biology : class12 Selection for Intermediate Phenotypes : Directional Selection, Stabilising Selection, Disruptive Selection : Types of Natural Selection MCQ Questions and Answers
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Selection for Intermediate Phenotypes
MCQ questions and answers.
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MCQ Questions
1. Which type of natural selection favors individuals with intermediate phenotypes?
A.
Directional selection
B.
Stabilising selection
C.
Disruptive selection
D.
Artificial selection
Correct Answer:
Stabilising selection
Explanation:
Stabilising selection favors intermediate phenotypes and selects against extreme phenotypes.
2. In stabilising selection, which individuals are most likely to survive and reproduce?
A.
Individuals with only one extreme trait
B.
Individuals with intermediate traits
C.
Individuals with both extreme traits
D.
Individuals with newly developed traits
Correct Answer:
Individuals with intermediate traits
Explanation:
Stabilising selection gives an advantage to individuals showing the intermediate form of a trait.
3. What happens to extreme phenotypes during selection for intermediate phenotypes?
A.
They are usually favored
B.
They are usually selected against
C.
They always become dominant
D.
They become intermediate immediately
Correct Answer:
They are usually selected against
Explanation:
When intermediate phenotypes are favored, individuals at both extremes generally have lower survival or reproductive success.
4. Which example best represents selection for an intermediate phenotype?
A.
Very small and very large seeds are favored
B.
Only the largest seeds are favored
C.
Seeds of medium size are favored over very small and very large seeds
D.
All seed sizes have exactly the same advantage
Correct Answer:
Seeds of medium size are favored over very small and very large seeds
Explanation:
The medium-sized seed is an intermediate phenotype, and its advantage over both extremes illustrates stabilising selection.
5. How does selection for intermediate phenotypes generally affect variation in a population?
A.
It tends to reduce variation
B.
It always increases variation
C.
It removes all intermediate traits
D.
It changes every phenotype into an extreme
Correct Answer:
It tends to reduce variation
Explanation:
By selecting against extreme phenotypes, stabilising selection usually reduces variation around the intermediate form.
6. A population of animals has individuals with low, medium, and high body weight. If medium-weight animals survive best, which phenotype is being selected for?
A.
Low body weight
B.
High body weight
C.
Medium body weight
D.
Both low and high body weight
Correct Answer:
Medium body weight
Explanation:
Medium body weight is the intermediate phenotype, so it is favored in this example of stabilising selection.
7. What is the main effect of favoring intermediate phenotypes over generations?
A.
The population becomes centered around the intermediate trait
B.
The population shifts completely toward one extreme
C.
The population separates into two extreme groups
D.
The population loses all individuals with intermediate traits
Correct Answer:
The population becomes centered around the intermediate trait
Explanation:
Selection for intermediate phenotypes increases the relative frequency of individuals near the average form of the trait.
8. Which statement about stabilising selection is correct?
A.
It favors both extreme phenotypes
B.
It favors one extreme phenotype
C.
It favors the intermediate phenotype
D.
It gives an advantage only to new mutations
Correct Answer:
It favors the intermediate phenotype
Explanation:
The defining feature of stabilising selection is the preferential survival and reproduction of intermediate individuals.
9. If babies of average birth weight survive more often than very small or very large babies, what type of selection is occurring?
A.
Stabilising selection
B.
Directional selection
C.
Disruptive selection
D.
Sexual selection
Correct Answer:
Stabilising selection
Explanation:
Average birth weight is an intermediate phenotype, and its greater survival indicates selection for the intermediate form.
10. Under selection for intermediate phenotypes, which group usually has the highest fitness?
A.
Individuals with the average form of the trait
B.
Individuals with the lowest form of the trait
C.
Individuals with the highest form of the trait
D.
Individuals with traits outside the population range
Correct Answer:
Individuals with the average form of the trait
Explanation:
Intermediate or average individuals usually have the greatest fitness when stabilising selection is acting.
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