Tag: auxins and gibberellins

Questions Related to auxins and gibberellins

I. Assertion: The presence of apical bud inhibits the growth of lateral bud, this is called apical dominance.
II. Reason: Auxin is responsible for apical dominance.

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. I and II both are wrong

  2. I is wrong and II is correct

  3. I and II both are correct , II is correct explanation for I

  4. I and II both are correct , II is not a correct explanation for I

Show answer
Correct Option: C
Explanation:

Auxins when applied to plant cuttings help in formation of adventitious roots. Higher concentration of auxin at apical bud suppresses growth of lateral bud having low concentration of auxin.

Apical dominance is not affected by ...................

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Indole acetic acid

  2. Gibberellic acid

  3. Indole acetaldehyde

  4. Indole butyric acid

Show answer
Correct Option: B
Explanation:

GA promotes the elongation of plants by inducing the division of lateral meristem. Whereas, the phytohormone auxin causes the apical dominance in plants. In the given options all other options other than gibberellic acid accounts for different types of auxin.

A potted plant placed near the window bends outwardly due to 

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Greater oxygen availability to the tip.

  2. More auxin content on the shaded side.

  3. Greater light availability to tip.

  4. Availability of necessary warmth to the tip.

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Correct Option: B
Explanation:

Greater growth on the shaded side of the stem is due to more accumulation of auxin on the shaded  side than on the illuminates. Auxin causes bending of plant towards light. Phototropism is induced by auxin hormone.

Removal of apical bud makes the plant

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Bushy

  2. Grow rapidly

  3. Grow slowly

  4. Dormant

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Correct Option: A
Explanation:

Apical dominance is a phenomenon in which main stem grows faster than the lateral branches. Apical bud produces auxin hormone that promotes apical dominance and inhibits growth of the lateral buds. When the apical bud is removed, the source of auxin is removed. Due to this, the lateral buds grow faster and makes plant bushy. 

Thus, the correct answer is option A.

Apical dominance is caused by

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Abscisic acid in lateral bud

  2. Cytokinin in leaf tip

  3. Gibberellin in lateral buds

  4. Auxin in shoot tip

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Correct Option: D
Explanation:

Apical dominance is a phenomenon in which central stem is dominant and lateral stems are suppressed. It is due to plant hormones produced in the tip of the shoot. Auxin hormone is responsible for apical dominance and cytokinin hormone is responsible for breaking the apical dominance. 

Thus, the correct answer is option D.

The hormones responsible for apical dominance is

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. IAA

  2. GA

  3. ABA

  4. Florigen

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Correct Option: A
Explanation:

Apical dominance is a phenomenon in which central stem is dominant and lateral branches are suppressed. It is due to plant hormones produced in the tip of the shoot. IAA, a type of auxin hormone is responsible for apical dominance and cytokinin hormone is responsible for breaking the apical dominance. 

So, the correct answer is 'IAA'

Apical dominance as found in higher plants is due to

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Photoperiodism

  2. Phototropism

  3. Hormones

  4. Enzymes

Show answer
Correct Option: C
Explanation:

Apical dominance is a phenomenon in which central stem is dominant and lateral stems are suppressed. It is due to plant hormones produced in the tip of the shoot. Auxin hormone is responsible for apical dominance and cytokinin hormone is responsible for breaking the apical dominance. 

Thus, the correct answer is option C.

Removal of apical bud results in

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Formation of new apical bud

  2. Elongation of main stem

  3. Death of plant

  4. Formation of lateral branching

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Correct Option: D
Explanation:

Apical dominance is a phenomenon in which central stem is dominant and lateral stems are suppressed. It is due to plant hormones produced in the tip of the shoot. Auxin hormone is responsible for apical dominance. When apical bud is removed, there is growth of lateral bud. This results in formation of lateral branching. This makes plant bushy.

Thus, the correct answer is option D.

Lateral axillary buds are not allowed to grow by

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Auxin

  2. Ethylene

  3. Gibberellin

  4. Cytokinin

Show answer
Correct Option: A
Explanation:

Apical dominance is a phenomenon in which central stem is dominant and lateral stems are suppressed. It is due to plant hormones auxin produced in the tip of the shoot. It promotes apical dominance and does not allow lateral axillar buds to grow. However, when tip of the shoot is cut, it promotes the growth of lateral axillary buds.

So, the correct answer is 'Auxin'

Auxins promote

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Apical dominance

  2. Cambial activity

  3. Cell growth

  4. All the above

Show answer
Correct Option: A
Explanation:

Apical dominance is a phenomenon in which central stem is dominant and lateral stems are suppressed. It is due to plant hormone auxin produced in the tip of the shoot. Auxin hormone is responsible for apical dominance and cytokinin hormone is responsible for breaking the apical dominance. 

Thus, the correct answer is 'Apical dominance'.