Biology

Plant Growth and Hormones

727 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 botany reproduction in angiospermic plants artificial vegetative propagation common modes of vegetative propagation vegetative propagation asexual modes of reproduction

A plant hormone that induces morphogenesis in plant tissue culture is

  1. Abscisic acid

  2. Gibberellin

  3. Cytokinin

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

Cytokinin is a plant hormone which is involved in various physiological processes. It promotes growth of shoot buds. It also induces cell division and shoot and root morphogenesis. In plant tissue culture, it is applied externally to induce morphogenesis

Thus, the correct answer is option C.

Multiple choice botany tissue culture common modes of vegetative propagation plant breeding for food production plant tissue culture

Callus is

  1. Plant hormone

  2. Root formation in culture media

  3. Plant by-product

  4. Undifferentiated mass of tissue
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Callus is a growing mass of unorganized plant parenchyma cells. It is mainly  used in plant tissue culture. So basically in other words, callus is a undifferentiated mass of tissue. 

Multiple choice botany tissue culture common modes of vegetative propagation plant breeding for food production plant tissue culture

Which increase shoot growth in callus culture?

  1. Cytokinin

  2. Auxin

  3. Gibberellin

  4. ABA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • The callus is an unspecialized, unorganized, growing and dividing the mass of cells.
  • It produced when explants are cultured on the appropriate solid medium, with both auxin and cytokinin in correct conditions.
  • In Callus culture, Auxins increase root growth and cytokinins increase shoot growth.
  • Hence Cytokinin increase shoot growth in callus culture.
  • So, the correct answer is 'Cytokinin'.
Multiple choice evs identifying the plants absorption of water from the soil root system the root system

Plants sense gravity with the help of

  1. Phytochromes

  2. Statoliths

  3. Phytohormones

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

In the root cap there is a special subset of cells, called as statocytes. Inside the statocyst cells, some specialized amyloplasts are involved in the perception of gravity by the plant (gravitropism). Statoliths settle at the bottom part of their cells and allow plants to sense gravity. Statoliths are also found in the endodermal layer of the inflorescence stem. The redistribution of auxin causes the shoot to turn in a direction opposite that of the gravity stimuli.

So, the correct answer is 'Statoliths'.

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

Hormone involved in phototropism is ____________.

  1. IAA

  2. gibberellin

  3. kinetin

  4. 2, 4-D.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Phototropic curvature is the result of uneven distribution of auxin. Darwin and Darwin observed that the coleoptiles of canary grass responded w unilateral illumination by growing towards the light source (phototropism). After a series of experiments, It was concluded that the tip of coleoptile contains auxin that caused the bending of the entire coleoptile in relation to the direction of light.

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

Which plant hormone induces the phenomenon of phototropism in plants?

  1. Auxins

  2. Ethylene

  3. Cytokinin

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

Auxins induce phototropism in plants, that growth of a plant part towards light (shoot) or away from light (root). 

Auxins bring about elongation and growth of the shoot towards light, being sensitive to light accumulate in the region opposite to the direction in which growth has to take place, here it brings about elongation of the cells and growth of the shoot in the direction of light.
So, the correct answer is 'Auxins'

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

Example of positive geotropism is 

  1. Closing of flowers

  2. Upwards growth of stem

  3. Downward growth of root

  4. Lateral growth of root
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Positive geotropism is the movement towards earth. In the case of roots, they grow towards the earth and are thus, called as positively geotropic. Whereas shoots are negatively geotropic.

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

Irritability/Reactivity/Sensitivity of a plant is

  1. Response to stimulus in soil

  2. Response to a change in environment

  3. Movement caused by an external force

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

Irritability, reactivity and sensitivity are excitatory response shown by plants to respond to changes in their environment. The most common response shown by plants is movement in response to environment change. For example, closing of leaves of Mimosa pudica on touching or closing of traps on a Venus fly trap.

Thus, the correct answer is option B. 

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

The movement of plant organs in response to force of gravity is called

  1. Phototropism

  2. Thigmotropism

  3. Geotropism

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

The movement of plant part in response to contact with a solid touch is called as thigmotropism. The movement of plant part in response to light is called as phototropism. The movement of plant part in response to force of gravity is called as geotropism. The movement of plant part in response to external chemical stimulus is called as chemotropism.

Thus, the correct answer is option C.

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

The stem bends upwardly and root downwardly under the influence of gravity because

  1. Of nature of stem and root

  2. Stem is photonastic and root geonastic

  3. Stem is negatively geotropic and root positively geotropic

  4. Stem is negatively hydrotropic and root positively hydrotropic
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The movement of plant part in response to force of gravity is called as geotropism. The movement of plant part towards the gravity is called as positive geotropism. Roots show positive geotropic movement. The movement of plant part away from the gravity is called as negative geotropism. Stems show negative geotropic movement. 

Thus, the correct answer is option C.

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

.......... is a plant hormone which inhibits growth leading to wilting of leaves.

  1. Absicic acid

  2. Gibberillins

  3. Auxins

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

Wilting of leaves is the loss of rigidity and caused when turgor pressure is lignified and reach zero it happens in the inadequate water supply and is caused by the hormone abscisic acid to prevent water loss.

So the correct option is 'Abscisic acid'.

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

When light falls on a part of the plant, a hormone called .......... which is synthesized at the tip of the shoot helps the cells to grow longer.

  1. Gibberellins

  2. Cytokinins

  3. Ethylene

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

Auxin is the hormone that stimulates cell elongation and growth. In the shoot when light falls on it the hormone gets activated and also promote the movement of shoot towards the light.

So the correct option is 'Auxin'.

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

Phototropism of stem and geotropism of root are due to

  1. Epinasty and hyponasty

  2. Effect of light

  3. Differential hormonal effect

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

Phototropism of shoot and geotropism of root are due to several hormonal action. The hormones responsible include auxin plant hormone. Auxin is responsible for the growth of shoot positively phototrophic. Auxin also induces apical dominance in shoots.

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

Growth of plant in response to external factors is called 

  1. Tropic movement

  2. Movement

  3. Secondary growth

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

A tropism is a biological phenomenon, indicating growth or turning movement of a biological organism, usually a plant, in response to an environmental stimulus. Tropisms are typically associated with plants (although not necessarily restricted to them). Where an organism is capable of directed physical movement (motility), movement or activity in response to a specific stimulus is more likely to be regarded by behaviorists as a taxis (directional response) or a kinesis (non-directional response).
Therefore, the correct answer is option A.

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

The movement of a plant in response to the concentration of water is known as hydrotropism.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The movement of plant in response to water is known as hydrotropism. The movement or direction of growth depends upon the concentration or gradient of water. Auxin plays an important role in bending of roots towards water. It causes on side of roots to grow faster and the other side is grows slowly. This leads to bending of roots towards water.
So, the given statement is true.