Biology · Principles of Inheritance and Variation · NEET
No. This is the point students miss most. Honey bees do NOT use sex chromosomes (no X or Y). Sex is decided by the number of chromosome SETS. A fertilised egg (two sets, diploid) becomes a female. An unfertilised egg (one set, haploid) becomes a male. This system is called haplodiploidy.
By parthenogenesis. This means the egg develops into a new individual without any sperm joining it. In honey bees, an unfertilised egg develops directly into a male drone. So the male has no father, only a mother (the queen).
Females (queen and workers) are diploid with 32 chromosomes (2n). Males (drones) are haploid with 16 chromosomes (n). So the male has HALF the chromosome number of the female. NEET has asked exactly this fact.
A drone has NO father because he comes from an unfertilised egg (only a mother). But he does have a grandfather, because his mother (the queen) came from a fertilised egg and so had a father. This 'no father, but has a grandfather' point is a favourite trick idea.
A drone is already haploid (16 chromosomes). Meiosis would halve the number again, which the cell cannot afford. So drones make sperm by MITOSIS, not meiosis. This keeps the sperm haploid (16). Females still make eggs by normal meiosis. Statement 'males produce sperms by meiosis' is FALSE in NEET questions.
Both queen and worker are diploid females from fertilised eggs, so genetics does not decide it. DIET decides it. A larva fed royal jelly becomes a fertile queen; larvae fed normal food become sterile workers. This is a diet (environmental) effect, not a chromosome effect.
Which of the following statements are true with reference to the sex-determination in honeybees? A. An offspring formed from the union of a sperm and an egg, develops as a female (queen or worker). B. An unfertilized egg develops as a male by parthenogenesis. C. A male has half the number of chromosomes than that of a female. D. Males produce sperms by meiosis. E. Honeybees have a haplodiploid sex-determination system. Choose the correct answer from the options given below:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Because one sex is haploid and the other is diploid. Males are haploid (n = 16) and females are diploid (2n = 32). Joining the words haploid and diploid gives haplodiploid.
A drone's sperm can fertilise the queen's eggs, so he has daughters (fertilised eggs = females). But he cannot have sons, because sons come from unfertilised eggs which never involve his sperm.
No. In XO, both sexes are diploid and differ by one sex chromosome. In haplodiploidy there are no sex chromosomes at all; the sexes differ in the whole number of chromosome sets (haploid vs diploid).
The female needs fertilisation. A fertilised egg gives a female (queen or worker). The male drone comes from an unfertilised egg, so it does not need fertilisation.
