1. At what point in development do the oogonia divide into haploid cells? Select

Question

1. At what point in development do the oogonia divide into haploid cells? Select one:

a. After puberty, one per month

b. During childhood

c. During the embryonic stage of pregnancy

d. During the fetal stage of pregnancy

2. How many polar bodies are made if fertilization occurs? Select one:

a. 1

b. 3

c. 2

d. 4

3. What structure develops in the ovary from the remnants created after ovulation? Select one:

a. The corpus luteum

b. The primary follicle

c. The primary oocyte

d. The secondary follicle

4. Why do males have to create so many sperm for successful reproduction? Select one:

a. Many sperm are necessary for fertilization to occur

b. Sperm are energy-intensive to make

c. Most sperm are lost or die once in the female tract

d. Most sperm are lost or die before making it out of the male tract

5. Why does spermatogenesis only begin at puberty? Select one:

a. Hormonal signals do not trigger the sex drive necessary for spermatogenesis

b. Testosterone is destroyed by the body before puberty starts

c. The testes do not begin producing a significant quantity of testosterone before that point

d. The testes have not descended into the scrotu until puberty

Explanation / Answer

1. At what point in development do the oogonia divide into haploid cells?

a. After puberty, one per month

Note: Oogenesis or the process of differentiation of ovum or egg cell, starts before the the girl child has even born. During oogenesis the primary oocytes are formed during the embryonic development. Upto fetal formation all the primary oocytes have been formed and all are arrested in meiosis I (diploid). Once the girl is born and hit their puberty, one single primary oocyte decides to form secondary oocyte (haploid) per ovarian cycle. So the diploid to haploid transition occurs after puberty.

2. How many polar bodies are made if fertilization occurs?

b. 3

Note: During primary oocyte to secondary oocyte formation of oogenesis process or in continuation of meiosis I, one primary oocyte gives rise to one secondary oocyte and one polar body. Then the secondary oocyte stops at meiosis II in metaphage state. When the fertilization occurs the secondary oocyte will continue to finish meiosis II and mature into ovum and produce one polar body. Also the polar body from previous step complete meiosis II and produces two more polar body. So in total three polar bodies are formed after fertilization. The first polar body may or maynot divide, so it always depend how many polar body will generate at the end.

3. What structure develops in the ovary from the remnants created after ovulation?

a. The corpus luteum

Note: Corpus luteum is formed during the luteal phase, after a secondary oocyte is released from the ovarian follicle, and this remnants of follicle is converted into an endocrine struture. This is a temporary structure and release progesterone during pregnancy.

4. Why do males have to create so many sperm for successful reproduction?

c. Most sperm are lost or die once in the female tract

Note: Men releases about 50 million of sperms per ejacuation. Among them only one millinon can reach upto uterus. Uterus is very hostile for sperms, as the acidic conditions can kill many of the sperms, the mucosal layer of uteral wall entraps many sperms. So about 100 to 200 sperms can reach to fallopian tube where a very few can find an egg. So to increase the chance of fertilization male produces so many sperms.

5. Why does spermatogenesis only begin at puberty?

c. The testes do not begin producing a significant quantity of testosterone before that point

Note: Before puberty male can not produce testosterone in sufficient amount. Insufficient testosterone doesn't allow spermatogenesis upto prophage stage of meosis I. After puberty when Follicle stimulating hormone and Luteinizing hormones are starting to produce, leydig cells of testes produce testosterone as an effect. Once the level of the hormone reach to sufficent amount the spermatogenesis completes.

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