Which of the following is correct regarding chromosomes?
A)At conception, the fertilized embryo has 48 chromosomes, 24 from the female egg and 24 from the male sperm.
B)The mother of an embryo always contributes a Y chromosome and the father always contributes an X chromosome.
C)Down syndrome results when chromosome 21 is present in triplicate instead of as the usual pair.
D)Chromosomes have no relationship to deoxyribonucleic acid (DNA).

Question

Quizplus · Accepted Answer

Down syndrome is caused by having three copies of chromosome 21 instead of the usual two. Option A is incorrect because at conception, a fertilized embryo has 46 chromosomes, 23 from the female egg and 23 from the male sperm. Option B is incorrect because the mother always contributes an X chromosome and the father can contribute either an X or Y chromosome. Option D is incorrect because chromosomes are made up of DNA.

Which of the Following Is Correct Regarding Chromosomes