Biology Practice Test 2: Evolution and Natural Selection
- Evolution and Natural Selection
- 10 questions
- 13 minutes
This second evolution test covers more mechanisms of evolution and ways new species form. Tip: natural selection only acts on variation that already exists; new alleles come from mutation.
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Question 1
Over thousands of years, people produced many dog breeds from ancestral wolves by choosing which dogs were allowed to breed. What is this process called?
Correct answer: A
When humans decide which individuals reproduce, it is artificial selection. Darwin used it as a model for natural selection, where the environment does the choosing.
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Question 2
Which explanation of long necks in giraffes fits the theory of natural selection?
Correct answer: B
Natural selection works on inherited variation that already exists. Traits gained by stretching during a lifetime are not inherited, and mutations do not appear because an animal needs them.
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Question 3
Early embryos of fish, chickens and humans all have a tail and pharyngeal pouches in the neck region. What does this similarity best support?
Correct answer: B
Similar early development is evidence of shared ancestry. It does not mean that one living species evolved from another living species.
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Question 4
Wind carries pollen from one population of a wildflower to another population of the same species several miles away. What is the most likely long-term effect?
Correct answer: C
Moving alleles between populations is gene flow. It mixes their gene pools, so the populations become more similar and are less likely to split into separate species.
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Question 5
Northern elephant seals were hunted until only a very small number survived. The population has since grown large again, but it has very little genetic variation. Which process explains the low variation?
Correct answer: A
A bottleneck is a sharp drop in population size that leaves only a few individuals, and many alleles are lost by chance. The founder effect also reduces variation, but it happens when a few individuals start a new population in a new place.
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Question 6
In a bird population, birds with small beaks eat small seeds well and birds with large beaks crack large seeds well. Birds with medium beaks handle neither seed well. Over time, small and large beaks become more common. Which type of selection is this?
Correct answer: C
Disruptive selection favors both extremes over the middle. Stabilizing selection would do the opposite and favor the medium beaks.
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Question 7
A hummingbird species has a long, curved beak that fits the long, curved flowers of a plant it feeds on, and the plant depends on this bird for pollination. Each has adapted to the other over many generations. What is this called?
Correct answer: B
In coevolution, two species that interact closely change in response to each other. Convergent evolution refers to unrelated species that develop similar traits independently.
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Question 8
A single species of finch-like bird reached the Hawaiian Islands long ago. Its descendants evolved into many species of honeycreepers with very different beaks for nectar, seeds and insects. What is this pattern called?
Correct answer: D
Adaptive radiation is the rapid evolution of many species from one ancestor, each adapted to a different way of life. Islands with empty niches often show this pattern.
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Question 9
What is the original source of new alleles in a population?
Correct answer: D
Only mutation creates brand-new alleles. Crossing over reshuffles alleles that already exist, and selection and drift change how common existing alleles are.
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Question 10
Two frog species live in the same pond. One breeds in early spring and the other in early summer, so they never mate with each other. Which type of reproductive isolation is this?
Correct answer: A
Temporal isolation means species breed at different times. The frogs share the same pond, so geographic isolation is not the barrier here.
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