biology : class12 Human Birth Weight : Directional Selection, Stabilising Selection, Disruptive Selection : Types of Natural Selection MCQ Questions and Answers
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Human Birth Weight
MCQ questions and answers.
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MCQ Questions
1. Which type of natural selection is commonly illustrated by human birth weight?
A.
Stabilising selection
B.
Directional selection
C.
Disruptive selection
D.
Artificial selection
Correct Answer:
Stabilising selection
Explanation:
In human birth weight, babies with an intermediate weight generally have a better chance of survival than babies with very low or very high birth weights.
2. In human birth weight, which babies are generally favoured by stabilising selection?
A.
Babies with extremely low birth weight
B.
Babies with extremely high birth weight
C.
Babies with an intermediate birth weight
D.
Babies with any birth weight equally
Correct Answer:
Babies with an intermediate birth weight
Explanation:
Stabilising selection favours the average or intermediate birth weight and selects against both extremes.
3. What happens to babies with very low birth weight compared with babies of intermediate birth weight?
A.
They usually have a higher survival rate
B.
They may have a lower survival rate
C.
They are always healthier
D.
They are unaffected by natural selection
Correct Answer:
They may have a lower survival rate
Explanation:
Very low birth weight can be associated with health problems, so such babies may have a lower survival rate than babies with intermediate birth weight.
4. Why are babies with very high birth weight often selected against?
A.
They may face difficulties during birth
B.
They cannot receive nutrients before birth
C.
They always have weak bones
D.
They are unable to grow after birth
Correct Answer:
They may face difficulties during birth
Explanation:
Very high birth weight can make delivery more difficult, which can reduce survival and reproductive success.
5. Which pattern best describes natural selection acting on human birth weight?
A.
Both very low and very high birth weights are favoured
B.
Only very low birth weight is favoured
C.
Intermediate birth weight is favoured over both extremes
D.
Birth weight has no effect on survival
Correct Answer:
Intermediate birth weight is favoured over both extremes
Explanation:
This pattern is the defining feature of stabilising selection in human birth weight.
6. If babies at both extremes of birth weight have lower survival, what happens to the variation in birth weight over generations?
A.
It tends to decrease
B.
It always doubles
C.
It changes only toward very low weight
D.
It changes only toward very high weight
Correct Answer:
It tends to decrease
Explanation:
Stabilising selection removes or reduces the success of extreme birth weights, tending to reduce variation around the average.
7. A population has many babies with an average birth weight and fewer babies with extreme birth weights. Which selection pattern does this suggest?
A.
Stabilising selection
B.
Disruptive selection
C.
Directional selection
D.
No selection
Correct Answer:
Stabilising selection
Explanation:
A concentration around an intermediate birth weight is expected when stabilising selection favours average-sized babies.
8. Which birth-weight group is most likely to have the greatest survival advantage in a population affected by stabilising selection?
A.
The smallest babies
B.
The largest babies
C.
Babies near the average weight
D.
Babies with no measurable weight
Correct Answer:
Babies near the average weight
Explanation:
Babies near the average birth weight are favoured because both very low and very high birth weights can present risks.
9. What would be the likely result if natural selection favoured only heavier babies in a human population?
A.
Birth weight would tend to shift toward higher values
B.
Birth weight would remain exactly unchanged
C.
Both low and high birth weights would be equally favoured
D.
Intermediate birth weight would always be favoured
Correct Answer:
Birth weight would tend to shift toward higher values
Explanation:
Selection favouring one end of the birth-weight range would be directional selection, causing the population average to move toward higher birth weights.
10. Which statement about human birth weight and natural selection is correct?
A.
Very low birth weight is always the most successful
B.
Very high birth weight is always the most successful
C.
Intermediate birth weight often provides the best survival advantage
D.
Birth weight has no relationship with survival
Correct Answer:
Intermediate birth weight often provides the best survival advantage
Explanation:
Human birth weight commonly shows stabilising selection because intermediate-weight babies often survive better than babies at either extreme.
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