Tag: movements in plants

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

A decapitated plant exposed to unilateral light

  1. Bends away from source of illumination

  2. Bends towards the source of light

  3. Shows zigzag curvature

  4. Does not show bending movement
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The plant growth regulator that brings about the growth and bending of stem towards light is present only at the tip, i.e the apex of the stem.
So, when the tip is removed or decapitated, the part containing the PGR auxin is also lost. Hence, a decapitated plant does not show any bending when exposed to unilateral light.
Thus, the correct answer is D 'Does not show bending movement'
Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

Tropic movements occur as a result of

  1. Unidirectional effect of environmental factors on plant organs

  2. Bidirectional effect of environmental factors on plant organs

  3. Multidirectional effect of environmental factors on plant organs

  4. No effect of environmental factors on plant organs
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Tropic movement is growth movement shown by plant in response to a unidirectional external stimulus. It is specific for direction and depends on the direction of stimulus. Movement towards the direction of stimuli is called as positive tropism while movement away from stimuli is called as negative tropism. It results in positioning of the plant part in the direction of the stimulus.

Thus, 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

Turgor movements occur in response to

  1. Stimulation of amyloplasts

  2. Activation and deactivation of phytochrome

  3. Circadian rhythm
  4. Changes in ${K}^{+}$ ion concentration
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Turgor movement is a reversible change in position of a plant part due to a change in turgidity of cells. It is mostly caused by contact. In plants, turgor changes occur in thin walled cells of pulvinus present on lower side and pulvinnules present on upper side. Both side has different concentration of potassium and calcium ions. Upon touching, potassium ion concentration changes in the cells which results in turgor movement.

Thus, the correct answer is option D.

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

Thigmotropism is best seen in

  1. Root apex

  2. Stem apex

  3. Leaf apex

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

Thigmotropism is the directional response of a plant part to touch with a solid object. It is best seen in tendrils. Upon contact with the stimulus, it shows curving up towards the stimulus. Tendrils grow toward the touch stimulus, and wrap around the object.

Thus, the correct answer is option D. 

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

Pollen tubes exhibit

  1. Haptotropism

  2. Chemotropism

  3. Anemotropism

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

The movement of parts of a plant in response to a touch stimulus is called as haptotropism. The movement of parts of a plant in response to external chemical stimulus is called as chemotropism. An example is growth of the pollen tube towards the ovules. The movement of parts of a plant in response to air current is called as anemotropism. The movement of parts of a plant in response to sunlight is called as heliotropism. 

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

Tropic movements are caused by

  1. Cell division

  2. Cell elongation

  3. Loss of water

  4. Gain of water
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Tropic movement is growth movement shown by plant in response to a unidirectional external stimulus. It is specific for direction and depends on the direction of stimulus. Movement towards the direction of stimuli is called as positive tropism while movement away from stimuli is called as negative tropism. Plant part shows tropic response in terms of cell elongation. For example, in phototropism, faster cell elongation is seen on the shaded side than on the illuminated side. 

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

Entwining of Grape Vine tendril around a support is

  1. Thigmotropism

  2. Nutation

  3. Gravitropism

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

Thigmotropism is a directional growth movement in response to a touch stimulus. It is found in twining plants and tendrils. Grape vine tendril entwines around a support due to thigmotropic movement. Nutation is the bending movement shown by plant during its development. Growth movement in response to gravity is called as gravitropism. Nastic movement in response to external stimulus is called as chemonasty. 

Thus, 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

Phototropism in shoots is attributed to or phototropic movements are due to

  1. Auxin

  2. Gibberellins

  3. Cytokinin

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

Auxin is a plant hormone that plays important role in phototropism, growth movement in response to light. It promotes cell elongation. It is unequally distributed in the plant cells. It is transported towards the shady side and thus present in higher concentration. However, less auxin is transported towards the side exposed to light. Due to this, the plant grows more on the shaded side and bend in the direction of the light source. It shows positive phototropism where faster cell elongation is seen on the shaded side and less on the illuminated side. 

Thus, 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

Secondary roots are generally

  1. Diageotropic

  2. Positively geotropic

  3. Ageotropic

  4. Plagio-geotropic
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Diageotropic is the part of plant that grows at a right angle to the direction of gravity. Example of diageotropic include rhizome, runner. Plagiogeotropic is the part of plant that grows at intermediate angle between $0^o$ and $90^o$ to the direction of gravity. Secondary roots are examples of plagiogeotropic. Positively geotropic is part of plant that grows in the direction of gravity. Roots are examples of positively geotropic organ.
So, the correct answer is 'Plagio-geotropic'
Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

Phototropism is because of unequal distribution of auxin under the influence of unilateral (one sided) illumination as auxin

  1. Moves from illuminated side to shaded side

  2. Synthesis is checked on illuminated side

  3. Destroyed on illuminated and not on shaded side

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

Auxin is a plant hormone that plays important role in phototropism, growth movement in response to light. It promotes cell elongation. It is unequally distributed in the plant cells. It is transported towards the shady side and thus present in higher concentration. However, less auxin is transported towards the illuminated side. Auxin synthesis is inhibited on illuminated side. It moves from the illuminated side to shaded side. Due to this, the plant to grow more on the shaded side and bend in the direction of the light source. It shows phototropic response where faster cell elongation is seen on the shaded side than on the illuminated side. 

Thus, the correct answer is option D.