Tag: tropic and nastic 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

Curling of tendrils is due to 

  1. Thigmotropism

  2. Phototropism

  3. Chemotropism

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

Tendrils are the threadlike organs of plants which are actually specialized stem, leaf or petiole and used for climbing, support or attaching to another for parasitic growth. Most climbing plants such as vines develop tendrils that tend to coil around objects that support it. This feature of the tendrils is due to a phenomenon called thigmotropism - directional growth movement of curvature in response to stimulus or contact.

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

Geotropic response of root is due to

  1. Higher auxin content of stem

  2. Higher growth on upper side of root

  3. Lower rate of growth in the stem

  4. Higher rate of growth in the stem
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Auxin is a plant hormone that plays important role in the growth of stem and roots to gravity. Gravitropism is a plant growth response to gravity. Root shows positive gravitropism and shoot shows negative gravitropism. Auxin content is lower on the upper side and more concentration occurs in lower side of the root and stem. This stimulates stem elongation and thus stem grows upwards. In roots, higher growth on upper side occurs due to lower auxin content. This inhibits root elongation and thus root grows downwards showing geotropic response. 

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

Cholodny-Went theory is connected with

  1. Photomorphogenesis

  2. Phototropism

  3. Geotropism

  4. Both B and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The tropic movement of plant part in response to gravity of earth is called geotropism. Cholodny-Went theory is based on phototropism. It proposes that auxin hormone is synthesized in the coleoptile tip. It moves down the coleoptile. Hence, tip has higher concentration of auxin that causes the coleoptile to bend towards the light source and lower regions have an auxin asymmetry. This results in differential growth in geotropism. 
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

More concentration of auxin in horizontally placed plants, under the influence of gravity, occurs in

  1. Upper side

  2. Lower side

  3. Both upper and lower side

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

Auxin is a plant hormone that plays important role in the growth of stem and roots to gravity. Gravitropism is a plant growth response to gravity. Root shows positive gravitropism and shoot shows negative gravitropism. When plant is placed horizontally, more concentration occurs in lower side of the root and stem. This stimulates stem elongation and thus stem grows upwards. This inhibits root elongation and thus root grows downwards. 

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

Movements in Mimosa pudica are due to turgor changes in

  1. Pulvinus and pulvinnules

  2. Pinna and pinnules

  3. Leaf and leaflets

  4. Petiole and rachis
Reveal answer Fill a bubble to check yourself
A 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. Mimosa pudica shows dropping of leaves upon touching. In this sensitive plant, the pulvinus and pulvinnules are responsible for the folding of the leaves. In this, turgor changes occur in thin walled cells of pulvinus present on lower side and pulvinnules present on upper side. This results in folding of pinnules and pinnae comes together causing drooping of the compound leaves.

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

Tendrils and twiners come in contact with their support by means of

  1. Nutation

  2. Thigmonasty

  3. Thigmotropism

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

Nutation is the bending movements shown by some plant parts due to the unequal rate of growth of different parts of plants. Thigmonasty is the nastic response of a plant to touch. The movements of tentacles of Drosera when comes in contact with insect is due to thigmonasty. The movement of plant part in response to contact with a solid touch is called as thigmotropism. The curvature movements due to support seen in tendrils and twiners is an example of thigmotropism. The movement of parts of a plant in response to air current is called as anemotropism. 

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

Phototaxis is shown by

  1. Zoospores of Ulothrix

  2. Chlamydomonas

  3. Volvox

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

Phototaxis is a movement of part of organism in response to the light. This phenomenon is exhibited by zoospores of certain algae like Ulothrix, Chlamydomonas, Volvox, Cladophora. They exhibit positive phototaxic movement in presence of diffused light and negative phototaxic movement in presence of intense light.

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

Choose the correct answer from the alternatives given.
Which of the following lights is the most effective in phototropism?

  1. Red

  2. Far-red

  3. Blue`

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

Phototropism in plants is primarily mediated by phototropins, which are blue-light receptors. Blue light is significantly more effective at inducing phototropic curvature than red or green light.

Multiple choice biology life processes in living organism movements in plants coordination in plants tropic and nastic movements in plants

Centromere is a part of chromosome which helps in the 

  1. Division of centrosomes

  2. Formation of spindle fibres

  3. Movement of chromosomes

  4. Formation of nuclear spindle
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Centromere joins the microtubules of 'Chromosomal spindle fibres and helps in the movement of chromosome during cell division. Centromere also plays an important role in the polymerization of tubulin protein used in the formation of microtubules. Hence it is helpful in attaching the chromosome with spindle fibres.