“The chromosomes number of the sexually reproducing parents and their offspring is the same.” Justify this statement.

The chromosome number of sexually reproducing parents and their offspring remains the same due to the following mechanisms:

1. Meiosis (Reduction Division): Organisms have specialized lineages of cells in reproductive organs that undergo a special type of cell division called meiosis. This process halves the number of chromosomes and the amount of DNA in the germ-cells (gametes) compared to the non-reproductive body cells (somatic cells). Thus, if the parent body cells have $2n$ chromosomes, the gametes will have only $n$ chromosomes.

1. Fertilisation: During sexual reproduction, the male gamete ($n$) and the female gamete ($n$) fuse to form a zygote. This fusion re-establishes the original diploid number of chromosomes ($2n$) and the original DNA content in the offspring. Therefore, the chromosome number remains constant from generation to generation.