Question

Study the schematic cross between male and female honey bee given below and answer the questions that follow.

(a) Identify the cell division 'A' and 'B' that leads to gamete formation.

(b) Name the process 'C' that leads to development of honey bee.

(c) What type of sex-determination pattern is this ?

Hint:

Diploid queen makes eggs by meiosis, haploid drone makes sperms by mitosis, and unfertilised eggs develop by parthenogenesis (haplodiploidy).

Answer 1

Step 1: Read the diagram:
The female honey bee (queen) has 32 chromosomes, so she is diploid.
Her gametes can develop into a male without fertilisation (arrow C), or join with a male gamete to give a female with 32 chromosomes.
The male is produced from an unfertilised egg, so he is haploid with 16 chromosomes.

Step 2: (a) Cell divisions A and B:
A is meiosis, because the diploid female must halve her chromosome number to make eggs.
B is mitosis, because the male is already haploid, so his sperms are made by ordinary mitosis.

Step 3: (b) Process C:
C is parthenogenesis, the development of an egg into a new individual without fertilisation. This gives the male (drone).

Step 4: (c) Sex determination:
Sex depends on the number of chromosome sets. This is the haplodiploid system: fertilised eggs (diploid) become females, and unfertilised eggs (haploid) become males.

Final Answer:
(a) A = meiosis, B = mitosis. (b) C = parthenogenesis. (c) Haplodiploid sex-determination.