Question 1

1. In an angiosperm, the innermost wall layer of the microsporangium that provides nourishment to the developing pollen grains is called:

A) EndotheciumB) Middle layersC) TapetumD) Epidermis

Answer

✓ Correct Answer: Option C

Explanation: The microsporangium has four wall layers: epidermis, endothecium, middle layers, and tapetum. The **Tapetum** is the innermost layer and its primary function is to nourish the developing pollen grains.

Question 2

2. If the haploid number of chromosomes in a flowering plant is n = 12, what will be the ploidy and chromosome number of the endosperm after triple fusion?

A) Diploid, 24B) Triploid, 36 Tetraploid, 48

Question 3

3. Which part of the mammalian sperm contains a high concentration of mitochondria to provide energy for motility?

A) Middle pieceB) HeadC) AcrosomeD) Tail

Answer

✓ Correct Answer: Option A

Explanation: The **Middle piece** of the sperm contains numerous mitochondria, which produce energy in the form of ATP for the movement of the tail, facilitating sperm motility.

Question 4

4. A mature embryo sac in a typical angiosperm is described as:

A) 8-celled, 7-nucleateB) 7-celled, 7-nucleateC) 8-celled, 8-nucleateD) 7-celled, 8-nucleate

Answer

✓ Correct Answer: Option D

Explanation: At maturity, a typical angiosperm embryo sac (Polygonum type) consists of 7 cells (3 antipodals, 2 synergids, 1 egg cell, and 1 large central cell) but contains 8 nuclei because the central cell has two polar nuclei.

Question 5

5. The surge of which hormone is directly responsible for the process of ovulation in the human menstrual cycle?

A) ProgesteroneB) Luteinizing Hormone (LH)C) EstrogenD) Follicle Stimulating Hormone (FSH)

Answer

✓ Correct Answer: Option B

Explanation: Both LH and FSH attain a peak level in the middle of the cycle (about $14^{th}$ day). Rapid secretion of **LH** leading to its maximum level during the mid-cycle (LH surge) induces the rupture of Graafian follicle and release of ovum (ovulation).

Question 6

6. The hard outer layer of the pollen grain called exine is composed of a highly resistant organic material known as:

A) SporopolleninB) CelluloseC) PectinD) Lignin

Answer

✓ Correct Answer: Option A

Explanation: **Sporopollenin** is one of the most resistant organic materials known. It can withstand high temperatures and strong acids and alkalies. No enzyme that degrades sporopollenin is so far known.

Question 7

7. In human females, where does the fertilization of the ovum by the sperm normally occur?

A) UterusB) CervixC) Ampullary-isthmic junctionD) Vagina

Answer

✓ Correct Answer: Option C

Explanation: Fertilization in humans takes place in the fallopian tube, specifically at the **ampullary-isthmic junction** (or simply the ampulla).

Question 8

8. What is the function of Filiform apparatus located at the micropylar part of the synergids?

A) To prevent polyspermyB) To guide the entry of pollen tubeC) To provide nutrition to the eggD) To help in the formation of endosperm

Answer

✓ Correct Answer: Option B

Explanation: The synergids have special cellular thickenings at the micropylar tip called the **filiform apparatus**, which play a crucial role in guiding the pollen tubes into the synergid.

Question 9

9. Leydig cells, found in the interstitial spaces of the testes, are responsible for the secretion of:

A) Androgens (Testosterone)B) EstrogensC) InhibinD) Oxytocin

Answer

✓ Correct Answer: Option A

Explanation: **Leydig cells** (interstitial cells) synthesize and secrete testicular hormones called androgens, primarily testosterone.

Question 10

10. Which of the following depicts the correct pathway of sperm transport in the male reproductive system?

A) Rete testis → Vasa efferentia → Vas deferens → EpididymisB) Epididymis → Rete testis → Vasa efferentia → Vas deferensC) Vasa efferentia → Rete testis → Epididymis → Vas deferensD) Rete testis → Vasa efferentia → Epididymis → Vas deferens

Answer

✓ Correct Answer: Option D

Explanation: The seminiferous tubules open into the **rete testis**, which leads to **vasa efferentia**. These open into the **epididymis** located along the posterior surface of each testis, which then leads to the **vas deferens**.

Question 11

11. Double fertilization is a unique characteristic of angiosperms. It involves:

A) Fusion of two eggs with two spermB) Syngamy and Triple FusionC) Fusion of sperm with synergid and antipodalD) Two sperm fusing with one egg

Answer

✓ Correct Answer: Option B

Explanation: **Double fertilization** involves two types of fusion in the embryo sac: Syngamy (fusion of one male gamete with the egg to form a zygote) and Triple Fusion (fusion of the second male gamete with two polar nuclei to form the primary endosperm nucleus).

Question 12

12. In human embryonic development, the blastocyst becomes embedded in the layer of the uterus called the:

A) PerimetriumB) MyometriumC) EndometriumD) Ectoderm

Answer

✓ Correct Answer: Option C

Explanation: Implantation occurs when the blastocyst becomes embedded in the **endometrium**, the innermost glandular layer of the uterus.

Question 13

13. Persistent nucellus in some seeds (like Black Pepper and Beet) is known as:

A) PerispermB) EndospermC) PericarpD) Scutellum

Answer

✓ Correct Answer: Option A

Explanation: In some seeds, remnants of the nucellus are persistent. This residual, persistent nucellus is called the **perisperm**.

Question 14

14. The process of formation of a mature female gamete (ovum) is called oogenesis. At which stage is oogenesis initiated in human females?

A) At PubertyB) During MenopauseC) During MenstruationD) During Embryonic development

Answer

✓ Correct Answer: Option D

Explanation: Oogenesis is initiated during the **embryonic development** stage when a couple of million gamete mother cells (oogonia) are formed within each fetal ovary; no more oogonia are formed and added after birth.

Question 15

15. Cleistogamous flowers are those which:

A) Always perform cross-pollinationB) Have colorful petals to attract insectsC) Do not open at allD) Require water for fertilization

Answer

✓ Correct Answer: Option C

Explanation: **Cleistogamous** flowers do not open at all. In such flowers, the anthers and stigma lie close to each other, ensuring autogamy (self-pollination).

Question 16

16. The first milk produced by the mother during the initial few days of lactation, which contains antibodies (IgA) essential for the newborn, is:

A) SerumB) ColostrumC) PlacentaD) Lactose

Answer

✓ Correct Answer: Option B

Explanation: The milk produced during the initial few days of lactation is called **colostrum** which contains several antibodies absolutely essential to develop resistance for the new-born babies.

Question 17

17. If a pollen grain has 20 chromosomes, how many chromosomes will be present in the generative cell and the tube cell respectively?

A) 20, 20B) 20, 40C) 10, 10D) 40, 20

Answer

✓ Correct Answer: Option A

Explanation: Both the generative cell and the tube cell are formed by the mitotic division of the haploid microspore (n). Therefore, they both contain the same number of chromosomes as the pollen grain. If the pollen grain is n=20, both cells have 20 chromosomes.

Question 18

18. Which of the following is NOT a function of the placenta in humans?

A) Supply of oxygen and nutrients to the fetusB) Removal of carbon dioxide and excretory wastesC) Secretion of Oxytocin during parturitionD) Secretion of Estrogen and Progesterone

Answer

✓ Correct Answer: Option C

Explanation: The placenta facilitates the supply of oxygen and nutrients and the removal of wastes. It also acts as an endocrine tissue (secreting hCG, hPL, estrogens, progesterones). **Oxytocin** is secreted by the maternal posterior pituitary, not the placenta.

Question 19

19. The part of the ovary that acts as a temporary endocrine gland after ovulation and secretes progesterone is the:

A) Primary follicleB) Corpus luteumC) Corpus albicansD) Stroma

Answer

✓ Correct Answer: Option B

Explanation: After ovulation, the remaining parts of the Graafian follicle transform into the **corpus luteum**. The corpus luteum secretes large amounts of progesterone which is essential for maintenance of the endometrium.

Question 20

20. Wind pollinated (anemophilous) flowers usually have:

A) Large, brightly colored petalsB) Heavy and sticky pollen grainsC) Abundant nectar productionD) Light and non-sticky pollen grains

Answer

✓ Correct Answer: Option D

Explanation: Wind pollination requires the pollen grains to be **light and non-sticky** so that they can be transported in wind currents. They often possess well-exposed stamens and large feathery stigmas to trap air-borne pollen grains.

Accepted Answer

✓ Correct Answer: Option B

Explanation: Triple fusion involves the fusion of one male gamete (n) with two polar nuclei (forming a secondary nucleus, 2n). The resulting Primary Endosperm Nucleus (PEN) is triploid (3n). If n=12, then $3n = 3 \times 12 = 36$.

Grade 12 : Biology - Sexual Reproduction Quiz (Set 1)

1. In an angiosperm, the innermost wall layer of the microsporangium that provides nourishment to the developing pollen grains is called:

2. If the haploid number of chromosomes in a flowering plant is n = 12, what will be the ploidy and chromosome number of the endosperm after triple fusion?

3. Which part of the mammalian sperm contains a high concentration of mitochondria to provide energy for motility?

4. A mature embryo sac in a typical angiosperm is described as:

5. The surge of which hormone is directly responsible for the process of ovulation in the human menstrual cycle?

6. The hard outer layer of the pollen grain called exine is composed of a highly resistant organic material known as:

7. In human females, where does the fertilization of the ovum by the sperm normally occur?

8. What is the function of Filiform apparatus located at the micropylar part of the synergids?

9. Leydig cells, found in the interstitial spaces of the testes, are responsible for the secretion of:

10. Which of the following depicts the correct pathway of sperm transport in the male reproductive system?

11. Double fertilization is a unique characteristic of angiosperms. It involves:

12. In human embryonic development, the blastocyst becomes embedded in the layer of the uterus called the:

13. Persistent nucellus in some seeds (like Black Pepper and Beet) is known as:

14. The process of formation of a mature female gamete (ovum) is called oogenesis. At which stage is oogenesis initiated in human females?

15. Cleistogamous flowers are those which:

16. The first milk produced by the mother during the initial few days of lactation, which contains antibodies (IgA) essential for the newborn, is:

17. If a pollen grain has 20 chromosomes, how many chromosomes will be present in the generative cell and the tube cell respectively?

18. Which of the following is NOT a function of the placenta in humans?

19. The part of the ovary that acts as a temporary endocrine gland after ovulation and secretes progesterone is the:

20. Wind pollinated (anemophilous) flowers usually have: