Reproduction in Lower and Higher Plants — BIOLOGY STD 12 Science — Question

Read the following and answer any four questions from (i) to (v) given below:
Pollen-pistil interaction is the group of events that occur from the time of pollen deposition over the stigma to the time of pollen tube entry into ovule. It is a dynamic process which has checks at several places for promotion or inhibition of pollen growth. Pollen-pistil interaction is a safety measure to ensure that illegitimate crossings do not occur. Compatibility and incompatibility of the pollen-pistil is determined by special proteins. The compatible pollens are able to absorb water and nutrients from the surface of the stigma. They germinate and produce pollen tubes. Pollen tubes grow into the style. Their growth and path through the style are also determined by specific chemicals.

1. Which of the following parts of gynoecium determines the compatible nature of pollen?

1. Stigma.
2. Style.
3. Ovary.
4. Thalamus.

2. In Triforium, which type of self-incompatibility is found?

1. Gametophytic self-incompatibility (GSI).
2. Sporophytic self-incompatibility (SSI).
3. Both GSI and SSI.
4. None of these.

3. Select the incorrect statement.

1. In Asteraceae, incompatibility is due to the genotype of the sporophytic stigmatic tissues.
2. In members of Brassicaceae, incompatibility is due to the genotype of the pollen.
3. Nature has imposed self-incompatibility to avoid highly homozygous individuals, which have a very low survival value.
4. None of these.

4. Which of the following are examples of self incompatibility?

1. Tobacco.
2. Potato.
3. Crucifers.
4. All of these.

5. Given figures show the pollen-stigma interaction, where pollen wall proteins are released onto the pellicle of stigmatic papillae, where a recognition reaction occurs.

Which of the following statements drawn from given figures is incorrect?

1. P indicates compatible reaction in which the pollen tube penetrates the cuticle and grows down the papilla.
2. Development of callose plug between the plasma membrane and pectocellulosic layer of stigmatic papillae results in the incompatibility reaction in Q.
3. A callose plug, which appears at the tip of pollen in Q, is dissolved by callase enzyme secreted by stigma resulting in compatibility reaction.
4. Deposition of callose can be employed as a reliable bioassay to detect compatibility or incompatibility reactions of pollen and stigma.

Distinguish between: Euchromatin and Heterochromatin.

Distinguish between : Extero and entero receptors.

Ectomycorrhizae and Endomycorrhizae.

Distinguish between : Atrio ventricular valves and Semilunar valves.

Read the following and answer any four questions from (i) to (v) given below:
In testis, the immature male germ cells produce sperms by spermatogenesis that begins at puberty. It occurs in the seminiferous tubules of the testes. Seminiferous tubules are lined by germinal epithelium. Study the schematic representation of spermatogenesis and answer the following questions.

1. Which cell division occurs during multiplication phase?

1. Mitosis.
2. Meiosis I.
3. Meiosis II.
4. Both (b) and (c).

2. How many chromosomes are present in secondary spermatocyte and spermatid, respectively?

1. 46, 23
2. 46, 46
3. 23, 23
4. 23, XY

3. Transformation of L into M is known as:

1. Spermiation.
2. Spermateliosis.
3. Spermatogenesis.
4. None of these.

4. Select the correct option.

1. Type A spermatogonia grows to larger primary spermatocyte.
2. One spermatogonium forms two spermatids.
3. Spenniation is the release of sperms from seminiferous tubules.
4. Primary spermatocyte undergoes mitosis to form secondary spermatocytes.

5. Which hormone acts on spermatogonia to stimulate sperm production?

1. LH.
2. GnRH.
3. ABP.
4. FSH.

Match the layer of adrenal with its hormone.

Column A (Layers of adrenal cortex)	Column B (Hormones)
(1) Zona glomerulosa	(A) Cortisols
(2) Zona fasciculata	(B) Androgens
(3) Zona reticularis	(C) Aldosterone

Read the following and answer any four questions from (i) to (v) given below:
During copulation, semen is released by the penis into the vagina. 'The motile sperms swim rapidly, fuse with ovum in the ampullary region, resulting in fertilisation. Haploid nucleus of sperm fuse with that of ovum to form diploid zygote.

1. In female genital tract, sperms are made capable of fertilising the egg. This phenomenon of sperm activation is called:

1. Amphimixis.
2. Cortical reaction.
3. Capacitation.
4. Acrosomal reaction.

2. Select the correct sequence of various physical and chemical events that take place during fertilisation.

16. Fusion of cortical granules with plasma membrane of secondary oocyte.
17. Formation of fertilisation cone to receive sperm.
18. Release of sperm lysin from acrosome.
19. Mixing up of chromosomes of a sperm and an ovum.

1. R → Q → P → S
2. Q → S → R → P
3. Q → R → S → P
4. R → P → Q → S

3. Assertion: Only one sperm can fertilise an ovum.

Reason: The secretion of acrosome help the sperm to enter into cytoplasm of ovum through zona pellucida and plasma membrane.

1. Both assertion and reason are true, and reason is the correct explanation of assertion.
2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
3. Assertion is true, but reason is false.
4. Both assertion and reason are false

4. What is the significance of fertilisation?

1. It restores haploid number of chromosomes.
2. It produces offspring genetically identical to parents.
3. It initiates cleavage.
4. Both (b) and (c).

5. Site of fertilisation in humans is:

1. Endometrium of uterine cavity.
2. Ampullary isthmic junction of oviduct.
3. Cervix of uterus.
4. Infundibulum of fallopian tube.

Distinguish between : Ascariasis and Filariasis.

A patient is suffering from ADA deficiency. Can he be cured? How?