Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

51.

Assertion: Maize is an albuminous seed. 

Reason: Endosperm is completely absorbed by its growing embryo

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


C.

If assertion is true but reason is false

Any seed which contains endosperm or perisperm at maturity is called albuminous or endospermic seed i.e., food reserve of the seed is stored in endosperm or perisperm, e.g. rubber, coconut, castor bean, maize and other cereals. Seed that does not have endosperm at maturity and in which cotyledons absorb food reserve from endosperm during development and act as storage organs is called exalbuminous or nonendospermic seed, e.g., mustard, groundnut, bean, pea etc.


52.

Assertion: Many plants are propagated vegetatively even though they bear seeds.

Reason: Potatoes multiply by tubers and apple by cutting.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


A.

If both assertion and reason are true and reason is the correct explanation of assertion

The most common form of asexual reproduction in plants is called vegetative propagation. It is the formation of new plants from vegetative units (propagules) such as buds, tubers, rhizomes, roots, stem, leaf etc. Besides the natural methods of vegetative propagation, there are a number of techniques for artificial vegetative propagation of economically and aesthetically important plants. Potatoes are produced by tubers and not by seeds. Stem tubers are found in potato and artichoke. They have buds in the region of nodes or eyes for vegetative multiplication. Root cuttings are used in propagation of lemon, apple, orange, blackberry etc.


53.

Assertion: Hybridoma cells are shifted to a medium deficient in nutrient which cannot be synthesized by myeloma cells.

Reason: This medium allows selection of hybridoma cells.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


A.

If both assertion and reason are true and reason is the correct explanation of assertion

The hybridoma cells are shifted to a medium deficient in nutrient which cannot be synthesized by myeloma cells so that myleoma cells could be removed or hybridoma cells could be purified. The unfused myleoma cells die while hybridoma cells survive. The hybridoma cells are allowed to multiply separately.


54.

Assertion: Nuclear endosperm is formed by subsequent nuclear division without wall formation.

Reason: Coconut is an example of such endosperm, where the endosperm remains nuclear throughout the development of the fruit

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


C.

If assertion is true but reason is false

In nuclear endosperm, first and further divisions of primary endosperm nucleus arc not followed by cytokinesis or wall formation and thus these free nuclear divisions lead to formation of a large number of free nuclei in embryo sac. At maturity, centripetal wall formation may occur to make the tissue partly cellular. Endosperm of coconut is unique in sense that it is both nuclear and cellular. Here the primary endosperm nucleus undergoes a number of free nuclear divisions. When the fruit is about 50 mm long the embryo sac remains filled with a watery fluid or milk containing free nuclei and fine cytoplasmic particles. At a later stage when the fruit becomes about 100mm in length the liquid shows in addition to free nuclei, several cells each enclosing variable number of nuclei. Thus coconut has multicellular endosperm (called coconut meat) in the outer part and free


55.

Assertion: Koel does not build nest for egg laying.

Reason: Koel lays its eggs in the nest of tailor bird.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is falsen

  • If both assertion and reason are false.


C.

If assertion is true but reason is falsen

Koel is a nest parasite and does not build a nest of its own. It simply lays its eggs in a crow's nest so that the eggs and young ones, are looked after by the foster parents


56.

Assertion: In mammals the female secondary sexual characters are developed by gonadotropins.

Reason: Gonadotropins are secreted by graafian follicle.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


D.

If both assertion and reason are false.

The female secondary sexual characters are developed by estrogens. Estrogens are steroid hormones secreted by growing ovarian follicles. It includes estradiol, estriol and estrone. This hormone is responsible for the development of female secondary sexual and accessory characters. In humans it is also formed in the adrenal cortex, testis and foetoplacental unit. Gonadotrophic hormones (LH and FSH) are secreted by the anterior lobe of pituitary gland. LH is responsible for ovulation and transforms graafian follicle into corpus luteum and FSH stimulates spermatogenesis and maturation of graafian follicle and secretion of estrogen in ovaries.


57.

The growth curve of bacterial population in lab is plotted against time. What will be the shape of graph

  • Sigmoid

  • Hyperbolic

  • Ascending straight line

  • Descending straight line


B.

Hyperbolic

Under continuous supply of food and spacein the laboratory conditions the bacterial population grows exponentially and shows a Jshaped curve, thus the curve would be hyperbolic.

Such populations ultimately crash when the population size grows beyond carrying capacity.


58.

Assertion: The plant biomass which serves as the food of herbivores and decomposers is said to result from the gross primary productivity.

Reason: Gross primary productivity is the rate of net production of organic material (biomass).

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


D.

If both assertion and reason are false

Net primary productivity is the available biomass for the consumption to heterotrophs (herbivores and decomposers). The rate of biomass production is called productivity. It has two aspects, gross primary productivity and net primary productivity. The rate of total production of organic matter during photosynthesis is known as gross primary productivity. Its considerable amount is utilised by plants in respiration. The organic matter synthesised by plants (GPP) minus the rate of respiration and other loss represents the net primary productivity


59.

Assertion: Dimethyl mercury is a highly persistent pollutant that accumulates in food chains.

Reason: Mercury pollution is responsible for minamata.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


B.

If both assertion and reason are true but reason is not the correct explanation of assertion

Mercury is an important toxic pollutant It is changed to water soluble dimethyl mercury which undergoes biomagnification, i.e., accumulates in the body oforganisms inhabiting in the water. Eating poisoned animals causes deformity known as minamata disease which is characterized by diarrhoea, impairment of various senses, numbness of lips, blurring of visior, mental dearrangement and death.


60.

Assertion: Persons suffering from haemophilia fail to produce blood clotting factor VIII.

Reason: Prothrombin producing platelets in such persons are found in very low concentration.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


C.

If assertion is true but reason is false

Haemophilia, also called bleeder's disease is a X-linked recessive disorder. The person which contains the recessive gene for haemophilia lacks a normal clotting substance (thromboplastin) in blood. So minor injuries cause continuous bleeding and ultimate death of the person due to hemorrhages.

Haemophilia is of two types : type A characterized by lack of antihaemophilic globulin (factor VIII) and type B characterized by a defect in plasma thromboplastic component (factor IX).
Prothrombin is an inactive plasma protein and is produced by liver. It helps in blood clotting. It is not produced by platelets.