AP BIOLOGY

Detailed explanation-1: -Although all sperm may look the same to a casual observer in fact human ejaculates are very heterogeneous, and subpopulations of sperm with distinct biochemical and physiological characteristics can be identified in every sample.

Detailed explanation-2: -Like your genome, each gamete is unique, which explains why siblings from the same parents do not look the same. Following fusion of the egg and sperm, another type of cell division called mitosis occurs, producing two identical cells from one.

Detailed explanation-3: -There are two types of sperm cells: X sperm and Y sperm. X sperm: X sperm on combining with the X chromosome of the female produces a zygote with XX chromosomes.

Detailed explanation-4: -Occasionally, two sperm are known to fertilize a single egg; this ‘double fertilization’ is thought to happen in about 1% of human conceptions. An embryo created this way doesn’t usually survive, but a few cases are known to have made it-these children are chimaeras of cells with X and Y chromosomes.