Ans: Unit that shares a common thing (4 mice in one cage = 1 replicate)
Quiz What does the law of succession suggest?
Ans: As one species disappears, a similar one appears. Suggests ancestors and
descendants
Quiz 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)
Quiz 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
,Quiz 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
Quiz 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)
Quiz 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.
Quiz 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.
Quiz How does the Galapagos finches exhibit non-Lamarckian evolution?
Ans: 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.
Quiz `Provide examples where evolution is not goal-directed
Ans: - Parasites lose complex digestive systems
- Finch beaks get larger, then smaller
Quiz Why can humans not fly? What constraints are in place?
Ans: - 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.
Quiz Individuals with genotype XX have same phenotype as genotype XY. Which
allele is dominant, and what are individuals with intermediate phenotypes called?
, Ans: X is dominant, Y is recessive. Incompletely dominant.
Quiz What is evolution driven by? Of the four, which one introduces new alleles?
Ans: Natural selection, gene flow, genetic drift, mutation. Mutation is the only one
that introduces new alleles into populations (other than gene flow)
Quiz For a given population, there is more observed heterozygotes than predicted in
HWE. What are some reasons this might occur?
Ans: - Non-random mating → subconsciously prefer heterozygotes
- Natural selection → heterozygotes have an advantage over homozygotes (higher
fitness)
Quiz In order for HWE to proceed, what assumptions must be made?
Ans: - 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
Quiz Why is low genetic variation bad?
Ans: If pathogen comes and affects those certain alleles, it can eradicate entire
population since no individuals will be able to survive and reproduce.
Quiz How might a population come under directional selection?
Ans: - Facing selection to develop characteristics that reinforce sexual isolation
- Develop traits that provide edge over competing species for resources
Quiz 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?
Ans: Stabilizing selection → selection for intermediate phenotype, elimination of
extremes
Quiz How can inbreeding lead to accelerated natural selection?
Ans: Inbreeding often results in deleterious recessive alleles. Recessive alleles are
under purifying selection
Quiz What can cause a species living in sympatry to diverge? What must it
overcome?
Ans: Disruptive selection, gene flow
Revision Examination Tests
“Come all for this Greatness”
... 100% Correct Ans ...
McMaster Bio 1M03: Exam
TEST 2024-2025 ACTUAL EXAM COMPLETE 200-
QUESTIONS AND CORRECT DETAILED ANSWERS
Quiz 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
Quiz Why are replicates important in experiments?
Ans: To ensure that results were not achieved by random chance
Quiz What is the definition of a replicate?
Ans: Unit that shares a common thing (4 mice in one cage = 1 replicate)
Quiz What does the law of succession suggest?
Ans: As one species disappears, a similar one appears. Suggests ancestors and
descendants
Quiz 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)
Quiz 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
,Quiz 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
Quiz 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)
Quiz 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.
Quiz 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.
Quiz How does the Galapagos finches exhibit non-Lamarckian evolution?
Ans: 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.
Quiz `Provide examples where evolution is not goal-directed
Ans: - Parasites lose complex digestive systems
- Finch beaks get larger, then smaller
Quiz Why can humans not fly? What constraints are in place?
Ans: - 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.
Quiz Individuals with genotype XX have same phenotype as genotype XY. Which
allele is dominant, and what are individuals with intermediate phenotypes called?
, Ans: X is dominant, Y is recessive. Incompletely dominant.
Quiz What is evolution driven by? Of the four, which one introduces new alleles?
Ans: Natural selection, gene flow, genetic drift, mutation. Mutation is the only one
that introduces new alleles into populations (other than gene flow)
Quiz For a given population, there is more observed heterozygotes than predicted in
HWE. What are some reasons this might occur?
Ans: - Non-random mating → subconsciously prefer heterozygotes
- Natural selection → heterozygotes have an advantage over homozygotes (higher
fitness)
Quiz In order for HWE to proceed, what assumptions must be made?
Ans: - 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
Quiz Why is low genetic variation bad?
Ans: If pathogen comes and affects those certain alleles, it can eradicate entire
population since no individuals will be able to survive and reproduce.
Quiz How might a population come under directional selection?
Ans: - Facing selection to develop characteristics that reinforce sexual isolation
- Develop traits that provide edge over competing species for resources
Quiz 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?
Ans: Stabilizing selection → selection for intermediate phenotype, elimination of
extremes
Quiz How can inbreeding lead to accelerated natural selection?
Ans: Inbreeding often results in deleterious recessive alleles. Recessive alleles are
under purifying selection
Quiz What can cause a species living in sympatry to diverge? What must it
overcome?
Ans: Disruptive selection, gene flow
