Biology

Plant Growth and Hormones

695 Questions

Plant growth and hormones is a vital topic in biology that covers the physiological effects of different plant regulators like auxins, gibberellins, and cytokinins. These concepts are frequently tested in various general science sections of competitive exams. Practicing these questions helps clarify complex mechanisms like vernalisation, senescence, and tropism for test takers.

Abscisic acid effectsCytokinin functionsAuxins and tropismPlant tissue cultureSenescence in plantsNatural plant hormones

Plant Growth and Hormones Questions

Multiple choice biology food and human health balanced diet and malnutrition balanced and unbalanced food digestive disorders diseases caused by changes in lifestyle diseases and toxic substance health and its maintenance

Richmond-Lang effect is 

  1. The effect of kinetins in delaying senescence

  2. The effect of colines on root and shoot formation

  3. The effect of traumatic acid in wound formation

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cytokinins delay the senescence of leaves and other organs by controlling protein synthesis and mobilization. Reported by "Richmond and Lang" in 1957 working on "Xanthium leaves".

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

Which growth hormone is associated with stomatal movements?

  1. Auxin

  2. ABA

  3. Gibberellin

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

ABA is known to have a direct effect on the movement of stomata. When ABA is present, it does not allow the uptake of potassium ions which help in the opening of stomata and hence the pore closes.

Effect of ABA is countered by hormones Auxin and Cytokinin.
Gibberellins have a major contribution to cell elongation and growth.
So the correct answer is 'ABA'. 

Multiple choice biology anatomy of flowering plants theories of meristematic cell development theories of shoot apical meristem development shoot and root apex

The shoot branching depends upon the development of axillary buds, but many of the buds in axillary position never grow out due to the _____________________.

  1. Inhibitory factor present in the axillary bud

  2. Inhibitory factor present in the apical bud

  3. Interaction of factors present in both the axillary & apical bud

  4. Ibhibition under genetic control
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice biology chemical coordination in plants ethylene plant hormones plants and animal hormones

The most efficient precursor of ethylene is ................

  1. Adenine

  2. Thiocarbarnate

  3. Zeatin

  4. Methionine
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Ethylene is a plant hormone which is present in gaseous form. It is formed by the breakdown of methionine, which is in all cells. Thus, methionine is called as the precursor of ethylene hormone. Ethylene hormones helps in the ripening of fruits when sprayed onto it. Ethylene hormone is present mainly in rapidly dividing cells, which is usually in darkness due to the action of methionine, which is the precursor molecule.

Multiple choice biology chemical coordination in plants ethylene plant hormones plants and animal hormones

Which one of the following is a gaseous plant hormone?

  1. Auxin

  2. Gibberellin

  3. Ethylene

  4. Cytokinin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ethylene is a simple gaseous plant growth regulator (PGR). It is synthesised in large amounts by tissues undergoing senescence and ripening fruits. Influences of ethylene on plants include horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot seedlings. Ethylene promotes senescence and abscission of plant organs especially of leaves and flowers. Ethylene is highly effective in fruit ripening. It enhances the respiration rate during ripening of the fruits. This rise in rate of respiration is called as respiratory climactic.

Thus, the correct answer is option C.

Multiple choice biology chemical coordination in plants ethylene plant hormones plants and animal hormones

A natural growth regulator is 

  1. Ethylene

  2. NAA

  3. 2, 4-D

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

Ethylene is a simple gaseous plant growth regulator. It is synthesised in large amounts by tissues undergoing senescence and ripening fruits. Influences of ethylene on plants include horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot seedlings. Ethylene promotes senescence and abscission of plant organs especially of leaves and flowers. Ethylene is highly effective in fruit ripening. It enhances the respiration rate during ripening of the fruits. This rise in rate of respiration is called as respiratory climactic.

Thus, the correct answer is option A.

Multiple choice biology chemical coordination in plants ethylene plant hormones plants and animal hormones

Among the following which helps in early ripening of fruits?

  1. Methane

  2. Ethylene
  3. CO$ _{2}$

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

Ethylene is a simple gaseous plant growth regulator. It is synthesised in large amounts by tissues undergoing senescence and ripening fruits. Influences of ethylene on plants include horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot seedlings. Ethylene promotes senescence and abscission of plant organs especially of leaves and flowers. Ethylene is highly effective in fruit ripening. It enhances the respiration rate during ripening of the fruits. This rise in rate of respiration is called as respiratory climactic.

Thus, the correct answer is option B.

Multiple choice biology chemical coordination in plants ethylene plant hormones plants and animal hormones

Ethylene is used for 

  1. Decrease the senescence

  2. Increase the height of stem

  3. Ripening of fruits

  4. Prevention of leaf fall
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ethylene is a simple gaseous plant growth regulator (PGR). It is synthesised in large amounts by tissues undergoing senescence and ripening fruits. Influences of ethylene on plants include horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot seedlings. Ethylene promotes senescence and abscission of plant organs especially of leaves and flowers. Ethylene is highly effective in fruit ripening. It enhances the respiration rate during ripening of the fruits. This rise in rate of respiration is called as respiratory climacteric.

Thus, the correct answer is option C.

Multiple choice biology chemical coordination in plants ethylene plant hormones plants and animal hormones

Which of the following is used for ripening of fruits?

  1. Auxin

  2. Abscisic acid

  3. Ethylene gas

  4. Cytokinin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ethylene is a simple gaseous plant growth regulator (PGR). It is synthesised in large amounts by tissues undergoing senescence and ripening fruits. Influences of ethylene on plants include horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot seedlings. Ethylene promotes senescence and abscission of plant organs especially of leaves and flowers. Ethylene is highly effective in fruit ripening. It enhances the respiration rate during ripening of the fruits. This rise in rate of respiration is called as respiratory climactic.

Thus, the correct answer is option C.

Multiple choice biology chemical coordination in plants ethylene plant hormones plants and animal hormones

Which plant hormone causes fruit ripening?

  1. Indole acetic acid

  2. Cytokinin

  3. Ethylene

  4. Gibberellic acid
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During the early 20th century, scientists observed that the gas ethylene (C$ _2$H$ _4$) has several effects on plant growth, but not until 1934 did they demonstrate that plants produce ethylene. This natural hormone influences many plant processes. Ethylene inhibits cell elongation, promotes seed germination, promotes apical dominance and is involved in plant responses to wounding or invasion by disease causing microorganisms. Ethylene also has a major role in many aspects of senescence, including fruit ripening. As a fruit ripens, it produces ethylene, which triggers an acceleration of the ripening process. This induces the fruit to produce more ethylene, which further accelerates ripening.

Thus, the correct answer is option C.

Multiple choice biology chemical coordination in plants ethylene plant hormones plants and animal hormones

Fruit ripening can be hastened by treatment with 

  1. Indole acetic acid

  2. Florigen

  3. Ethylene

  4. Cytokinin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ethylene is a simple gaseous plant growth regulator (PGR). It is synthesised in large amounts by tissues undergoing senescence and ripening fruits. Influences of ethylene on plants include horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot seedlings. Ethylene promotes senescence and abscission of plant organs especially of leaves and flowers. Ethylene is highly effective in fruit ripening. It enhances the respiration rate during ripening of the fruits. This rise in rate of respiration is called as respiratory climacteric.

Thus, the correct answer is option C.