McMaster Bio 1M03: Exam 2025/2026
Exam Questions and Answers | 100%
Solved
Why might Pasteur's experiment be inconclusive? - 🧠 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? - 🧠 ANSWER ✔✔To ensure that
results were not achieved by random chance
What is the definition of a replicate? - 🧠 ANSWER ✔✔Unit that shares a common
thing (4 mice in one cage = 1 replicate)
What does the law of succession suggest? - 🧠 ANSWER ✔✔As one species
disappears, a similar one appears. Suggests ancestors and descendants
,What is the difference between vestigial traits and transitional features? - 🧠
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 - 🧠 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 - 🧠 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 - 🧠 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? - 🧠 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? - 🧠
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? - 🧠 ANSWER
✔✔Lamarckian evolution says evolution is goal directed. Bidirectional evolution
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, (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 - 🧠 ANSWER ✔✔-
Parasites lose complex digestive systems
- Finch beaks get larger, then smaller
Why can humans not fly? What constraints are in place? - 🧠 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? - 🧠
ANSWER ✔✔X is dominant, Y is recessive. Incompletely dominant.
What is evolution driven by? Of the four, which one introduces new alleles? - 🧠
ANSWER ✔✔Natural selection, gene flow, genetic drift, mutation. Mutation is the
only one that introduces new alleles into populations (other than gene flow)
Exam Questions and Answers | 100%
Solved
Why might Pasteur's experiment be inconclusive? - 🧠 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? - 🧠 ANSWER ✔✔To ensure that
results were not achieved by random chance
What is the definition of a replicate? - 🧠 ANSWER ✔✔Unit that shares a common
thing (4 mice in one cage = 1 replicate)
What does the law of succession suggest? - 🧠 ANSWER ✔✔As one species
disappears, a similar one appears. Suggests ancestors and descendants
,What is the difference between vestigial traits and transitional features? - 🧠
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 - 🧠 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 - 🧠 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 - 🧠 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? - 🧠 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? - 🧠
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? - 🧠 ANSWER
✔✔Lamarckian evolution says evolution is goal directed. Bidirectional evolution
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
PRIVACY STATEMENT. ALL RIGHTS RESERVED
, (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 - 🧠 ANSWER ✔✔-
Parasites lose complex digestive systems
- Finch beaks get larger, then smaller
Why can humans not fly? What constraints are in place? - 🧠 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? - 🧠
ANSWER ✔✔X is dominant, Y is recessive. Incompletely dominant.
What is evolution driven by? Of the four, which one introduces new alleles? - 🧠
ANSWER ✔✔Natural selection, gene flow, genetic drift, mutation. Mutation is the
only one that introduces new alleles into populations (other than gene flow)
