Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

Read the following and answer any four questions from (i) to (v) given below:

The endosperm makes the main source of food for the embryo. Generally the endosperm nucleus divides after the division of the oospore, but in several cases the endosperm is formed to a great extent even before the first division of the oospore. There are three general types of endosperm formation: (a) nuclear type, (b) cellular type and (c) helobial type. The endosperm is usually triploid, but haploid endosperm is also found. Endosperm may either be completely consumed by the developing embryo before seed maturation, or it may persist in the mature seed.

1. Haploid endosperm is found in:

1. Pin us.
2. Cauliflower.
3. Sunflower.
4. Pea.

2. Persistent endosperm is found in:

P. Pea Q. Castor R. Bean S. Coconut T. Groundnut.

1. Q and S.
2. P and T.
3. R, S and T.
4. P, S and T.

3. Milk of tender coconut represents (A) and the surrounding white coconut meal represents (B).

S. No	A	B
(a)	Cellular endosperm	Free- nuclear endosperm
(b)	Free-nuclear endosperm	Cellular endosperm
(c)	Helobial endosperm	Cellular endosperm
(d)	Free-nuclear endosperm	Helobial endosperm

4. If an endosperm cell of a gymnosperm contains 12 chromosomes, the number of chromosomes in each cell of the root will be:

1. 4
2. 24
3. 16
4. 6

5. In angiosperms, normally after fertilization:

1. The zygote divides earlier than the primary endosperm nucleus.
2. The primary endosperm nucleus divides earlier than the zygote.
3. Both the zygote and primary endosperm nucleus divide simultaneously.
4. Both the zygote and primary endosperm nucleus undergo a resting period.

Read the following and answer any four questions from (i) to (v) given below:

A young couple married for 5 years is unable to bear a child in spite of not practicing any birth control method. Upon consultation, doctor advised them an assisted reproductive technology involving transfer of gametes into oviducts.

1. Identify the technique adopted by the couple.

1. ZIFT
2. JUI
3. GIFT
4. ICSI

2. What is the pre-requisite of this technique?

1. Gamete formation should be normal.
2. Fallopian tubes should be normal.
3. Female should have thick endometrial lining.
4. Male should be able to copulate the female.

3. Assertion: GIFT is an in-vitro fertilisation technique.

Reason: In GIFT, gametes are fertilised outside the female body.

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. The procedure advised to couple involves the transfer of:

1. Fertilised ovum.
2. Embryo with 8 blastomeres.
3. Sperms and unfertilised ovum.
4. Embryo with 16 blastomeres.

5. What is the success rate of this procedure?

1. 30-50%
2. < 20%
3. 80-85%
4. 27-30%

A regulatory body working under MoEF for the release of transgenic crop is ____________:

1. NBPGR
2. NSC
3. NIPGR
4. GEAC

Read the following and answer any four questions from (i) to (v) given below:
The foundations of recombinant DNA (rDNA) were laid by the discovery of restriction enzymes. These enzymes are present in many bacterias where they function as a part of their defense mechanism called the Restriction Modification system (RM system). Molecular basis of this system was explained first by Werner Arber in 1962. The Restriction Modification system consists of two components:

• A restriction enzyme (called restriction endonuclease) identifies the introduced foreign DNA and cuts it into pieces.
• The second component is a modification enzyme (methylase) that adds a methyl group to DNA at specific site to protect it from the restriction enzyme cleavage.

1. Restriction endonucleases are enzymes present in ________ where they function as a part of _______ mechanism.

1. (i) bacteria (ii) digestive
2. (i) protists (ii) transcription
3. (i) plant cells (ii) replication
4. (i) prokaryotes (ii) defence

2. Which of the following statements regarding modification enzyme is correct?

1. It adds methyl group to one or two bases usually within the host DNA sequence to protect it from the restriction enzyme.
2. It adds ethyl group to one or two bases usually within the sequence recognised by the restriction enzymes.
3. It adds methyl group to only one of bases within the foreign DNA sequence that is recognised by the restriction enzymes.
4. None of these.

3. Which of the following is a type II restriction enzyme?

1. Alu I
2. EcoR I
3. BamH I
4. All of these.

4. Which of the following is the first discovered restriction endonuclease?

1. Sal I
2. EcoR I
3. Hind II
4. EcoR II

5. Components of Restriction Modification System include?

1. Restriction enzyme.
2. Modification enzyme.
3. Lysing enzyme.
4. Both (a) and (b).

Read the following and answer any four questions from (i) to (v) given below:
Cross pollination is the transfer of pollen grains from the anther of a one flower to the stigma of a genetically different flower. It is performed with the help of an external agency which may be abiotic (e.g., wind, water) or biotic (e.g., insects, birds, bats, snails). The diagram shows the carpel of an insect pollinated flower.

1. What is the most likely reason for non germination of pollen grain Z?

1. Pollen grains X and Y were brought to the stigma earlier, therefore, their germination inhibited the germination of pollen grain Z.
2. Pollen grain Z was brought to the flower by wind, while pollen grains X and Y were brought to the flower by insect.
3. Pollen grain Z lacks protrusions that allow it to adhere properly onto the stigma surface.
4. Pollen grain Z comes from a flower of an incompatible species.

2. Which of the following best describes the function of the pollen tube?

1. It acts as a conduit to transport male gametes from the anther to the ovule.
2. It acts as a conduit to transport male gametes from the stigma to the ovule.
3. It contains key nutrients that serve to nourish the newly-formed zygote.
4. It digests the tissues of the stigma, style, and ovary.

3. Pollination of a flower in which the pollen is carried by an insect is called:

1. Anemophily.
2. Ornithophily.
3. Entomophily.
4. Malacophil.

4. Refer to the given characteristics of some flowers.

1. The stamens hang out of the flower, exposing the anthers to the wind.
2. The pollen grains are tiny and light.
3. The flower has a sweet scent.
4. The flower petals are brightly colored.

5. Pollenkitt is generally found in:

1. Anemophilous flowers.
2. Entomophilous flowers.
3. Ornithophilous flowers.
4. Malacophilous flowers.

Read the following and answer any four questions from (i) to (v) given below:
A 23 year old Sahil has been diagnosed with an infection of reproductive tract caused by bacteria. He complains about burning sensation during urination, pus-containing discharge and pain around genitalia. This infection has incubation period of 2-5 days but can be cured.

1. From which disease is Sahil suffering?

1. Chlamydiasis.
2. Herpes.
3. Gonorrhoea.
4. Syphilis.

2. Which among the following reproductive tract infections is transmitted by bacteria?

1. Trichomoniasis.
2. Chancroid.
3. Genital warts.
4. Both (a) and (b).

3. Which mode of treatment would be useful for Sahil?

1. Cryosurgery.
2. Use of Podophyllum preparation.
3. Use of antibiotic ampicillin.
4. It cannot be treated.

4. What technique was used to diagnose Sahil's disease?

1. Gram staining of discharge and culture.
2. ELISA Test.
3. Antibody detection.
4. Antigen test.

5. Find the odd one out.

1. Treponema pallidum.
2. Neisseria gonorrhoeae.
3. Haernophilus ducreyi.
4. Trichomonas vaginalis.

Read the following and answer any four questions from (i) to (v) given below:

Study the given table and answer the questions based on it.

	Hormone	Source	Function
(A)	Oxytocin	W	Ejection of milk
(B)	X	Anterior lobe of pituitary gland	Stimulates secretion of ABP from Sertoli cells
(C)	Y	Placenta	Maintains corpus luteum to secrete progesterone
(D)	Relaxin	Ovary	Z

1. Identify the hormones X and Y, respectively.

1. Testosterone, FSH.
2. LH, hPL.
3. FSH, hCG.
4. ICSH, hCG.

2. W in the given table is:

1. Hypothalamus.
2. Posterior lobe of pituitary.
3. Placenta.
4. Ovary.

3. Which of the following is correct for Z?

1. Dilation of uterine cervix during labour pains.
2. Stimulates the growth of the mammary glands during pregnancy.
3. Supports the fetal growth and prevents desiccation.
4. Forms protective plug in cervix of uterus during pregnancy.

4. Which set of hormones is secreted only during pregnancy?

1. Human chorionic gonadotropin, relax in and human placental lactogen.
2. Human placental lactogen, estrogen and chorionic thyrotropin.
3. Human chorionic gonadotropin, human placental lactogen and progesterone.
4. Chorionic thyrotropin, chorionic gonadotropin and estrogen.

5. Assertion: Follicle stimulating hormone controls the maintenance and functions of male reproductive organs.

Reason: FSH acts directly on spermatogonia to stimulate sperm production.

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.

Explain loss of biodiversity.

Explain different types of RNA along with process of transcription.

Read the following and answer any four questions from (i) to (v) given below:

Cleavage is the series of rapid mitotic divisions in zygote and forms blastula. The 2, 4, 8, 16 daughter cells are called blastomeres. Embryo with 64 blastomeres is known as blastocyst and has blastocoel cavity. Blastocyst gets implanted in uterine wall and leads to pregnancy.

1. Solid mass of cells with 16 blastomeres is called:

1. Morula.
2. Blastula.
3. Gastrula.
4. Zygote.

2. At which stage of embryonic development, trophoectoderm develops?

1. Zygote.
2. Morula.
3. Blastula.
4. Gastrula.

3. Site of implantation is:

1. Endometrium of uterus.
2. Cervix.
3. Uterine fundus.
4. Infundibulum of oviduct.

4. Correct sequence of various structures formed during embryonic development is:

1. Morula → Embryo → Gastrula → Blastula.
2. Zygote → Embryo → Morula → Blastula.
3. Blastula → Morula → Gastrula → Embryo.
4. Zygote → Morula → Blastula → Gastrula.

5. Assertion: Side of blastocyst with inner cell mass is called animal pole.

Reason: Inner cell mass gives rise to embryo.

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.