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 Multiple Choice QuestionsMultiple Choice Questions

1.

During seed germination its stored food is mobilised by

  • ethylene

  • cytokinin

  • ABA

  • gibberellin


D.

gibberellin

Gibberellin induces aleurone cells to secrete an enzyme to break stored food in the seed. Cytokinines promote nutrient mobilisation, which helps in the delay of leaf senescence. 
ABA plays an important role in seed development, maturation and dormancy. Ethylene induces fruit ripening, breaks seed dormancy.

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2.

Auxin can be bioassayed by

  • Avena coleoptile curvature

  • Hydroponics

  • Potometer

  • Lettuce hypocotyl elongation


A.

Avena coleoptile curvature

Auxin is a phytohormone that is often bioassayed by Avena coleoptile curvature test. The angle of curvature of a decapitated oat coleoptile is measured after placing an agar block containing auxin on one side. The ability of auxin to stimulate shoot growth is then measured.

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3.

Which one of the following growth regulators is known as stress hormone?

  • abscsic acid

  • Ethylene

  • GA3

  • Indole acetic acid


A.

abscsic acid

Abscisic Acid (ABA) is also known as stress hormone or dormin because  it is produced in much higher amounts, when plants are subjected to various kinds of stresses. It often gives plants organs a signal that they are undergoing physiological stresses such as lack of water, saline soil, cold temperature and frost. ABA often cause responses that help plants and protect against these stresses.

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4.

What causes a green plant exposed to the light on only one side, to bend toward the source of light as it grows?

  • Green plants need light to perform photosynthesis.

  • Green plants seek light because they are phototropic

  • Light stimulates plant cells on the lighted side to grow faster

  • Auxin accumulates on the shaded side, stimulating greater cell elongation there


D.

Auxin accumulates on the shaded side, stimulating greater cell elongation there

When a green plant exposed to light (phototropism) on one side, which make it bend towards the source of light is due to the effect of auxins. Auxin accumulates on the shaded side due to which it stimulates cell elongation and enlargement. Its movement is polar and passes from shoot tip to region of elongation. It helps in elongation of both roots and shoots. Auxin(indole 3-acetic acid) also produces tropical responses like phototropism and geotropism.

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5.

Through their effect on plant growth regulators, what do the temperature and light control in the plants?

  • Apical dominance

  • Flowering

  • Closure of stomata

  • Fruit elongation


B.

Flowering

There are three factors which govern the flowering in angiosperms. These factors are completion of juvenile phase and attaintment of mature or adult phase, suitable light and proper temperature. 

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6.

Which one of the following generally acts as an antagonist to gibberellins?

  • Zeatin

  • Ethylene

  • ABA

  • IAA


C.

ABA

Abscisic acid (ABA) is also called stress hormone. It is a mildly acidic growth hormone which functions as a general growth inhibitor by counteracting other hormones (auxin, gibberellin, cytokinin) or reactions mediated by them. It causes stomatal closure, abscission of flower and fruits while gibberellin helps in opening of stomata and promote development of fruits. 

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7.

The Avena curvature is used for bioassay of

  • GA3

  • IAA

  • Ethylene

  • ABA


B.

IAA

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8.

A few normal seedlings of tomato were kept in a dark room. After a few days they were found to have become white - coloured like albinos. Which of the following terms will you use to describe them?

  • Mutated

  • Embolised

  • Etiolated

  • Defoliated


C.

Etiolated

Etiolation is a process in which flowering plants are grown in the parital or complete absence of light. Etiolation is mainly characterised by long and weak steam and smaller, sparse pale yellow colour (chlorosis) leaves due to longer internodes.

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9.

Vernalisation stimulates flowering in

  • Zamikand

  • Turmeric

  • Carrot

  • Ginger


C.

Carrot

Vernalization is a process of shortening of juvenile or vegetative phase and hastening flowering by a previous cold treatment. Example - henbane, carrot, cabbage.

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10.

Match the following and select the correct answer.

Column I

Column  II

A.

Centriole

1.

Infolding in mitochondria

B.

Chlorophyll

2.

Thylakoids

C.

Cristae

3.

Nucleic acid

D.

Ribozymes

4.

Basal body cilia of flagella

  • A

    B

    C

    D

    4

    3

    1

    2

  • A

    B

    C

    D

    1

    2

    4

    3

  • A

    B

    C

    D

    1

    3

    2

    4

  • A

    B

    C

    D

    4

    3

    1

    2


A.

A

B

C

D

4

3

1

2

a) Centriole: In an organism with flagella and cilia, the position of these organelles is determined by the mother centriole which becomes the basal body.

b) Chlorophyll: Chlorophyll molecules are specially arranged in and around photosystem that is embedded in the thylakoid membrane of the chloroplast.

c) Cristae: These are folded in the inner membrane of mitochondria, which provides a large amount of surface area for chemical reaction.

d) Ribozymes (Ribonucleic acid enzymes) is an RNA molecule that is capable of catalysing the specific biochemical reaction of nucleic acids.

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