Which process ensures the maintenance of a specific type and a fixed number of chromosomes in organisms across generations?

The significance of meiosis is that it:

$A$: In higher organisms,a constant number of chromosomes is maintained generation after generation.
$R$: Meiosis occurs during the formation of gametes in plants and animals.

Meiosis is significant because

Find examples where the four daughter cells from meiosis are equal in size and where they are found unequal in size.

$A$: Meiosis is an important process for evolution. $R$: Crossing over induces genetic variation in a species.