Tag: plant growth and development

Quizzes (13) Questions (188)

Questions Related to plant growth and development

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

How does pruning help in making the hedge dense?

  1. It releases wound hormones.

  2. It induces the differentiation of new shoots from the rootstock.

  3. It frees auxillary buds from apical dominance.

  4. The apical shoot grows faster after pruning.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Auxin is the phytohormone which is responsible for promoting apical dominance in plants. Auxin is usually seen at the growing tips of plants. Thus the auxin present at the tip of plants will be channelized sidewards, lateral meristem; so that the plants will not grow tall but instead becomes bushy in nature.

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

Which of the following is responsible for apical dominance ?

  1. GA$ _3$

  2. IAA

  3. ABA

  4. Florigen
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Auxins promote elongation of stem and coleoptile. It promotes the growth by the elongation of cells in the apical meristem. Growth in the lateral bud is inhibited when the apical bud of a tall plant remains intact. However, the lateral bud grows rapidly on the removal of apical bud. Suppression of growth in the lateral bud by apical bud due to auxin produced by apical bud is termed as apical dominance. IAA is an example of auxin. 

Thus, the correct answer is option B. 

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

Which hormone is responsible for apical growth?

  1. IAA

  2. ABA

  3. GA

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Auxins (like IAA) and gibberellins (GA) are growth promoting phytohormones. IAA promotes apical growth whereas GA causes internodal elongation. Promotion of apical growth by auxins and suppression of axillary growth is also called as apical dominance.

Thus, the correct answer is option A.

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

Apical dominance is not affected by

  1. Indole acetic acid

  2. Gibberellin

  3. Indoleacetaldehyde

  4. Indole-3-butyric acid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Apical dominance is a physiological response of auxins. The chemicals mentioned in options A, C and D are all auxins. They inhibit the growth of axillary buds and stimulate the growth of apical bud. This phenomenon is called as apical dominance. Gibberellins are also growth promoting phytohormones. They stimulate internodal elongation. Thus, bringing about an increase in length or height of plants.

Thus, the correct answer is option B.

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

Who demonstrated that cut tip of canary grass seedlings resume phototropic sensitiveness when pasted back in its position?

  1. Charles Darwin

  2. F W Went

  3. Boysen Jensen

  4. Paal
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Charles Darwin used cut tip of canary grass seedlings to demonstrate the sensitivities of the stem apex to light mediated movements. 

Boysen used Avena cut tips to demonstrate presence of plant hormones. 
Paal showed through his experiments that some other growth promoting substances are present in cut tips. 
Hence, option A is correct. 

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

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.

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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

  1. Indole acetic acid

  2. Gibberellic acid

  3. Indole acetaldehyde

  4. Indole butyric acid
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

A potted plant placed near the window bends outwardly due to 

  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.
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Removal of apical bud makes the plant

  1. Bushy

  2. Grow rapidly

  3. Grow slowly

  4. Dormant
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

Apical dominance is caused by

  1. Abscisic acid in lateral bud

  2. Cytokinin in leaf tip

  3. Gibberellin in lateral buds

  4. Auxin in shoot tip
Reveal answer Fill a bubble to check yourself
D Correct answer
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.