Question Set A

cbse 12th Standard Biology Sexual Reproduction in Flowering Plants Model Questions Papers Study Material - QB365

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Questions:

Assertion and reason

30 x 1 = 30

Assertion (A): Decidua is expelled after the birth of the baby.
Reason (R): Foetal blood and maternal blood in human Placenta are separated by only blood capillaries.
Codes:
a) Both (A) and (R) are true and (R) is the correct explanation of (A)
b) Both (A) and (R) are true and (R) is not the correct explanation of (A)
c) (A) is true but (R) is false
d) Both (A) and (R) are false

Assertion (A): Corpus luteum degenerated if the ovum remains unfertilized.
Reason (R): Corpus luteum secretes progesterone which maintains the pregnancy.
Codes:
a) Both (A) and (R) are true and (R) is the correct explanation of (A)
b) Both (A) and (R) are true and (R) is not the correct explanation of (A)
c) (A) is true but (R) is false
d) Both (A) and (R) are false

Assertion (A): The vagina is covered by 'hymen' a membrane completely until the first coitus.
Reason (R): The ovulation starts only after the first coitus.
Codes:
a) Both (A) and (R) are true and (R) is the correct explanation of (A)
b) Both (A) and (R) are true and (R) is not the correct explanation of (A)
c) (A) is true but (R) is false
d) Both (A) and (R) are false

Assertion (A): 'Cryptorchidism' may leads to sterility in males.
Reason (R): For spermatogenesis,2-2.5°C lower temperature than the normal internal body temperature is required.
Codes:
a) Both (A) and (R) are true and (R) is the correct explanation of (A)
b) Both (A) and (R) are true and (R) is not the correct explanation of (A)
c) (A) is true but (R) is false
d) Both (A) and (R) are false

Assertion (A): A drop in temperature does not affect spermatogenesis.
Reason (R): During temperature drops the smooth muscles contract and bring the testes closer to the pelvic cavity.
Codes:
A) Both (A) and (R) are truc and (R) is the correct explanation of (A)
B) Both (A) and (R) are true and (R) is not the correct explanation of (A)
C) (A) is true but (R) is false
D) (A) is false but (R) is true

Assertion (A) : Pollen grains of Zostera can floatbelow the surface of water.
Reason (R):They have same specific gravityas that of water.
Codes:
A) Both (A)and (R)are true and (R) is the correct explanation of (A)
B) Both (A) and (R) are true and (R) is not the correct explanation of (A)
C) (A)is true but.(R) is false
D) Both (A) and (R) are false

Assertion (A) : Coconut endosperm is bothcellular and nuclear type.
Reason (R) : Development is first cellular andthen free nuclear type.
Codes:
A) Both (A)and (R)are true and (R) is the correct explanation of (A)
B) Both (A) and (R) are true and (R) is not the correct explanation of (A)
C) (A)is true but.(R) is false
D) Both (A) and (R) are false

Assertion: Rapid decline in death rate, MMR and IMR have lead to a staggering rise in population.
Reason: Such an alarming growth rate has lead to an absolute scarcity of even the most basic requirements, i.e. food and shelter.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Assertion: In the testis, spermatogenesis occurs in the seminiferous tubules and testosterone secretion takes place from the sertoli cells.
Reason: Testosterone brings growth and maturation of primany sex organs and also development of accessory sex characters.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

10.

Assertion: Amniocentesis is often missemployed.
Reason: Amniocentesis is meant for determining the genetic disorders in the foetus, but it is being used to determine the sex of the foetus, leading to death of the normal female foetus.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

11.

Assertion: Family planning is an action plan to attain reproductive health among people.
Reason: Improved programmes covering reproduction related areas were propagated by RCH to create awareness among people.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

12.

Assertion: Although geitonogamy is functionally cross-pollination involving a pollinating agent, genetically it is similar to autogamy since the pollen grains come from the same parent.
Reason: In getionogamy, pollen grains from the anthers of one flower are transferred to the stigma of another flower borne on the same plant.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

13.

Assertion: Exine of a pollen grain is made up of sporopollenins which are resistant to high temperatures, strong acids or alkali as well as enzymatic degradation.
Reason: Sporopollenins are absent in the region of germ pores.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

14.

Assertion (A) : Embryo sac development is monosporic in Polygonum.
Reason (R) : In this development, only one functional megaspore is present at chalazal end.
(a) If both A and R are true and R is correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

15.

Assertion (A) : Some plants shed pollen at the 3-celled condition.
Reason (R) : These plants carry 3 male gametes since the beginning of reproductive process.
(a) If both A and R are true and R is correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

16.

The diagram given below shows the event of cleavage. Refer to the diagram and comment upon the appropriateness of assertion and Reason.

Assertion (A) : During cleavage, the cells divide and continue to rise in number, but the mass of protoplasm remains same.
Reason (R) : With each consecutive subdivision there is approximately half the cytoplasm in each daughter cell.
(a) If both A and R are true and R is the correct explanation of the A
(b) If both A and R are true, but R is not the correct explanation of the A
(c) If A is true, but R is false
(d) If A is false, but R is true

17.

Assertion (A) Very often persons suffering from Sexually Transmitted Diseases (STDs) do not go for timely detection and proper treatment.
Reason (R) Absence or less significant symptoms in the early stages of STDS and the social stigma attached to the disease
(a) If both A and R are true andRis the correct explanation of the A
(b) If both A and R are true, but R is not the correct explanation of the A
(c) If A is true, but R is false
(d) If A is false, but R is true

18.

Assertion (A) Vasectomy is a sterilisation procedure advised for females as a terminal method.
Reason (R) In vasectomy, a small part of the vas deferens is remnoved or tied by blocking gamete transport therefore preventing conception.
(a) If both A and R are true and R is the correct explanation of the A
(b) If both A and R are true, but R is not the correct explanation of the A
(c) If A is true, but R is false
(d) If A is false, but R is true

19.

Assertion (A)Contraceptives are methods to prevent unwanted pregnancies.
Reason (R) Unwanted pregnancies can only be prevented by using oral contraceptives
(a) If both A and R are true and R is the correct explanation of the A
(b) If both A and R are true, but R is not the correct explanation of the A
(c) If A is true, but R is false
(d) If A is false, but R is true

20.

Assertion : Enterobiasis is a sexually transmitted disease caused by pinworm.
Reason : Enterobiasis is treated with antihelminthic drugs.
Codes :
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false.

21.

Assertion : Subcutaneous implants (Norplants) involve implantation of synthetic progesterone under the skin. ,
Reason : Norplants block ovulation and thickens the cervical mucus to prevent sperm transport.
Codes :
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false.

22.

Assertion : PCR, ELISA, DNA hybridisation are confirmatory tests for sexually transmitted diseases.
Reason : Incidence of STDs are very high in persons above the age of 30.
Codes :
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false.

23.

Assertion : A medical termination of pregnancy is legally allowed upto the 28th week of pregnancy.
Reason : MTP is done if family physician or gynaecologist consider the need for abortion.
Codes :
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false.

24.

Assertion: All copulations do not lead to the fertilisation and pregnancy.
Reason : Fertilisation can occur only if the ovum and sperms are transported simultaneously to the ampullary - isthmic junction.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true butreason is false.
(d) Both assertion and reason are false.

25.

Assertion: In blastulation, cell masses show morphogenetic movements.
Reason: A three layered blastocyst is formed during blastulation.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true butreason is false.
(d) Both assertion and reason are false.

26.

Assertion: The second meiotic division of the developing ovarian follicles is completed just after conception.
Reason: Conception is the onset of pregnancy when the implantation of blastocyst take place
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true butreason is false.
(d) Both assertion and reason are false.

27.

Assertion: Ubisch bodies are produced by glandular tapetum.
Reason: Ubisch bodies participated in the thickening of exine
Codes:
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false

28.

Assertion: Allogamy includes both geitonogamy and xenogamy.
Reason: Allogamy needs abiotic or biotic external agencies for pollination
Codes:
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false

29.

Assertion: Placenta is tissue present inside the ovary.
Reason: Placenta bears ovules
Codes:
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false

30.

Assertion: One pollen mother cell forms four microspores.
Reason: Microspores are formed due to reduction division
Codes :
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false

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Answers Key:

Assertion and reason

30 x 1 = 30

c) (A) is true but (R) is false

b) Both (A) and (R) are true and (R) is not the correct explanation of (A)

d) Both (A) and (R) are false

a) Both (A) and (R) are true and (R) is the correct explanation of (A)

A) Both (A) and (R) are truc and (R) is the correct explanation of (A)

A) Both (A)and (R)are true and (R) is the correct explanation of (A)

C) (A)is true but.(R) is false

(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
Explanation:
There is rapid decline in Infant Mortality Rate (IMR) and Maternal Mortality Rate (MMR) The recent World Bank data puts the MMR for India reported in 2015 at 174 per 100, 000 live births, which is a significant decline from the 215 figure that was reported in 2010.

(d) If both Assertion and Reason are false.
Explanation:
In the testis, spermatogenesis occurs in the seminiferous tubules and testosterone secretion takes place in the interstitial cells. Testosterone brings growth and maturation of secondary sex organs. It also brings about development of secondary sex characters.

10.

(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation:
Amniocentesis (amniotic fluid test or AFT) is a medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections, and also for sex determination, in which a small amount of amniotic fluid, which contains foetal tissues, is sampled from the amniotic sac surrounding a developing foetus, and then the foetal DNA is examined for genetic abnormalities.

11.

(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
Explanation:
Family planning helps in maintaining reproductive health.

12.

(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation:
Geitonogamy is a type of pollination in which pollen grains of one flower are transferred to the stigma of another flower belonging to either the same plant or genetically similar plant. It usually occurs in plants which show monoecious condition (unisexual male and female flowers borne on the same plant. Thus, geitonogamy is functionally cross pollination as it involves pollinating agent to carry out pollination, but genetically it is similar to autogamy (self-pollination) since the pollen grains come from the genetically same plant.

13.

(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
Explanation:
Wall of a pollen grain consists of two layers– outer exine and inner intine. Exine is the hard outer layer which is made up of sporopollenin. Sporopollenin is one of the most resistant organic material known. It can withstand high temperature, strong acids or alkali and is not degraded by enzymes. Because of the presence of sporopollenin, pollen grains are well preserved as fossils. At certain places, the exine is thin or absent, these areas may have thickened intine or deposition of callose. They are called germ pores (if rounded) or germinal furrows (if elongated). Sporopollenin is absent in the region of germ pores or germinal furrows.

14.

(a) If both A and R are true and R is correct explanation of A

15.

16.

(b) If both A and R are true, but R is not the correct explanation of the A

17.

(a) If both A and R are true and R is the correct explanation of the A

18.

(d) If A is false, but R is true

19.

20.

(b) Both assertion and reason are true but reason is not the correct explanation of assertion.

21.

(b) Both assertion and reason are true but reason is not the correct explanation of assertion.

22.

(c) : STDs are a major threat to healthy society. Incidence of STDs is very high in persons who have 15-24 years of age.

23.

(b) Both assertion and reason are true but reason is not the correct explanation of assertion.

24.

(a): Fertilisation can only occur if the ovum and sperms are transported simultaneously to the ampullary-isthmic junction and ovum is released only once a month. This is one of the reasons why all copulations do not lead to fertilisation and pregnancy.

25.

(d): In blastulation cells do not move. A single layered hollow blastocyst is formed.

26.

(b) Both assertion and reason are true but reason is not the correct explanation of assertion.

27.

(b) The Ubisch bodies are produced only by the glandular tapetum. Ubisch bodies get covered with sporopollenin and thus increase thickening of exine. The Ubisch bodies are involved in the external thickening of the exine, whose pattern is laid down by the spore cytoplasm in the tetrad stage.

28.

(b) Cross pollination is the transfer of pollen grains from the anther of one flower to the stigma of another flower, i.e., allogamy. Cross pollination is further classified depending on whether the pollination has occurred between two flowers on the same plant (geitonogamy) or between two flowers on different plants (xenogamy). Cross pollination (allogamy) is performed with the help of an external agency. The latter may be abiotic (e.g., wind, water) or biotic (e.g., insects, birds, bats, snails).

29.

(b) Placenta is a ridge of tissue in the inner wall of the ovary bearing one or more ovules and the manner of distribution of the placenta within the ovary is called placentation

30.

(a) The sporogenous cells of anther may directly function as microspore mother cells (also called pollen mother cells or PMCs) or they may undergo a few mitosis to add up to their number before entering meiosis. Each PMC, by a meiotic division, gives rise to a group of four haploid microspores. The aggregates of four microspores are referred to as microspore tetrads.