Tag: biology

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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

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.

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

Geotropic response of roots is due to

  1. Inhibition of stem growth

  2. More growth on lower side

  3. More growth on upper side

  4. Uniform growth
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. Geotropism is the plant response to the gravity. Root shows positive geotropism and shoot shows negative geotropism. In stems, auxin accumulates towards the lower side. It results in increase in cell expansion and results in the shoot growing upright. In roots, auxin accumulates towards the lower side. However, it inhibits cell expansion and roots grow 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

Drooping of Tamarind leaves after sunset is

  1. Phototropism

  2. Phototaxis

  3. Photonasty

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

Phototropism is the growth of plant in response to the light stimuli. Drooping of tamarind leaves after sunset is due to phototropism. Phototaxis is the movement shown by organism in the direction of the external light stimuli. Photonasty is the nastic movement shown by organism in response to the external light stimuli. Chemotaxis is the movement shown by organism in the direction of the external chemical stimuli. 

Thus, the correct answer is 'Phototropism'.

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. Upward growth of stem

  3. Downward growth of root

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

Geotropism is the response of plant parts to the gravity. Negative geotropism is growth of part of plant against the gravity. Positive geotropism is growth of part of plant in the direction of gravity. Downward growth of roots is example of positive geotropism. Primary stems grows against the gravity in upward direction and thus shows negative geotropism. 

Thus, the correct answer is 'Closing of flowers'.

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

Thigmotropism is best exhibited by

  1. Lamina

  2. Tendrils

  3. Root apex

  4. Thorns
Reveal answer Fill a bubble to check yourself
B 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. 

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

Sensation of phototropism is perceived by

  1. Root tip

  2. Shoot tip

  3. Axillary bud

  4. Node
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The area of the plant which perceives a stimulus is called as perceptive region. Tip of the shoot is the perceptive region for the sensation of phototropism. The area of the plant which shows the response is called as responsive region. 
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

Tendrils exhibit/twining of tendrils is due to

  1. Thigmotropism

  2. Seismonasty

  3. Heliotropism

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

The movement of plant part in response to contact with a solid touch is called as thigmotropism. The twining movements due to support seen in tendrils and twiners is an example of thigmotropism. Seismonasty is the nastic response of a plant to touch or vibration. Dropping of leaves of Mimosa pudica upon touching is due to seismonasty. Heliotropism is a growth movement or bending of stem in the direction of the light. It is also called as solar tracking. Diageotropism is plant part response to the gravity such that it grows horizontal to the gravity.

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

The movement or growth of any part of a plant in response to an external stimulus is called tropism or tropic movement.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The movement or growth of any part of a plant in response to an external stimulus is called tropism or tropic movement because most of the time the root grows underground and stem grows up to the ground and bending of stem towards light are the good examples of negative and positive phototropism.

So the statement is 'True'.

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

Pollen tube growth is an example of _______________.

  1. Geotropism

  2. Chemotropism

  3. Thigrnotropism

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

Pollen tube growth down the style toward the ovule is guided by chemical signals released by the synergids, making it a classic example of chemotropism. Geotropism relates to gravity, and heliotropism relates to sunlight.