Here's why:

* Haploid means having only one set of chromosomes.

* Diploid means having two sets of chromosomes.

Sex cells, also known as gametes (sperm and egg), are involved in sexual reproduction. Their purpose is to combine with another gamete to form a zygote, which will develop into a new organism.

To maintain the correct number of chromosomes across generations, each gamete contributes only one set of chromosomes. This ensures that the zygote receives a complete set of chromosomes from both parents.