1. Which type of natural selection favors one extreme phenotype in a population?
A.
Directional selection
B.
Stabilising selection
C.
Disruptive selection
D.
Random selection
Correct Answer:
Directional selection
Explanation:
Directional selection favors one extreme phenotype, causing the population's characteristics to shift toward that extreme.
2. In directional selection, which individuals are more likely to survive and reproduce?
A.
Individuals with an average phenotype
B.
Individuals with one extreme phenotype
C.
Individuals with both extreme phenotypes equally
D.
Individuals with no variation
Correct Answer:
Individuals with one extreme phenotype
Explanation:
Directional selection gives an advantage to individuals at one extreme of a phenotypic range.
3. Which type of selection favors both extreme phenotypes over the intermediate phenotype?
A.
Directional selection
B.
Stabilising selection
C.
Disruptive selection
D.
Artificial selection
Correct Answer:
Disruptive selection
Explanation:
Disruptive selection favors individuals at both extremes and selects against individuals with intermediate characteristics.
4. What happens to the intermediate phenotype during disruptive selection?
A.
It is always favored
B.
It is selected against
C.
It becomes the only phenotype
D.
It changes into one extreme immediately
Correct Answer:
It is selected against
Explanation:
Disruptive selection favors both extreme phenotypes, making the intermediate phenotype less successful.
5. Which type of selection favors the average phenotype and acts against both extreme phenotypes?
A.
Directional selection
B.
Disruptive selection
C.
Stabilising selection
D.
Sexual selection
Correct Answer:
Stabilising selection
Explanation:
Stabilising selection favors intermediate individuals and reduces the survival or reproduction of both extremes.
6. A population of birds begins to have mostly larger beaks because birds with larger beaks obtain food more successfully. Which selection is shown?
A.
Directional selection
B.
Stabilising selection
C.
Disruptive selection
D.
No natural selection
Correct Answer:
Directional selection
Explanation:
The larger beak is one extreme phenotype, and selection shifts the population toward that extreme.
7. If both very small and very large individuals survive better than medium-sized individuals, which selection is occurring?
A.
Directional selection
B.
Stabilising selection
C.
Disruptive selection
D.
Artificial selection
Correct Answer:
Disruptive selection
Explanation:
Disruptive selection increases the success of both extreme phenotypes while reducing the success of the intermediate phenotype.
8. Which selection pattern reduces the number of individuals with extreme phenotypes?
A.
Stabilising selection
B.
Directional selection
C.
Disruptive selection
D.
Directional change
Correct Answer:
Stabilising selection
Explanation:
Stabilising selection favors the intermediate phenotype and selects against both extreme phenotypes.
9. A population becomes more similar to one extreme form over many generations. Which type of selection most likely caused this change?
A.
Stabilising selection
B.
Disruptive selection
C.
Directional selection
D.
Balanced selection
Correct Answer:
Directional selection
Explanation:
A gradual shift toward one extreme phenotype is the characteristic result of directional selection.
10. Which statement correctly describes selection for extreme phenotypes?
A.
It always favors only average individuals
B.
It may favor one or both extreme forms
C.
It removes all phenotypic variation immediately
D.
It prevents organisms from reproducing
Correct Answer:
It may favor one or both extreme forms
Explanation:
Directional selection favors one extreme, while disruptive selection favors both extremes.
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