AP Biology : Understanding Gametogenesis

Study concepts, example questions & explanations for AP Biology

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Example Question #1 : Understanding Gametogenesis

Which answer best explains why each primary spermatocyte cell (2n) results in the eventual production of four spermatids (n), while each oogonium cell (2n) results in the eventual production of only one active egg cell (n)?

Possible Answers:

None of the other answers are correct

During spermatogenesis, the cellular material is divided evenly during meiosis I and II, resulting in four equally sized spermatids. During oogenesis, only one of the two daughter cells that results from meiosis I passes through meiosis II; the other daughter cell remains dormant. Of the daughter cells that result from meiosis II, one becomes an active egg cell while the other disintegrates.

During spermatogenesis, the cellular material is divided evenly during meiosis I and II, resulting in four equally sized spermatids. During oogenesis, both meiosis I and meiosis II involve the uneven distribution of cytoplasm, which results in only one active egg cell and two or three polar bodies.

During spermatogenesis, the cellular material is divided evenly during meiosis I and II, resulting in four equally sized spermatids. During oogenesis, the process of meiosis results in four potential active egg cells of equal size and functionality; arbitrarily, three of these cells are degraded, leaving only active egg cell.

Correct answer:

During spermatogenesis, the cellular material is divided evenly during meiosis I and II, resulting in four equally sized spermatids. During oogenesis, both meiosis I and meiosis II involve the uneven distribution of cytoplasm, which results in only one active egg cell and two or three polar bodies.

Explanation:

Spermatogenesis is a continuous process starting at puberty. Sperm production takes place in the seminiferous tubules. There, each spermatogonium cell (2n) divides equally via mitosis to produce two identical primary spermatocytes (2n). Each primary spermatocyte undergoes meiosis I to produce two equally sized secondary spermatocytes (n). Each secondary spermatocyte then undergoes meiosis II to produce a total of four spermatids (n). The spermatids differentiate before moving to the epididymis.

Oogenesis, on the other hand, begins prior to birth and is a stop-start process. While still within the embryo, each oogonium (2n) produces two identical primary oocytes (2n) via mitosis; the primary oocytes remain dormant in small ovarian follicles until puberty. After the onset of puberty, hormones periodically stimulate the follicles to complete meiosis I and produce secondary oocytes (n). It is important to note, however, that meiosis I produces only one secondary oocyte—the other "daughter cell" is actually the first polar body, which is almost always rapidly degraded (though sometimes this polar body also undergoes meiosis II and produces a third polar body). This occurs because the primary oocyte divides unevenly, leaving the secondary oocyte with virtually all of the cytoplasm during cytokinesis. Secondary oocytes are released during ovulation, but they do not complete meiosis II until fertilization, when they are penetrated by a sperm. Meiosis II results in another polar body, again due to uneven division of cytoplasm during cytokinesis. 

Example Question #2 : Understanding Gametogenesis

Which term refers to the formation of egg cells that begins in the developing ovaries of a female fetus?

Possible Answers:

Ovulation

Mitosis

Fertilization

Oogenesis

Meiosis

Correct answer:

Oogenesis

Explanation:

The mature human ovum is formed through the developmental process known as oogenesis, which takes place during the first three months of fetal development. Ovarian follicles each contain one oogonium, which becomes a primary oocyte, then a secondary oocyte. No further division occurs until puberty.

Mitosis is a type of nuclear division in which one copy of each chromosome moves into each of two daughter nuclei to create identical daughter cells. Meiosis is also a type of cell division, in which a diploid cell divides twice to produce four haploid cells. Ovulation is the release of the secondary oocyte from the ovary, and fertilization is the union of a male sperm and female egg to produce a zygote. 

Example Question #3 : Understanding Gametogenesis

Spermatogenesis is the production of sperm by the process of __________, followed by differentiation.

Possible Answers:

meiosis

mitosis

proliferation

migration

gametogenesis

Correct answer:

meiosis

Explanation:

During spermatogenesis, spermatogonia become primary spermatocytes, then seconday spermatocytes. These divide to form two spermatids, which transform into functional spermatozoa. Through the process of meiosis, the chromosome number is reduced from the diploid number (46) to the haploid number (23).

Mitosis refers to the replication of somatic cells, creating identical daughter cells from a diploid parent. Migration occurs as the spermatogonia, spermatocytes, and spermatids move from the outermost edge of the seminiferous tube to the central cavity of the tuble. Proliferation is the repeated reproduction of new parts. Gametogenesis is defined as the development of gametes. 

Example Question #1557 : Ap Biology

Mitosis and meiosis differ in that mitosis produces __________ cells with __________ genetic material, whereas meiosis produces __________ cells with __________ genetic material.

Possible Answers:

2 . . . a unique mixture of . . . 2 . . . identical

2 . . . identical . . . 4 . . . identical

4 . . . a unique mixture of . . . 2 . . . identical

2 . . . identical . . . 4 . . . a unique mixture of

Correct answer:

2 . . . identical . . . 4 . . . a unique mixture of

Explanation:

During mitosis cells divide a single time and retain the exact same genetic material, producing two identical copies of the parent cell. During meiosis, cells divide twice and cross over during anaphase I. This produces a unique combination of chromosomes (recombinants) not seen in the parent cell.

Example Question #4 : Understanding Gametogenesis

In humans the gametes are produced in __________.

Possible Answers:

Mitochondria 

Somatic cells

The zygote

The gonads

Correct answer:

The gonads

Explanation:

Gametes are the haploid sex cells that are produced in the gonads (ovaries in females and testes in males). These are the primary sex organs.

Example Question #5 : Understanding Gametogenesis

A human cell from the ovary has 22 chromosomes and an X chromosome. It is __________.

Possible Answers:

a muscle cell

a somatic cell

an ovum 

a sperm

Correct answer:

an ovum 

Explanation:

A cell with 22 chromosomes and 1 sex chromosome is clearly haploid (n=23) and so it must be a sex cell and not a somatic cell (2n=46). Since both male and female gametes may contain an X chromosome, that information is not enough to tell us whether this cell comes from a male of female. However, since we are told the cell came from the ovary, we know it is the female gamete, an ovum. A muscle cell is a type of somatic cell, all of which are diploid.

Example Question #6 : Understanding Gametogenesis

Which of the following is not a true characteristic of gametocytes?

Possible Answers:

They are eukaryotic somatic cells

Gametocytes can divide by mitosis into other gametocytes

Male gametocytes are called spermatocytes

Female gametocytes are called oocytes

Correct answer:

They are eukaryotic somatic cells

Explanation:

Gametocytes are eukaryotic germ line cells. They can undergo mitosis to form more gametocytes or undergo meiosis to form gametids. Male gametocytes are called spermatocytes and female gametocytes are called oocytes.

Example Question #7 : Understanding Gametogenesis

Which of the following best describes the difference between a primary and secondary spermatocyte?

Possible Answers:

The secondary spermatocyte is diploid and the primary spermatocyte is haploid

The secondary spermatocyte forms during meiosis II and the primary spermatocyte forms during mitosis

The secondary spermatocyte forms during mitosis and the primary spermatocyte forms during meiosis II

The secondary spermatocyte is haploid and the primary spermatocyte is diploid

Correct answer:

The secondary spermatocyte is haploid and the primary spermatocyte is diploid

Explanation:

Spermatocytes are male gametocytes located in the seminiferous tubules of the testes. Primary spermatocytes are diploid and form when spermatogonia—immature germ cells—enter into mitosis. Primary spermatocytes can then enter meiosis and produce haploid secondary spermatocytes after meiosis I.

Example Question #8 : Understanding Gametogenesis

Which of the following is not a true characteristic of spermatogonia?

Possible Answers:

They develop into primary spermatocytes through mitosis

They are germ line cells

They are haploid

They are undifferentiated

Correct answer:

They are haploid

Explanation:

Spermatogonia are diploid undifferentiated male germ cells located in the seminiferous tubules of the testes. Spermatogonia are important in the process of spermatogenesis; they turn into primary spermatocytes via growth and maturation.

Example Question #9 : Understanding Gametogenesis

Which of the following terms is best defined as a mature, motile, and haploid sperm cell produced during spermatogenesis?

Possible Answers:

Spermatozoa

Spermatid

Spermatogonium

Secondary spermatocyte

Correct answer:

Spermatozoa

Explanation:

Mature sperm cells that are haploid, motile, and produced during spermatogenesis are called spermatozoa. Spermatids are haploid; however, they are immature. Spermatids will turn into spermatozoa once they mature.

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