Sex of an individual is determined by different factors in various species. Some animals rely entirely on…
Sex of an individual is determined by different factors in various species. Some animals rely entirely on the environmental cues, while in some other animals the individuals can change their sex during their life time indicating that sex of some species is not genetically determined. However, in human beings, the sex of an individual is largely determined genetically.
(a) In what way are the sex chromosomes 'X' and 'Y' different in size ? Name the mismatched pair of sex chromosome in humans.
(b) Write the number of pair/pairs of sex chromosomes present in human beings. In which one of the parent (male / female) perfect pair / pairs of sex chromosomes are present ?
(c) Citing two examples, justify the statement "Sex of an individual is not always determined genetically".
Solution
(a)
X chromosome is of normal size and Y chromosome is short / Y chromosome is shorter than X chromosome.
XY pair of chromosomes
(b)
One pair of sex chromosomes
mother/female has perfect pair of chromosomes
(c)
In reptiles, the temperature at which fertilized eggs are kept determines whether the animals developing in the eggs would be a male or a female.
In snails, they can change their sex during their lifetime.