Question

Male sex is determined in human zygote by.
A.Nutrition of mother
B.Strength of father
C.Chromosome composition of egg
D.Chromosome composition of sperm

Answer 1

We know that a zygote is a eukaryotic cell (nucleus is enclosed by the nuclear membrane) which is formed by the union of a male (sperm) and a female (ova) gamete. These gametes are the reproductive cells of organisms. The genetic constitutional chromosome of the female gamete (ova) is the ‘X’ chromosome. In other words, the female gamete always carries the X chromosome. Whereas, the sperm can carry either the ‘X’ chromosome or the ‘Y’ chromosome.

Complete answer:
1.We have already discussed the ova and the sperm along with their chromosomes.
2.We know that the ova carries the ‘X’ chromosome whereas the sperm can carry either ‘X’ or ‘Y’ chromosome.
3.If the sperm carries the ‘X’ chromosome, it will fuse with the ‘X’ chromosome of the ova, the sex of the child will be female. In other words, a female child will be expected if the ‘X’ chromosomes of both ova and sperm fuse. The chromosome thus formed will be an ‘XX’ chromosome. It is the most common gender type for females.
4.On the other hand, a male child will be born if the sperm carries a ‘Y’ chromosome. Then, it will go on to fuse with the ‘X’ chromosome of the ova and will form an ‘XY’ chromosome. 5.This is the most common gender type for males.
6.We can see that the sex of the zygote depends on the chromosome composition of sperm.
7.Thus, the male sex is determined in human zygote by the chromosome composition of the sperm.
8.Factors like ‘Nutrition of mother’ and ‘Strength of father’ have nothing to do with the sex of the zygote. So, the first two options are wrong.
9.And, the third option is wrong because the ovum carries only one chromosome.
10.Therefore, the correct answer to this question is option D.

| Male Chromosome (Either X or Y)
---|---
Female Chromosome (Only X) | X| Y
X| XX| XY
| Female Child| Male Child

Hence, the correct answer is option (D)

Note: The method that we studied above is known as the XY sex-determination system. It is used to classify many mammals, including humans, some insects, snakes, fish and some plants. Here, a pair of chromosomes are used to determine the sex of the offspring.