How do the chromosomes in most cells of an organism, such as the leaf cells of a plant, compare to the chromosomes in its reproductive cells, which are sperm and egg cells?

The chromosomes in all the cells of the body, except for the sex cells, are diploid in number. The somatic cells divide by the process of mitosis.

The chromosomes in the sex cells are haploid and divide by the process of meiosis. This is because when an egg cell and a sperm cell will join, then each half of the chromosomes present in both the cells will pair up to maintain the chromosome number of the species.