Question

Haplodiploidy

9. Males bees are known to develop parthenogenically from unfertilized eggs and are therefore haploid. Females (both workers and queens) originate from fertilized (diploid) eggs. Sex chromosomes are not involed in this mechanism of sex determination which is characteristic of the insect order Hymenoptera. The quantity and quality of food available to the diploid larvae determine whether that female will become a sterile worker or a fertile queen. Thus environment here determines sterility or fertility but does not alter the genetically determined sex. The sex ratio of the offspring is under the control of the queen. Most of the eggs laid in the hive will be fertilized and develop into worker females. Those eggs which the queen chooses not to fertilize (from her store of sperm in the seminal receptacle) will develop into fertile haploid males. Queen bees usually mate only once during their lifetime. If the diploid number of the honey bee is 16,

(a) how many chromosomes will be found in the somatic cells of the drone,

(b) how many tetrads* will be seen during the process of gametogenesis in
*Recall that tetrad refers to synapsed homologues in prophase I.

(c) how many tetrads* will be seen during the process of gametogenesis in the female?

Answer 1

a) Somatic cell is all cells in body other than reproductive cells, so the Drone bee also called as male bee will have 8 chromosome because it is haploid and diploid number is 16.

b) Tetrads are the group of four chromosomes occurs in prophase 1 of meosis so males will not make any tetrads because they makes sperm by mitosis.

c) Females will make 8 sets of tetrads.