Question

Hybrid animals are usually, but not always sterile. a mule is the offspring of a horse and a donkey. a donkey sperm contains 31 chromosomes and a horse egg contains 32 chromosomes, resulting in a zygote with 63 chromosomes that can develop normally. discuss why mitosis can occur normally in a mule but meiosis not.

Answer 1

This is because mitosis does not change the zygosity of the cell but only replicates the genetic material before separation o daughter cells. However, meiosis halves the zygosity of the parent cell (by separating homologous sister chromosomes) hence the daughter cells must have equal numbers of chromosomes (n). Meiosis will, therefore, be difficult in mule due to the abnormal number of chromosomes (odd numbered) hence resulting in the unequal division of the chromosomes during meiosis during the making of sperm or egg cells.