What might happen if the gametes of a species had

the same number of chromosomes as the species'

body cells?

The chromosome number will not be constant and the person would die.

Explanation:

During gamete formation, half of the chromosomes arise from one parent and the other half from the other parent. This is possible due to the process of meiosis.

If during gamete formation, the number of chromosome does not get reduced, then after fertilization the gamete will have double the number of chromosomes as compared to the parents. Hence, the chromosome number of the person will not remain constant and he/she would die.