Question

A haploid parent produces gametes by mitotic division. Does this mean that meiosis never occurs in organisms that are haploid?

Answer 1

Cell division

1. The formation of daughter cells from parent cells is called cell division. It is of two types- mitosis and meiosis.
2. Mitosis refers to the replication of chromosomes to produce two identical daughter cells.
3. These cells consist of two sets of chromosomes, thus diploid in nature.
4. Meiosis refers to the reduction in the chromosome number resulting in the formation of four cells.
5. This type of cell division is seen in gametes- egg and sperm cells.
6. These cells consist of one set of chromosomes, thus haploid in nature.

Haploid organisms

1. Certain organisms have one set of chromosomes. Examples- Spirogyra and Volvox.
2. The fusion of haploid gametes results in the production of a diploid zygote.
3. These undergo meiosis resulting in the formation of haploid spores.
4. The haploid spores undergo mitotic division resulting in the formation of gametophytes.
5. In haploid organisms, the diploid stage is seen only in the zygote.