Question

Describe haplodiploid sex-determination system in honey bees.

Answer 1

The sex in humans is determined by the presence or absence of X or Y sex chromosomes in the males. But in the case of honeybees, evolution has resulted in a unique way of the sex-determination system. The system of determination of sex in Honey bees is known as the Haplodiploidy system.

Complete answer:
Haplodiploidy is defined as the biological system of sex determination as where unfertilized haploid eggs develop into males and fertilized eggs, into females. It is found in Hymenopterans (Honey bees).
Determination of Sex
• The sex-determination system determines the sexual characteristics of an organism.
• The sex of an organism can be determined externally (e.g. by environmental and social variables) or genetically.
• Sex determination is determined genetically in most of the species.
• The genetic system includes the following-
• Chromosomal systems- XX/XY sex-determination system,
• Y-centered sex determination,
• X-centered sex determination,
• X0 sex-determination system,
• ZW sex-determination system, and
• haplodiploidy.
Haplodiploidy system is a biological system of sex determination where unfertilized haploid(n) eggs develop into males and fertilized eggs, into females.
For example, the queen honeybee would have three types of offspring based on their social function:
• female worker bees,
• male drones, and
• the new queen bee.
• The new queen bee and the female worker bee develop from fertilized eggs and are therefore diploid.
• However, the female worker bees would become sterile.
• The unfertilized eggs develop into male drones by undergoing a process called parthenogenesis, and they are haploid individuals.

Note:
Haplodiploidy sex determination system is not the same thing as an ${X_0}$ sex-determination system.
The males receive one-half of the chromosomes than females receive, including autosomes in case of haplodiploidy whereas in ${X_0}$ sex-determination system, males and females receive an equal number of autosomes, but when it comes to sex chromosomes, females will receive two X chromosomes while males will receive only a single X chromosome.