Why is it important to have the number of chromosomes when forming gametes?

Question

Why is it important to have the number of chromosomes when forming gametes?

Answer 1

"The" number?  Not sure exactly which number you mean.

In animals, each species has a set number of chromosomes for that species - for example humans have 23 in a set, and two sets (diploid) for a total of 46 chromosomes.  Different animals will have a dinnerent amount, but typically all are paired.

To form gametes, the cells divide in such a way that the number of chromosomes in the gamete are 1/2 the usual number - that way when fertilization occurs, the 1/2 from the monther and 1/2 from the father combine so the original number is maintained.

In plants, this is a little more complicated.  Plants are more likely to have polyploidy, or more than 2 sets of chromosomes - they can be triploid (3 sets) tetraploid (4 sets), pentaploid (5 sets) or even more.  So when a cell divides in "half" during meiosis, you don'y always get 1 set in each gamete - it can also 2+ sets in each.  Polyploidy seems to have little harmful effects in plants, but the same isn't true of animals.