GRE Subject Test: Biology : Understanding Gametogenesis

Study concepts, example questions & explanations for GRE Subject Test: Biology

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Example Questions

Example Question #1 : Understanding Gametogenesis

What is a key difference between spermatogenesis and oogenesis?

Possible Answers:

Spermatogenesis results in only 1 sperm; oogenesis results in 2 eggs.

Spermatogenesis results in 8 sperm; oogenesis results in only 4 eggs.

Spermatogenesis results in 2 sperm; oogenesis results in only 1 egg.

Spermatogenesis results in 4 sperm; oogenesis results in only 1 egg.

Spermatogenesis results in only 1 sperm; oogenesis results in 4 eggs.

Correct answer:

Spermatogenesis results in 4 sperm; oogenesis results in only 1 egg.

Explanation:

During spermatogenesis, one spermatogonia will become 4 separate functioning spermatozoa. In oogenesis, a primary oocyte will become 1 functioning ovum (or egg) while 3 polar bodies are also produced, which are nonfunctioning and never become eggs.

Example Question #2 : Oogenesis And Spermatogenesis

When a female ovulates, in what phase of division is the oocyte?

Possible Answers:

Metaphase I

Prophase I

Metaphase II

Prophase II

Anaphase I

Correct answer:

Metaphase II

Explanation:

When a female ovulates, the oocyte is in metaphase II, until it becomes fertilized by a sperm. It then completes the second phase of meiosis to make a mature ovum. Remember that, unlike spermatogenesis, oogenesis begins during development. All oocytes undergo meiosis I during fetal development, and are kept suspended in prophase II until ovulation, when they shift to metaphase II. Meiosis only continues beyond metapahse II if fertilization occurs.

Example Question #32 : Biology

What is the "Dictyate state?"

Possible Answers:

Pre-vitellegenic stage in fetal development

A meiosis stabilizing factor 

An oogenetic ‘stasis’ between embryo and puberty

The state between fertilization and the start of gonadotropin production

The primordial follicle

Correct answer:

An oogenetic ‘stasis’ between embryo and puberty

Explanation:

Oogenisis halts in the female embryo while the oocytes are trapped in meiosis II. At the beginning of the menstrual cycle a number of oocytes in primordial follicles are stimulated by pituitary gonadotropins to continue maturation.

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