All human chromosomes are not paired. Most human chromosomes have a maternal and a paternal copy, and we…
All human chromosomes are 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.
Solution
(a) Zygote – 23 pairs / 46 chromosomes.
Gamete – 23 chromosomes.
(b) The temperature at which fertilised eggs are kept determines whether the animals developing in the eggs are male or female.
(c) [diagram: Sex determination in Human beings - Parents Father XY, Mother XX; gametes X,Y from father and X,X from mother combine to give XX FEMALE, XX FEMALE, XY MALE, XY MALE; 50% probability of a Female child, 50% probability of a male child]