WorksheetsBIO-1407 Practice Exam 1
Total questions: 25
Worksheet time: 13mins
Name
Class
Date
1.
Which statement best defines microevolution?
a)
Random mutations that never affect phenotype
b)
Developmental changes during an organism’s life
c)
Changes in climate that alter species ranges
d)
Heritable allele frequency shifts within a population across generations
e)
Appearance of new body plans over geologic eras
2.
Which process tends to make populations more genetically similar over time?
a)
Nonrandom mating
b)
Natural selection
c)
Genetic drift
d)
Mutation
e)
Gene flow
3.
In a large, randomly mating population at equilibrium for a gene with two alleles, the frequency of allele A is [p] = 0.6. What is the expected frequency of heterozygotes?
a)
0.60
b)
0.24
c)
0.36
d)
0.48
e)
0.16
4.
A population of finches experiences a prolonged drought that favors birds with deeper beaks; the trait distribution shifts to a higher mean with similar variance. Which selection mode best explains this change?
a)
Stabilizing selection
b)
Frequency‑dependent selection (negative)
c)
Disruptive selection
d)
Directional selection
e)
Balancing selection via heterozygote advantage
5.
Two insect populations occupy the same meadow, but one mates only at dawn and the other only at dusk. Which barrier most directly limits gene flow?
a)
Temporal isolation
b)
Habitat isolation
c)
Gametic isolation
d)
Mechanical isolation
e)
Reduced hybrid fertility
6.
Fossil data show long periods with little morphological change punctuated by brief intervals of rapid divergence among lineages. This pattern is best described as:
a)
Punctuated equilibrium
b)
Hardy–Weinberg equilibrium
c)
Gradualism
d)
Orthogenesis
e)
Saltationism within single generations
7.
Which mechanism most rapidly generates reproductive isolation in flowering plants?
a)
Founder effect
b)
Reinforcement after secondary contact
c)
Sexual selection on floral color
d)
Polyploidization following hybridization
e)
Directional selection across a cline
8.
Arrange the following early‑Earth events from earliest to latest:
1. Formation of protocell‑like compartments
2. Abiotic synthesis of organic monomers
3. Emergence of catalytic, self‑replicating RNA
4. Polymerization into macromolecules
a)
4, 2, 3, 1
b)
2, 1, 4, 3
c)
2, 4, 3, 1
d)
1, 2, 4, 3
e)
2, 4, 1, 3
9.
Which observation most strongly supports a bacterial origin of mitochondria?
a)
Location in the cytoplasm
b)
Abundance in muscle cells
c)
Presence of cristae
d)
Double membrane with inner membrane proteins resembling bacterial transporters
e)
Association with ATP synthase
10.
Layered, dome‑shaped rock structures interpreted as ancient microbial mats are called:
a)
Coprolites
b)
Stromatolites
c)
Varves
d)
Amber inclusions
e)
Concretions
11.
Which pair best illustrates homology?
a)
Shark fin and penguin wing
b)
Dolphin flipper and human arm
c)
Bat wing and insect wing
d)
Octopus tentacle and cat forelimb
e)
Bird wing and butterfly wing
12.
In the simplified tree (not shown) taxa C and D share a most recent common ancestor not shared with B. Which statement is correct?
a)
C and D are sister taxa
b)
C forms a paraphyletic group with D
c)
B, C, D form a monophyletic clade excluding their ancestor
d)
B and C are sister taxa
e)
D is the outgroup
13.
Which statement best characterizes genetic drift?
a)
Mutation bias that favors AT‑rich genomes
b)
Movement of alleles between populations via migrants
c)
Nonrandom mating that alters genotype frequencies only
d)
Random sampling effects, strongest in small populations
e)
Systematic increase in advantageous alleles due to fitness differences
14.
Which outcome is unique to natural selection among the major evolutionary forces?
a)
Increased genetic similarity between populations
b)
Consistent tendency to generate adaptation
c)
Shifts in genotype frequencies without allele change
d)
Production of new alleles
e)
Change in allele frequencies
15.
In a population at Hardy–Weinberg equilibrium, the recessive phenotype frequency is 0.09. Assuming complete recessivity and two alleles, what proportion of the population are carriers (heterozygotes)?
a)
0.09
b)
0.30
c)
0.70
d)
0.42
e)
0.18
16.
In a variable environment, birds with either very short or very long tails obtain more mates than birds with intermediate tail lengths. Over time, the trait distribution becomes bimodal. Which selection mode is indicated?
a)
Directional
b)
Disruptive
c)
Positive frequency‑dependent
d)
Stabilizing
e)
Balancing via heterozygote advantage
17.
Two closely related frog species have overlapping ranges but use different courtship calls; females respond only to the call of their own species. This is an example of:
a)
Mechanical isolation
b)
Behavioral isolation
c)
Hybrid inviability
d)
Gametic isolation
e)
Temporal isolation
18.
Hybrid offspring of two lizard species survive to adulthood but produce abnormal gametes and are sterile. This barrier is best described as:
a)
Behavioral isolation (prezygotic)
b)
Hybrid inviability (postzygotic)
c)
Reduced hybrid fertility (postzygotic)
d)
Habitat isolation (prezygotic)
e)
Mechanical isolation (prezygotic)
19.
Place these evolutionary milestones in the correct order from earliest to most recent:
1. Appearance of oxygenic photosynthesis
2. Origin of eukaryotic mitochondria
3. First multicellular eukaryotes
4. Colonization of land by plants
a)
3, 2, 1, 4
b)
1, 3, 2, 4
c)
1, 2, 4, 3
d)
2, 1, 3, 4
e)
1, 2, 3, 4
20.
Which set could form a monophyletic group on a properly rooted tree?
a)
A grade including an ancestor and some descendants
b)
All living taxa plus the outgroup
c)
All taxa that share similar habitats
d)
A common ancestor and all of its descendants
e)
Any two taxa that look alike
21.
An aquatic microbe uses light as an energy source and CO₂ as its carbon source. Its nutritional mode is best described as:
a)
Photoautotroph
b)
Lithoheterotroph
c)
Photoheterotroph
d)
Chemoautotroph
e)
Chemoheterotroph
22.
A bacterium normally living on leaf surfaces without affecting the plant begins causing leaf spots under drought stress, then colonizes fallen leaves after senescence. Across this sequence, its roles are best described as:
a)
Commensal, mutualist, producer
b)
Producer, decomposer, pathogen
c)
Pathogen, commensal, producer
d)
Mutualist, pathogen, producer
e)
Commensal, pathogen, decomposer
23.
Two beetle populations separated by a mountain range diverge genetically for many generations. Upon secondary contact, hybrids have low survival. Which sequence best matches the processes leading to full speciation?
a)
Gene flow, hybrid vigor, fusion
b)
Sympatric divergence, reinforcement, gene flow increase
c)
Allopatric divergence, reinforcement, reduced hybridization
d)
Drift only, immediate reproductive isolation
e)
Polyploidy, instantaneous isolation, sympatry
24.
In phylogenetic analysis, the outgroup is used primarily to:
a)
Identify paraphyletic groups directly
b)
Test for convergent evolution only
c)
Root the tree and polarize character states
d)
Increase the number of taxa in the ingroup
e)
Estimate absolute divergence times
25.
Which statement best defines gene flow?
a)
Changes in allele frequencies due to random sampling
b)
The tendency of heterozygotes to have the highest fitness
c)
Movement of alleles between populations via migration and reproduction
d)
Spontaneous formation of new genes during development
e)
Differential reproductive success among genotypes
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