If a sperm carrying the Y chromosome takes part in fertilisation, what will be the sex-chromosome combination of the child?
Answer and explanation
Correct answer: XY, usually male
The human ovum normally contributes X, while a Y-bearing sperm contributes Y. Their fusion gives X + Y = XY, the usual male sex-chromosome combination. An X-bearing sperm would instead give X + X = XX, generally female. Only one sperm normally fuses with one ovum, so both combinations do not form together, and fertilisation does produce a definite chromosomal combination. Therefore option A is correct.
Frequently asked questions
What is the correct answer to this question?
XY, usually male
Why is this the correct answer?
The human ovum normally contributes X, while a Y-bearing sperm contributes Y. Their fusion gives X + Y = XY, the usual male sex-chromosome combination. An X-bearing sperm would instead give X + X = XX, generally female. Only one sperm normally fuses with one ovum, so both combinations do not form together, and fertilisation does produce a definite chromosomal combination. Therefore option A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Heredity and Evolution. Topic: Sex determination.
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