Question Set B

CBSE 12th Standard Biology Sexual Reproduction in Flowering Plants Sample Question Papers Study Material - QB365

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Questions:

1 Marks

20 x 1 = 20

Write the function of RNA polymerase II.

Name the enzyme and the direction in which it catalyses the polymerisation of ribonucleotides.

What is a nucleoid?

In which position is the phosphate group linked to a nucleosid? Name the linkage too.

Name any two hormones found in the blood of a pregnant female only.

How are different varieties of pollen grains stored for long period of time in pollen banks?

Which one is removed during splicing-introns or exons?

The plant Yucca and moth cannot complete their life cycle without each other. Why?

In the following figure of a fruit, label the part that is protective in function and the part that is responsible for producing new plants

10.

PCR requires very high temperature conditions where most of the enzymes get denatured. How was this problem resolved in a PCR ?

11.

State the function of trophoblast in human embryo.

12.

Give the term used for the age at which the reproductive organs become functional?

13.

Why are pollen grains produced in enormous quantity in Maize?

14.

What will happen if the fallopian tubes are partially blocked and the ovulated eggs are prevented from reaching the uterus?

15.

When was the Human Genome Project launched and when was it completed?

16.

In some viruses DNA is synthesised using RNA template. What term is given to such a DNA?

17.

What is the disadvantage of continued self-pollination in plants?

18.

Name the tallest flower.

19.

Why is the middle piece of human sperm considered as 'powerhouse of the sperm'?

20.

Name the protective substance present in the pollen envelope to tide over adverse conditions.

Multiple Choice Question

19 x 1 = 19

21.

Which layer of embryo is formed first

(a)

Ectoderm

(b)

Mesoderm

(c)

Endoderm

(d)

Both 2 and 3

22.

What is true about cleavage ?

(a)

size of embryo increases

(b)

size of cells decreases

(c)

size of cells increases

(d)

size of embryo decreases

23.

A female undergo hysterectomy, which one of the following event will not occur?

(a)

Formation of Graafian follicle

(b)

Ovulation

(c)

Menstruation

(d)

Completion of meiosis-I and formation of secondary oocyte

24.

Select the correct option describing hormonal activity in a nonpregnant woman.

(a)

Surge of FSH at the middle of menstrual cycle stimulates ovulation

(b)

During follicular phase, regeneration of endometrium is mainly due to progesterone

(c)

High levels of oestrogens from almost mature follicle inhibit release of GnRH

(d)

FSH and LH stimulate development of ovarian follicle and secretion of oestrogens from it

25.

Mature Graafian follicle is generally present in the ovary of a healthy human female aroundstet

(a)

5-8 day of menstrual cycle

(b)

11-17 day of menstrual cycle

(c)

18-23 day of menstrual cycle

(d)

24- 28 day of menstrual cycle

26.

Which of the following statements are correct:
Statement I: During the growth of embryo limbs and external genital organ is formed by the ends of 12 weeks.
Statement II: The sex of the developing embryo can be determined using ultra sonography after 3 months of pregnancy.

(a)

Statement II is correct but statement I is incorrect

(b)

Both 'statements are correct

(c)

Both statements are incorrect

(d)

Statement I is correct but statement II is incorrect.

27.

When pollen grains of a flower fall on the stim of another flower of the same Plant this condition is called

(a)

Genetically self-pollination

(b)

Genetically self-pollination and ecologicaly cross pollination

(c)

Ecologically cross pollination

(d)

Genetically cross pollination and ecologically self-pollination

28.

Observe structures A and B given below. Which of the following statements are correct?

(a)

A is having 2-OH group which makes it less reactive and structurally stable, whereas Bis having 2-H group which makes it more reactive and unstable

(b)

A is having 2-OH group which makes it more reactive and structurally unstable, whereas Bis having 2-H group which makes it less reactive and structurally stable

(c)

A and B both have-OH groups which make it more reactive and structurally stable

(d)

A and B both are having-OH groups which make it less reactive and structurally stable

29.

The net electric charge on DNA and histone, is

(a)

positive, negative

(b)

negative, positive

(c)

negative, negative

(d)

positive, positive.

30.

In the lac operon of E.coli, the i gene codes for

(a)

inducer

(b)

repressor

(c)

lactase

(d)

\(\beta\)-galactosidase

31.

The cell which undergoes meiosis I during spermatogenes, is the

(a)

spermatogonium

(b)

spermatid

(c)

primary spermatocyte

(d)

secondary spermatocyte

32.

Match the terms in Column I with the descriptions in Column II.

Column I	Column II
A. Syncarpous ovary	1. Occurrence of more than one embryo in a seed
B. Polyembryony	2.Carpels in a flower are fused together
C. Apomixis	3. Removal of stamens from the bisexual flower bud
D. Emasculation	4. Formation of seeds without fertilisation.
	5. Development of ovary into fruit without fertilisation.

(a)

A - 4, B - 1, C - 2, D - 3

(b)

A - 2, B - 1, C - 4, D - 3

(c)

A - 2, B - 4, C - 1, D - 3

(d)

A - 3, B - 1, C - 4, D - 2

33.

PCR and Restriction Fragment Length polymorphism are the methods for:

(a)

Study of enzymes

(b)

Genetic transformation

(c)

DNA sequencing

(d)

Genetic fingerprinting

34.

Which one of the following palindromic base sequences in DNA can be easily cut at about the middle by some particular restriction enzyme.

(a)

5' CACGTA 3';3' CTCAGT 5'

(b)

5' CGTTCG 3';3' ATGGTA 5'

(c)

5' GATATC 3';3' CTACTA 5'

(d)

5' GAATTC 3';CTTAAG 5'

35.

Nitrogenous bases present present in DNA

(a)

Adenine Guanine Cytosine, Thiamine

(b)

Adenine Guanine Cytosine Uracil

(c)

Adenine Thiamine Uracil

(d)

Guanine and Uracil

36.

Which one of the following statements is wrong?

(a)

When pollen is shed at two-celled stage, double fertilization does not take place

(b)

Vegetative cell is larger than generative cell

(c)

pollen grains in some plants remain viable for months

(d)

Intine is made up of cellulose and pectin

37.

An organic substance that can withstand environmental extremes and cannot be degraded by any enzyme is:

(a)

Cuticle

(b)

Sporopollenin

(c)

Lignin

(d)

Cellulose

38.

Selaginella and Salvinia are considered to represent a significant step towards evolution of seed habit because

(a)

female gametophyte is free and gets dispersed like seeds

(b)

female gametophyte lacks archegonia

(c)

megaspores posses endosperm and embryo surrounded by seed coat

(d)

embryo develop in female gametophyte which is retained on the parent sporophyte

39.

In DNA replication, leading strand replicates in

(a)

5' ------>3' direction continuously

(b)

3'------>5' direction continuously

(c)

5'----->3' directiom discontinuosly

(d)

3,------->5' direction discontinuously

True or False

11 x 1 = 11

40.

Termination / Stop codons do not have any tRNAs

(a)

True

(b)

False

41.

If a double-stranded DNA contains 20% cytosine, it will have 20% guanine in it.

(a)

True

(b)

False

42.

VNTR belongs to a class of satellite DNA, called microsatellite.

(a)

True

(b)

False

43.

The process of translation of mRNA begins, when the mRNA encounters the large subunit of ribosome.

(a)

True

(b)

False

44.

Polycistronic mRNA is generaUy found in eukaryotes.

(a)

True

(b)

False

45.

Relaxin is the hormone secreted by the placenta.

(a)

True

(b)

False

46.

The finger-like projections that appear on the trophoblast following implantation, are called chorionic villi.

(a)

True

(b)

False

47.

Oxytocin, necessary for parturition, is secreted by the fully-developed foetus and the placenta.

(a)

True

(b)

False

48.

Meiosis does not occur in the organisms showing haplontic life cycle.

(a)

True

(b)

False

49.

Embryo sac ⇾ Nucellus ⇾ Integuments, is the correct sequence of parts in the ovule of an angiosperms.

(a)

True

(b)

False

50.

Sepals and petals or perianth are inconspicuous in entomophilous flowers.

(a)

True

(b)

False

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Answers Key:

1 Marks

20 x 1 = 20

()
It transcribes hnRNA, the precursor of mRNA, in eukaryotes.

()
(i) DNA-dependent RNA-polymerase.
(ii) 5' ➝ 3' direction.

()
Nucleoid is the region in prokaryotic cells where DNA is organised as large loops held by some positively charged proteins.

()
1. A phosphate group is linked to the 5' -OH of a nucleoside.
2. Phosphoester linkage

()
Relaxin and human chorionic gonadotropin.

()
The pollen grains can be stored for years in liquid nitrogen (-196°C) in pollen banks and used for crop breeding programmes.

()
Introns.

()
The moth deposits its eggs in locule of ovary and flower, in turn, gets pollinated by the moth.

()

10.

()
The use of a thermostable DNA polymerase Thermus aquaticus which remain active during the high temperature induced denaturation of double stranded DNA.

11.

()
Trophoblast forms chorionic villi, which become part of the placenta.

12.

()
Puberty

13.

()
Maize plants are pollinated by wind (Anemophilous) and it is the property of wind pollinated flowers to produce enormous quantity of small pollen grains to ensure pollination.

14.

()
Fertilisation may take place but the zygote may develop in the tube instead of uterus.

15.

()
HGP was launched in 1990 and it was completed in 2003.

16.

()
Complementary DNA (cDNA)

17.

()
Continued self-pollination results in homozygosity and inbreeding depression.

18.

()
Flowers of Amorphopallus (6-feet in height).

19.

()
Middle piece contains numerous mito-chondria,which produce energy for the movement of sperm for the movement of sperm for fertilisation;so it is called the power house.

20.

()
Sporopollenin.

Multiple Choice Question

19 x 1 = 19

21.

22.

(b)
size of cells decreases

23.

24.

(d)
FSH and LH stimulate development of ovarian follicle and secretion of oestrogens from it

25.

(b)
11-17 day of menstrual cycle

26.

(b)
Both 'statements are correct

27.

28.

(b)
A is having 2-OH group which makes it more reactive and structurally unstable, whereas Bis having 2-H group which makes it less reactive and structurally stable

29.