MCQ practice · SSC Biology Board questions · Chapter 12: Heredity in Organisms and Biological Evolution
What percentage of the children of couples M and N will be carriers?
Think it through first, then pick an option.
- a 25%
- b 50%
- c 75%
- d 100%
Answer and explanation
Correct answer: b 50%
In couple M (Rr × Rr) carrier children are 50%; in couple N all daughters, that is half the children, are carriers, 50%.
Why the other options are wrong
- a 25%: 25% is only the chance of a child with thalassemia; the carrier rate is different.
- c 75%: Not 75%; neither couple gives so many carriers.
- d 100%: Not 100%; not every child is a carrier. The right answer is 50%.
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