Explain how equal genetic contribution of male and female parents is ensured in the progeny.

Equal genetic contribution of male and female parents is ensured in the progeny through the following biological mechanism:

1. Diploid Nature of Somatic Cells:

• Normal body cells (somatic cells) of sexually reproducing organisms are diploid ($2n$), meaning they contain two complete sets of chromosomes (one set inherited from the mother and one set from the father).

1. Reduction Division (Meiosis) during Gametogenesis:

• During the formation of germ cells (gametes), a special type of cell division called meiosis occurs.
• This process reduces the chromosome number by half. Thus, each gamete (sperm/pollen from the male parent and egg from the female parent) becomes haploid ($n$), containing only one chromosome from each pair (a single set of genes).

1. Fertilization Restores Diploidy:

• When fertilization takes place, the haploid male gamete ($n$) fuses with the haploid female gamete ($n$) to form a diploid zygote ($2n$).
• $$n \text{ (from father)} + n \text{ (from mother)} \longrightarrow 2n \text{ (zygote)}$$
• This restores the original chromosome number of the species in the offspring.

1. Equal Contribution:

• Since the zygote receives exactly one chromosome of each pair from the maternal gamete and the other from the paternal gamete, both parents contribute an equal amount of genetic material (DNA) to the progeny.