This set of Class 12 Biology Chapter 3 Multiple Choice Questions & Answers (MCQs) focuses on “Human Reproduction – Oogenesis”.
1. The onset of oogenesis occurs during _________
a) puberty
b) birth
c) adulthood
d) embryonic development
View Answer
Explanation: Oogenesis starts right from the embryonic development stage. Oogonia divide to form primary oocytes that are arrested at Prophase I.
2. What is the process of the formation of a mature female gamete called?
a) Menstruation
b) Spermatogenesis
c) Oogenesis
d) Ovulation
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Explanation: Spermatogenesis is the process of the production of mature sperms from spermatogonia, while oogenesis is the process of the formation of mature female gametes from oogonia.
3. What is the stage of the cell cycle at which primary oocytes are arrested?
a) Prophase I
b) Metaphase I
c) Prophase II
d) Metaphase II
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Explanation: Oogonia are formed during fetal development. Soon they start undergoing meiosis but are arrested at Prophase I awaiting further cues of division. Oogonia at this stage are called primary oocytes.
4. A person with tetraploidy will have _______ set of chromosomes in their first polar body.
a) haploid
b) triploid
c) diploid
d) polyploid
View Answer
Explanation: Oogenesis is the production of a haploid secondary oocyte from a diploid oogonium and in the process resulting in the production of two polar bodies, each of which is haploid. Naturally, a tetraploid person having tetraploid oogonia will produce diploid polar bodies and a diploid oocyte.
5. If a female is born with 6 million primary oocytes in each ovary, the maximum number of eggs that she can produce in her lifetime is 6 million.
a) True
b) False
View Answer
Explanation: Oogenesis begins with a single diploid oogonium arresting at Prophase I resulting in a primary oocyte. Each primary oocyte finishes the first round of meiosis to form one secondary oocyte and the first polar body. The secondary oocyte then undergoes a second round of meiosis to create one egg and a second polar body. And no more primary oocytes are added during the lifetime of the female. Instead, most primary oocytes degenerate as the female attains puberty. This limits the number of eggs that can be produced to less than 6 million.
6. The secondary oocyte has 46 chromatids, while the ovum has only 23 chromatids.
a) True
b) False
View Answer
Explanation: Secondary oocyte is formed after the first round of meiosis and thus has a haploid set of chromosomes i.e., 23 chromosomes. But each chromosome has two daughter chromatids, thus making a total of 46 chromatids. Ova are formed after the second round of meiosis, and each ovum gets a single chromatid, thus having a total of 23 chromatids.
7. The division of primary oocyte into the secondary oocyte and first polar body is an example of _______
a) symmetric division
b) asymmetric division
c) Cell death
d) asexual reproduction
View Answer
Explanation: Asymmetric division refers to the unequal distribution of cytoplasm between the daughter cells. Primary oocyte undergoes the first round of meiosis, producing a large haploid secondary oocyte and a tiny first polar body. Thus this is an instance of asymmetric division.
8. What are the cells that primary oocyte divides into called?
a) Secondary oocyte and first polar body
b) Secondary oocyte and second polar body
c) First polar body and second polar body
d) Ovum and second polar body
View Answer
Explanation: The primary oocyte is arrested at Prophase I of meiosis, and the division is completed only in the tertiary follicle. This division is asymmetric and produces a large haploid secondary oocyte and a small first polar body.
9. What are the cells that secondary oocyte divides into called?
a) Ovum and first polar body
b) Ovum and second polar body
c) First polar body and second polar body
d) Primary oocyte and second polar body
View Answer
Explanation: Secondary oocyte is formed as a result of the asymmetric division of primary oocyte, which also produces a tiny first polar body. Secondary oocyte further undergoes another asymmetric division producing a larger ovum and a smaller second polar body.
10. Which of the following is the correct set of ploidy and cell type?
a) Primary oocyte: Diploid; Secondary oocyte: Haploid; Ovum: Haploid
b) Primary oocyte: Haploid; Secondary oocyte: Haploid; Ovum: Haploid
c) Oogonium: Diploid; Primary oocyte: Diploid; Secondary oocyte: Diploid
d) Oogonium: Diploid; Primary oocyte: Haploid; Secondary oocyte: Haploid
View Answer
Explanation: The diploid oogonium goes through the first round of meiosis to form primary oocyte, which is arrested at Prophase I. Thus, the primary oocyte is also diploid. The division is completed after the formation of the secondary oocyte, which is haploid. The secondary oocyte undergoes another round of meiosis to form haploid ovum.
11. What stage is the oocyte released from the ovary?
a) Primary oocyte
b) Secondary oocyte
c) Tertiary oocyte
d) Ovum
View Answer
Explanation: Primary oocyte is formed during fetal development. The secondary oocyte is formed during puberty and is present in the ovary until it is released after the rupture of the Graafian follicle that holds it. Ovum is formed in the fallopian tube.
12. The membrane surrounding secondary oocyte is _______
a) Theca interna
b) Granulosa
c) Zona pellucida
d) Theca externa
View Answer
Explanation: Zona pellucida is a transparent extracellular matrix formed outside the secondary oocyte. It enhances interactions of egg with the follicle cells and also protects eggs during the development.
Sanfoundry Global Education & Learning Series – Biology – Class 12.
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