Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

71.

Which one of the following may require pollinators, but is genetically similar to autogamy?

  • Geitonogamy

  • Xenogamy

  • Apogamy

  • Apogamy


A.

Geitonogamy

Geitonogamy is functionally cross pollination but genetically it is autogamy because in geitonogamy the pollens come from the same plant. Pollens are being transferred to the stigma of one flower to another flower of /on the same plant, which is genetically same. Therefore, geitonogamy is a cross pollination phenomenon but is equivalent to autogamy genetically. 

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72.

Which one of the following statements is correct with respect to immunity?

  • Preformed antibodies need to the injected to treat the bite by a viper snake

  • The antibodies against small pox pathogen are produced by T-lymphocytes

  • Antibodies are protein molecules, each of which has four light chains

  • Antibodies are protein molecules, each of which has four light chains


B.

The antibodies against small pox pathogen are produced by T-lymphocytes

In artificially acquired passive immunity performed antibody in an immune serum is introduced into the body by infection. As the antivenum used to treat snake bites. In this case, the body does not produce any antibodies. Antibody is a protein molecule having two light chain and two heavy chain. B-cells recognize and bind antigens and may differentiate to memory cell or plasma cells (produce antibody). T-cells casues transplant rejection. 

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73.

Which one of the following statements is not true?

  • Pollen grains are rich in nutrients, and they are used in the form of tablets and syrups

  • Pollen grains of some plants cause severe allergies and bronchial afflictions in some people

  • The flowers pollinated by flies and bats secrete foul odour to attract them

  • The flowers pollinated by flies and bats secrete foul odour to attract them


D.

The flowers pollinated by flies and bats secrete foul odour to attract them

Honey is made by bees by nectar and pollens. Bees collect pollen and nectar in the spring when most flowers and plants are in bloom. They collect them in their stomach about an hour,  the nectar mixes with the proteins and enzymes produced by bees, which convert nectar into honey.

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74.

Which one of the following represents a palindromic sequence in DNA?

  • 5´ - GATACC - 3´
    3´ - CCTAAG - 5

  • 5´ - GAATTC - 3
    3´ - CTTAAG - 5´

  • 5´- CCAATG - 3´
    3´ - GAATCC - 5´

  • 5´- CCAATG - 3´
    3´ - GAATCC - 5´


B.

5´ - GAATTC - 3
3´ - CTTAAG - 5´

In a palindrome, the base sequence in the second half of a DNA strand is the mirror image of sequence in first half. But in palindrome with rotational symmetry the base sequence in first half of one strand is mirror image of second half of complementary strand, e.g., 
5´ - GATACC - 3´
3´ - CCTAAG - 5´

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75.

Male gametes are flagellated in

  • Polysiphonia

  • Anabaena

  • Ectocarpus

  • Ectocarpus


C.

Ectocarpus

Male gametes are flagellated in Ectocarpus belonging to Phaeophyceae. The flagella of male and gamete plays an important role in establishing initial sexual contact with the female gamete. However, in Ectocarpus the female gamete too is flagellated but is different in structure. 
In Polysiphonia (Rhodophyceae) flagellated gametes are not observed, in Anabaena sexual reproduction through gametes is absent while in Spirogya sexual reproduction takes place by conjugation wherein male gamete passes through a tube to the adjacent filament. The male gametes here are non-flagellated and show amoeboid movement. 

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76.

The first clinical gene therapy was given for treating

  • diabetes mellitus

  • chicken pox

  • rheumatoid arthritis 

  • rheumatoid arthritis 


D.

rheumatoid arthritis 

Gene therapy is the treatment of disease by the transfer and extension of genetic material in the patient's cell in order to restore normal cellular functions. The first clinical gene therapy was given for treating adenosine deaminase deficiency.

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77.

The figure below shows three steps (A, B, C) of Polymerase Chain Reaction (PCR). Select the option giving correct identification together with what it represents?

  • B – Denaturation at a temperature of about 98°C separatiing the two DNA strands

  • A – Denaturation at a temperature of about 50°C

  • C – Extension in the presence of heat stable DNA polymerase

  • C – Extension in the presence of heat stable DNA polymerase


C.

C – Extension in the presence of heat stable DNA polymerase

There are three steps in polymerase chain reaction namely.
(i) Denaturation- at 94 degree straight C for DNA strand separation.
(ii) Annealing - binding of primer.
(iii) Extension in presence of DNA polymerase which is heat stable.

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