Mitosis and meiosis in hybrid animals

Question

Consider two closely related species—Species A and Species B. Species A and B will mate with each other in captivity, and often produce healthy offspring. However, the hybrid offspring are usually sterile, because Species A has 12 pairs of chromosomes and Species B has 11 pairs of chromosomes. Explain what occurs during mitosis and during meiosis in the hybrid that allows normal development and growth from zygote to adult, but causes the adults to be sterile. (As part of your explanation, can you create diagrams of the chromosome arrangements for both mitosis and meiosis using the same number of chromosomes given to you in this question?)

Answer 1

In mitosis, DNA is simply doubled and travels to either new cell. In meiosis, DNA is first doubled. Then tetrads are formed. A tetrad contains the duplicated and analogous DNA from both parents and its where crossover occurs. However, if parents don't have same number of chromosomes tetrads cant usually form because every chromosomes from one parent must find a chromosome from other parent. With no tetrad and recombination, everything else fails.

Here is useful picture comparing 2;: https://kaiserscience.files.wordpress.com/2015/01/meiosis_vs-_mitosis1315851705371.png