Question

All human chromosomes ate not paired. Most human chromosomes have a maternal and a paternal copy, and we have 22 such pairs. But one pair called the sex chromosomes, is odd in not always being a perfect pair. Women have a perfect pair of sex chromosomes. But men have a mismatched pair in which one is normal sized while the other is a short one.

(a) In humans, how many chromosomes are present in a Zygote and in each gamete?

(b) A few reptiles rely entirely on environmental cues for sex determination. Comment.

(c) "The sex of a child is a matter of chance and none of the parents are considered to be responsible for it." Justify it through flow chart only.

OR

(c) Why do all the gametes formed in human females have an X chromosome?

Answer 1

(a) Haplotype cells make up gametes. Only 23 chromosomes are present in each egg and sperm cell. That is a fraction of a cell's normal number of chromosomes. A diploid cell is created when two haploid cells fuse together. Zygote is a diploid cell, which means it has 46 chromosomes.

(b) Some animals (reptiles) completely rely on environmental signals to determine sex. The temperature at which fertilised eggs are stored determines whether the developing animal in the egg is male or female in some reptiles. Lizard used to be. Individuals in some species, such as the snail, can change sex in response to stress and environmental factors.

(c) The sex of a newborn child is purely and completely a matter of chance and none of the parent i.e. mother and father may be considered answerable for it. The statement in question is justified and can be proved by the process of fertilization:

                              OR

(c) The female human is homomorphic. They have identical copies of both sex chromosomes. Each gamete in meiosis receives one X chromosome at the moment of gamete creation. Thus, the X chromosome is present in all gametes.