Which of the following types are meant for sex determination in animals?
A. In honey bee, sex determination in honey bee is based on the number of sets of chromosomes
B. In human, sex determination is XY type
C. In birds, sex determination is XO type
D. In grasshopper, sex determination is ZW type
Choose the correct type of sex determinations from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → A and B only
Sex determination is the way the sex of a new individual is fixed. In most animals it depends on sex chromosomes, but the system differs from group to group.
A. In honey bee, sex determination in honey bee is based on the number of sets of chromosomes — Correct. A fertilised egg has two sets (32 chromosomes) and becomes a female. An unfertilised egg has one set (16 chromosomes) and becomes a male. This is the haplodiploid system.
B. In human, sex determination is XY type — Correct. Human females are XX and males are XY.
C. In birds, sex determination is XO type — Incorrect. Birds have the ZW type. The females are ZW and the males are ZZ.
D. In grasshopper, sex determination is ZW type — Incorrect. Grasshoppers have the XO type. The females are XX and the males have only one X. Statements C and D have the two systems the wrong way round.
NCERT Extract:
Sex Determination in Honey Bee – “The sex determination in honey bee is based on the number of sets of chromosomes an individual receives.”
Sex Determination in Humans – “It has already been mentioned that the sex determining mechanism in case of humans is XY type.”
Sex Determination – “… Grasshopper is an example of XO type of sex determination in which the males have only one X-chromosome besides the autosomes, whereas females have a pair of X-chromosomes.”
Sex Determination – “… In these organisms the females have one Z and one W chromosome, whereas males have a pair of Z-chromosomes besides the autosomes.”