AP BIOLOGY

Detailed explanation-1: -This is because the sperm provides almost no cytoplasm (and hence no mitochondria) to the fertilized egg. The egg has thousands of mitochondria and it is these that are passed to the developing embryo.”

Detailed explanation-2: -The egg contributes all the cytoplasm and organelles to the zygote. The sperm only contributes one set of chromosomes. The sperm and egg each have only half the number of chromosomes as other cells in the body.

Detailed explanation-3: -Like a sperm cell, the egg contains a nucleus with half the number of chromosomes as other body cells. Unlike a sperm cell, the egg contains a lot of cytoplasm, the contents of the cell, which is why it is so big. The egg also does not have a tail.

Detailed explanation-4: -It was believed that the spermatozoon’s only contribution to the embryo formation was its genome. In recent times, extensive studies have shown that the spermatozoon contribution is substantial; it contributes both its DNA and its entire structure to embryo formation [4].

Detailed explanation-5: -In the head of most animal sperm, closely apposed to the anterior end of the nuclear envelope, is a specialized secretory vesicle called the acrosomal vesicle (see Figure 20-25). This vesicle contains hydrolytic enzymes that may help the sperm to penetrate the egg’s outer coat.