Biology, Eighth Edition (Raven)

Chapter 52: The Reproductive Systems

Spermatogenesis

What is the difference between sperm and egg cells? Gametes are haploid cells used in sexual reproduction. Plants and animals and many other organisms produce two types of gametes – eggs and sperm. Eggs are large gametes that are not capable of active movement and have substantial amounts of nutrients. Sperm are small gametes that are capable of movement in most organisms although not in flowering plants. A system with two different types of gametes seems to be the most efficient. Eggs provide nutrients necessary for the developing embryo. As eggs are relatively expensive to make, there are relatively few of them. Sperm are small and therefore easy to make in the large numbers needed to ensure fertilization. Not all sexual organisms have eggs and sperm. Many fungi and some algae are isogamous. All of their gametes are equal in size and there are no males and females in the sense that we normally think of the two sexes.

View the animation below, then complete the quiz to test your knowledge of the concept.


1.	Spermatogenesis occurs in the

		A)	epididymis.
		B)	seminiferous tubules.
		C)	prostate gland.
		D)	vas deferens.
		E)	seminal vesicle.

2.	Which of the following is a correct sequence of cells in spermatogenesis?

		A)	spermatogonium -> primary spermatocyte -> secondary spermatocyte
		B)	spermatogonium -> secondary spermatocyte -> primary spermatocyte
		C)	primary spermatocyte -> secondary spermatocyte -> spermatogonium
		D)	primary spermatocyte -> spermatogonium -> secondary spermatocyte
		E)	none of the above

3.	During spermatogenesis, which of the following cells is the first to become haploid?

		A)	primary spermatocyte
		B)	secondary spermatocyte
		C)	sperm cells
		D)	spermatid
		E)	spermatogonium

4.	Meiosis II of spermatogenesis results in the formation of secondary spermatocytes.

		A)	True
		B)	False

5.	During spermatogenesis, spermatids differentiate into spermatozoa.

		A)	True
		B)	False