Question Set D

cbse 12th Standard Biology Sexual Reproduction in Flowering Plants Important Questions And Answers Study Material - QB365

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Questions:

Generic 3

4 x 3 = 12

Is sex education necessary in schools? Why?

Do you think that reproductive heath in our country has improved in the past 50 years? If yes, mention some such areas of improvement.

What are the measures one has to take to prevent from contracting STDs?

Suggest the aspects of reproductive health which need to be given special attention in the present scenario.

Generic 5

4 x 5 = 20

What is oogenesis? Give a brief account of oogenesis.

(a) Humans reproduce ____________.(asexually / sexually)
(b) Humans are ____________.(oviparous, viviparous, ovoviviparous)
(c) Fertilisation is ____________.in humans. (external/internal)
(d) Male and female gametes are ____________. (diploid/haploid)
(e) Zygote is ____________. (diploid/haploid)
(f) The process of release of ovum from mature follicle is called ____________.
(g) Ovulation is induced by a hormone called ____________.
(h) The fusion of male and female gametes is called ____________.
(i) Fertilisation takes place in ____________.
(j) Zygote divides to form ____________. which is implanted in uterus.
(k) The structure which provides vascular connection between foetus and uterus is called ____________.

Identify True/False statements. Correct each false statement to make it true:
(a) Androgens are produced by Sertoli cells. (True/False)
(b) Spermatozoa get nutrition from Sertoli cells. (True/False)
(c) Leydig cells are found in ovary. (True/False)
(d) Leydig cells synthesise androgens. (True/False)
(e) Oogenesis takes place in corpus luteum. (True/False)
(f) Menstrual cycle ceases during pregnancy. (True/False)
(g) Presence or absence of hymen is not a reliable indicator of virginity or sexual experience. (True/False)

(a) Name the phase preceded and followed by ovulation in a menstrual cycle.Explain the events occurrung during these phases.

(b) Explain the role of pituitary hormones in the regulation of menstrual cycle.

Multiple Choice Question

21 x 1 = 21

Menstrual cyclc, in thc human femalc, is completed in:

(a)

30 days

(b)

31 days

(c)

28 days

(d)

27 days.

10.

Identify the correct labellings in the figure of a fertilised embryo sac of an angiosperm given below.

(a)

A-Zygote, B-Degenerating synergids, C-Degenerating antipodals, D-PEN

(b)

A- Degenerating synergids, B- Zygote, C-PEN, D-Degenerating antipodals

(c)

A-Degenerating antipodals, B-PEN, C-Degenerating synergids, D-Zygote

(d)

A-Degenerating synergids, B-Zygote, C-Degenerating antipodals, D-PEN

11.

The periodic abstinence by a couple for family planning should be from

(a)

day 5 to 10 of menstrual cycle

(b)

day 13 to 15 of menstrual cycle

(c)

day 10 to 17 of menstrual cycle

(d)

day 16 to 20 of menstrual cycle

12.

Select the option that has the correct sequence of events of human female reproductive cycle.
(i) Secretion of FSH
(ii) Ovulation
(iii) Growth of corpus luteum
(iv) Growth of follicle and oogenesis
(v) Sudden increase in LH

(a)

i-iii-v-iv-ii

(b)

i-iv-v-ii-iii

(c)

iv-i-v-iii-ii

(d)

v-ii-iii-iv-i

13.

Which of the following statements are true related to seed X and Y ?

(i) Seed X is dicot and endospermic or albuminous.
(ii) Seed X is dicot and non-endospermic or non-albuminous.
(ii) Seed Y is monocot and endospermic or albuminous.
(iv) Seed Y is monocot and non-endospermic or non-albuminous.
Choose the correct option with respect to the nature of the seed.

(a)

(i) and (iii)

(b)

(ii) and (iii)

(c)

(i) and (iv)

(d)

(ii) and (iv)

14.

Select the option that shows the correctly identified U, X, Y and Z in a developing dicot embryo.

(a)

X-Plumule (2n), Y-Suspensor (n), Z-Cotyledon (2n), U-Radicle (2n)

(b)

X-Plumule (2n), Y-Suspensor (2n), Z-Radicle (2n), U-Cotyledon (2n)

(c)

X-Suspensor (2n), Y-Cotyledon (2n), Z-Radicle (2n), U-Plumule (2n)

(d)

X-Cotyledon (2n), Y-Radicle (n), Z-Plumule (n), U-Suspensor (n)

15.

Choose the correct labellings for the parts X, Y and Z in the given figure of the stages in embryo development in a dicot.

(a)

X is suspensor, Y is radicle and Z is cotyledon

(b)

X is radicle, Y is cotyledon and Z is suspensor

(c)

X is cotyledon, Y is suspensor and Z is radicle

(d)

X is zygote, Y is radicle and Z is cotyledon

16.

To overcome incompatible pollinations so as to get desired hybrids, a plant breeder must have the knowledge of __________ .

(a)

pollen-nucellar interaction

(b)

pollen-egg cell interaction

(c)

pollen-pistil interaction

(d)

pollen-embryo sac interaction

17.

Signals from fully developed foetus and placenta ultimately lead to parturition, which is facilitated by the release of

(a)

oestrogen from placenta

(b)

oxytocin from maternal pituitary

(c)

oxytocin from foetal pituitary

(d)

maternal progesterone

18.

Concentration of which of the following substances will decrease as in the maternal blood it flows from embryo to placenta through the umbilical cord?

(i) Oxygen
(ii) Amino acids
(iii) Carbon dioxide
(iv) Urea

(a)

(i) and (ii)

(b)

(ii) and (iv)

(c)

(ii) and (iv)

(d)

(i) and (iv)

19.

Anthesis is a phenomenon which refers to

(a)

Formation of pollen

(b)

Development of anther

(c)

the opening of a flower bud

(d)

Reception of pollen by stigma

20.

Devices for self-pollination are

(a)

Dicliny or unisexuality

(b)

Dichogamy

(c)

heterostyly

(d)

None of these

21.

Pollen grains are able to withstand extremes of temperature and desiccation because their exine is composed of

(a)

Cutin

(b)

Suberin

(c)

Sporopollenin

(d)

Callose

22.

The plant part which consists of two generations one within the other is

(a)

Germinated pollen grain

(b)

seed

(c)

Unfertilized ovule

(d)

Embryo

23.

Pick the odd one out

(a)

Chalazogamy

(b)

Porogamy

(c)

Mesogamy

(d)

Allogamy

24.

In a flowering plant, archesporium gives rise to

(a)

only the wall of the sporangium

(b)

both wall and the sporogenous cells

(c)

wall and the tapetum

(d)

Only tapetum and sporogenous cells

25.

Insect-pollinated flowers are characterized by

(a)

Large number of pollens

(b)

Dry and smooth pollens

(c)

Sticky and rough pollens

(d)

Heavy pollens

26.

In angiosperms, pollen tubes liberate their male gametes into the

(a)

Central cell

(b)

Antipodal cell

(c)

Egg cell

(d)

Synergids

27.

Which type of association is found in between entomophilous flower and pollinating agent?

(a)

Mutualism

(b)

Commensalism

(c)

Cooperation

(d)

Coevolution

28.

Intraspecific incompatibility can be overcome by

(a)

Wetting of anthers

(b)

Mixed pollination

(c)

Intraovarian fertilization

(d)

Intraspecific competition

29.

Egg apparatus consists of

(a)

egg

(b)

egg and polar nuclei

(c)

Egg and synergids

(d)

Egg and antipodal cells

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Answers Key:

Generic 3

4 x 3 = 12

Yes, sex education is necessary in schools because
(i) The children should know about sex-related issues and problems like adolescence changes, menstrual cycle, menstrual problems, unwanted pregnancy, unsafe abortion, reproductive tract infections, STDs and cancer.
(ii)They should be aware of changes happening in their body and should be taught about healthy habits including personal cleanliness and hygiene.
(iii) Counselling and awareness regarding reproductive organs, safe and hygienic sexual practices will play an important role in making people reproductively healthy.

Reproductive health has improved in India, in terms of
(i) Reduced maternal and infant mortality rates.
(ii) Early detection and cure of STDs,
(iii) Assistance to infertile couples.
(iv) Availability of a variety of methods for family planning.
(v) Availability of maternal and child healthcare programmes.
(vi) Introduction of sex education in schools.

STDs can be prevented by
(i) Avoiding sex with unknown partner or multiple partners.
(ii) Avoid unprotected sexual intercourse, always use condoms.
(iii) Use sterilised needles and syringes.
(iv) In case of doubt, consult a doctor as early as possible for early detection and get completely treated if diagnosed with disease.

Special attention needs to be given to the following aspects
(i) Educating people (starting from age group above 12 years) about reproductive system, processes and practices and importance of safe and responsible sex.
(ii) Providing education about harmful sexual practices, unwanted pregnancy, unsafe abortion, reproductive tract infections and cancers, gender based responsibilities and gender equality in making decisions about sex, etc.
(iii) Establishing proper systems of education, counselling, prevention, detection and management of health problems, care and rehabilitation and ensuring easy accessibility of appropriate services.
(iv) Establishing appropriate systems to provide effective and accessible healthcare for women during pregnancy and childbirth to provide the best chance for a healthy mother.
(v) Making policies and practices for population growth control, so that people can have access to safe, effective and affordable contraception. But they should have the right to decide,when and which method to adopt.

Generic 5

4 x 5 = 20

Oogenesis is the production of egg cells inside the ovaries. During foetal development, few germinal cells in human ovary differentiate and divide mitotically to produce egg mother cell/oogonia. Further, oogonia become larger and divide to produce diploid primary oocyte. In follicular prenatal phase, the primary oocytes start first meiotic division but are transitionally suspended into prophase stage of meiosis I and are stored in the follicle. After puberty, primary oocyte resumes the division and completion of first meiotic division produce one secondary oocyte (egg cell) and one polar body (non-functional cell).

(a) sexually
(b) viviparous
(c) internal
(d) haploid
(e) diploid
(f) ovulation
(g) luteinising hormone
(h) syngamy
(i) ampullary-isthmic junction
(j) blastula
(k) umbilical cord.

(a) False
Androgens are formed by Leydig cells.
(b) True.
(c) False
Oogenesis takes place in the ovarian follicles.
(d) True
(e) False
Oogenesis occurs in the female embryo before birth but does not complete until puberty.
(f) True.
(g) True.

(a) Ovulation is preceded by proliferative/follicular phase and is followed by luteal/secretory phase.

(b) Role of Gonadotropins

The gonadotropin,follicle stimulating hormone (FSH) stimulates follicular development and secretion of estrogens by the growing follicles.

Both LH and FSH attain a peak level in the middle of the cycle.

Rapid secretion of luteinishing hormone (LH) during the mild-cycle (called LH surge) causes ovulation.

LH also stimulates the formation of corpus luteum from the ruptured follicle and secretion of progesterone from it.

Multiple Choice Question

21 x 1 = 21

10.