Question Set D

CBSE 12th Standard Biology Principles of Inheritance and Variation HOT Questions Study Material - QB365

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Questions:

1 Marks

4 x 1 = 4

What is amniocentesis?

Name the common phenomenon with reference to reproduction in rotifers, honey bees and turkey.

Name an alga that reproduces asexually through zoospores. Why are these reproductive units so called?

How many pollen grains and ovules are likely to be formed in the anther and the ovary of an angiosperm bearing 25 microspore mother cells and 25 megaspore mother cells, respectively.

Generic 2

8 x 2 = 16

In our society, a woman is often blamed for not bearing a male child.Do you think it is right? Justify

Very briefly explain Linkage

What are two functions of DNA polymerase?

A man with blood group A married a woman with B group.They have a son with AB group and a daughter with blood group O.Work out and show the possibiliy of such inheritance

The human male never passes on the gene for haemophilia to his son.Why?

10.

Give an example of each type.
(i) Female XX with Male XO
(ii) Female ZW with Male ZZ.

11.

What is Pleiotropy? Give one example.

12.

Why is it difficuit to get rid of 'water hyacinth' from a water body? Name one abiotic component and one biotic component of the ecosystem that gets affected by its spread in the water body.

Generic 5

3 x 5 = 15

13.

(i) Explain the process of DNA replication with the help of a schematic diagram.
(ii) In which phase of the cell cycle does replication occur in eukaryotes? What would happen if cell division is not followed after DNA replication?

14.

Differentiate: (a)hypocotyl and epicotyl
(b) Coleoptile and coleorhiza
(c) Integument and testa
(d) Perispern and pericarp.

15.

(a) Describe in sequence the process of megasporogenesis in angiosperms.
(b) Draw the seven-celled structure formed and label all the different cells.

Generic 3

7 x 3 = 21

16.

With reference to a natural method of family planning, called lactational amenorrhea, answer the questions that follow:
(i) Is this a permanent method to avoid pregnancy?
(ii) Can Lactational amenorrhea be seen among oviparous organisms?
(iii) with respect to human health, what do you understand by the term the 'sterilization'?

17.

Classify the following contraceptive measures into different methods of birth control.
(i) Saheli
(ii) Tubectomy
(iii) Vasectomy
(iv) Condoms
(v) Diaphragms
(vi) Cervical caps

18.

Haemophilia is a sex linked recessive disorder of humans.The pedigree chart given below shows the inheritance of hemophilia in one family.study the pattern of inheritance and answer the questions given.

(a)Give all the possible genotype of the members 4,5 and 6 in the pedigree chart.recently married the member number 14.
What is the probability that first child will be a haemophilic male?

19.

Match the items in Column (A) with Column (B). Each point in column (A) has minimum one match in column (B) and maximum two matches.

Column (A)	Column (B)
1. Autogamy	(a) Megasporangia
2. Apomixis	(b) Xenogamy
3. Pollen sacs	(c) Female gametophyte
4. Ovules	(d) Asexual reproduction
5. Embryosac	(e) Allogamy
6. Pollar nuclei	(f) Secondary nucleus
7. Cross pollination	(g) Microsporangia
	(h) Agamospermy
	(i) Self pollination

20.

A smooth seeded and red flowered pea plant (Ss Rr) is crossed with a smooth seeded and white flowered pea plant(Ss rr).Determine the phenotype and genotypic ratios of the progeny\({ F }_{ 1 }\).

21.

Although potato tuber is an underground plant part, it is considered as a stem. Give two reasons.

22.

Study the pedigree chart given below showing the inheritance pattern of a human trait and answer the questions that follow:

(a) Give the genotype of the parents shown in generation I and of the son and daughter shown in generation II.
(b) Give the genotype of the daughter shown in generation III.
(c) Is the trait sex-linked or autosomal?Justify your answer.

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Answers Key:

1 Marks

4 x 1 = 4

()
Amniocentesis. A foetal sex determination test based on study of karyotype (chromosomal pattern) of the amniotic fluid present around developing foetus.

()
Reproduction

()
Chlamydomonas. The zoospores are motile (like animals).

()
100 pollen grains and 25 embryo sacs.

Generic 2

8 x 2 = 16

In our society a woman is often blamed for not bearing a male child.It is wrong because sex of child is determined by gametes formed by man who is heterogametic for sex chromosomes whereas woman is homogametic.

The tendency of the genes presents in the same chromosome to stay together in hereditary transmission is known as linkage.

DNA polymerase catalyses synthesis of DNA and help also in proof-reading

Male sex is determined by Y-Chromosome which does not bear the gene for haemophilia.

10.

(i) The type of sex-determination mechanism in which female XX with male XO is male heterogamety, e.g. grasshopper.
(ii) The type of sex-determination mechanism shown in female ZW with male ZZ is female heterogamety, e.g. birds.

11.

(a) Pleiotropic genes. When a single gene effect is expressed in a variety of characters although the primary effect is only one, such genes with multiple phenotypic effects are called pleiotropic genes.

The action of pleiotropic lethal gene can be illustrated with an example of sickle cell anaemia
Sickle cell Anaemia
1. It is caused by a mutant recessive allele on chromosome 11
2. The mutant gene causes the substitution glutamic acid (glu)by aline (val) at the sixth position of the beta globm of haemoglobin 3. The defective haemoglobin undergoes polymerisation under low oxygen tension and changes the shape of RBC from biconcave cells to sickle-shaped elongated cells.
4. The disease is controlled by a single pair of alleles, \(Hb^{ \wedge }\)and \(Hb^{ S }\)
5. Of the three possible genotypes, only individuals homozygous for \(Hb^{ S }\) show the disease, though heterozygous individuals (HbAHbS) are carriers,

12.

1. It is difficult to get rid of them because they propagate vegetatively at a rate faster than we could remove them.
2. It drains oxygen from the water.
3. It leads to fish mortality, i.e. death of fishes.

Generic 5

3 x 5 = 15

13.

(ii) DNA replication occurs in S-phase of cell cycle in eukaryotes.If cell division is not followed after DNA replication then the replicated chromosomes (DNA) would not be distributed to daughter nuclei. A repeated replication of DNA without any cell division results in the accumulation of DNA inside the cell.thereby causing cell expansion.

14.

(a) Hypocotyl and epicotyl. Hypocotyl is part of stem below cotyledons in the embryo of a plant and epicotyl is part of stem above cotyledons.
(b) Coleoptile and coleorhiza. Coleoptile is the sheath around the plumule. Coleorphiza is a sheath enveloping the radicle and root cap in certain plants.
(c) Integument and testa. Any protective covering around ovule is integument and testa is outer integument of seed coat.
(d) Perispern and pericarp. Pericarp is wall of ripened ovary of fruit and perisperm is remnant of nucellus in a seed.

15.

Development of Female Gametophyte:
- The megaspore mother cell undergoes meiosis to form four megaspores.
- Three of them degenerate and the functional megaspore enlarges to form the embryo sac.
- Its haploid nucleus undergoes a mitotic division and the two daughter nuclei move towards the poles.
- Each of them undergoes two successive mitotic divisions.
- Cell wall formation starts in the 8-nucleate stage.
- Three of them at the micropylar end form the egg apparatus, consisting of a female gamete and two synergids.
- Three of them at the chalazal end form the antipodal cells.
- One nucleus from each of the poles moves to the centre; they are called polar nuclei.
- The two polar nuclei fuse in the centre (now the central cell) to form a diploid secondary nucleus.
- Thus, the mature embryo sac is 7-celled and 8-nucleate.

Generic 3

7 x 3 = 21

16.

(i) No, lactational amenorrhea is a temporary contraceptive method based on natural infertility resulting from certain patterns of breastfeeding.
(ii) Lactational amenorrhea is the characteristics of breastfeeding mother only.
(iii) Sterilization is the permanent method of birth control. It includes surgical methods. i.e. tubectomy in females and vasectomy in males. These techniques are highly effective but their reversibility is very poor.

17.

(i) Oral pills
(ii) Surgical method
(iii) Surgical method
(iv) Barrier method
(v) Barrier method
(vi) Barrier method

18.

(a) Member 4 = Female = 22 + XX
Member 5 = Affected male = 22 + X^hY
Member 6 = Male = 22 + XY
(b) Member 14 is a carrier female (XX^h) who got married with member 15 (XY) A cross between two results:

The probability is 25% haemophilic male.

19.

1.(i); 2. (d), (h), 3. (g); 4. (a); 5. (c); 6.(f) ; 7.(b), (e)

20.

Phenotypes Smooth seeded X and red flowered Smooth seeded and
Parents SsRr White flowered SsRr
Genotype

21.

(i) The tuber has nodes and internodes.
(ii) Leafy shoots appear from the nodes.

22.

(a) Genotype of the parents in generation I:
Male (Father) - Aa'
Female (Mother) - Aa Son (Generation II) - Aa Daughter (Generation II) - aa
(b) Genotype of the daughters in generation III - Aa
(c) It is an autosomal trait, because if the sex-linked trait has to appear in the daughter (generation II), the father must have it; but he does not show the trait and so it is not sex-linked.