Tag: biology

Questions Related to biology

Which of the following regulates phototropism?

biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

  1. Ethylene gas

  2. Abscisic acid

  3. Auxin

  4. Gibberellins

  5. Cytokinins

Show answer
Correct Option: C
Explanation:

The directional growth of organisms in response to light is called phototropism. In plants, aerial shoots usually grow towards the light. The phototropic response is controlled by auxin.

Which of the following is a gaseous hormone?

biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

  1. Kinetin

  2. Zeatin

  3. Auxin

  4. Ethylene

Show answer
Correct Option: D
Explanation:
  • Ethylene is a gaseous hormone, which stimulates transverse or isodiametric growth but retards the longitudinal one. 
  • It is a gas that forms through the break down of methionine, which is in all cells. 
  • It has very limited solubility in water and does not accumulate within the cell but diffuses out of the cell and escapes out of the plant.
  • Thus, the correct option is D.

A plant capable of reducing toxic cyanide waste into non toxic form is

biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

  1. Pseudomonas

  2. Jatropha curcas

  3. Gibberella fusarium

  4. Mirabilis Jalaplia

Show answer
Correct Option: C
Explanation:
  • There are various plants which are used in the process of bioremediation. 
  • The plants are capable of taking up the toxic constituents and accumulating them in the plant body. 
  • The plant Gibberella fusarium can take up the toxic material like cyanide. 
  • The cyanide is reduced by this plant and converted to a non-toxic form. 
  • Thus, the correct answer is option C. 

Closure of stomata is caused by 

biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

  1. Auxin

  2. Gibberellin

  3. Cytokinin

  4. Abscisic Acid

Show answer
Correct Option: D
Explanation:
  • Abscisic acid is a carotenoid-derived plant hormone known to regulate critical functions in growth, development and responses to environmental stress.
  • It plays a key role in the regulation of stomatal closure by regulating ion channel activities and water exchanges across the plasma membrane of guard cells.
  • It increases the influx of calcium ions and efflux of potassium ions, which results in the closure of stomata.
  • So, the correct option is D.

Of the following which plant hormone inhibits growth?

biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

  1. Cytokynins

  2. Gibberelins

  3. Auxins

  4. Abscisic acid

Show answer
Correct Option: D
Explanation:

Abscisic acid is the plant growth hormone which is responsible for inhibiting growth. The hormone causes inhibition in the growth of the roots and shoots. The hormone also causes abscission which is the falling of the leaves, fruits and flowers. The hormone suppresses all the processes in the plants during unfavourable conditions. 

Thus, the correct answer is option D. 

Auxin does not increase

biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

  1. The plasticity of cell walls

  2. The rate of photosynthesis

  3. The uptake of water by cells

  4. Rate of respiration

Show answer
Correct Option: B
Explanation:

Auxin is a plant hormone that plays important role in plant growth. It stimulates stem elongation by increasing permeability of cells which in turn increases uptake of water by cells. It also enhances plasticity of cell walls which results in cell enlargement. It also increases the respiration rate.

Thus, the correct answer is option B.

Leaf fall can be prevented with the help of 

biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

  1. Abscisic acid

  2. Auxins

  3. Florigen

  4. Cytokinins

Show answer
Correct Option: B
Explanation:

Leaf abscission is a detachment or fall of older leaves.It occurs at the base of the petiole. When auxin is applied to the base of petiole of young leaf, the abscission is greatly suppressed. Also, it is observed that the intact leaf does not fall off because it synthesizes auxin.

Thus, the correct answer is option B.

Which is not an influence of auxins?

biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

  1. Tropical movements

  2. Bolting

  3. Parthenocarpy

  4. Apical dominance

Show answer
Correct Option: B
Explanation:

Auxin is a plant hormone which is involved in various physiological processes. It is present on the tip of the stem and helps in phototropic movement in response to light. It also maintains apical dominance where there is more growth on the stem tip and growth of lateral bud is inhibited. Auxin along with cytokinin and gibberellin helps in the process of parthenocarpy. It does not cause bolting. It does not influence flowering in the plant.

Thus, the correct answer is option B.

Match the columns and find the correct combination:

      I             II
a Auxin 1. Herring sperm DNA
b Cytokinin 2. Inhibitor of growth
c Gibberellin 3. Apical dominance
d Ethylene 4. Epinasty
e Abscisic acid 5. Induces amylase synthesis
biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

  1. a- 3, b- 1, c- 5, d- 4, e- 2

  2. a- 4, b- 5, c- 1, d- 3, e- 2

  3. a- 2, b- 1, c- 5, d- 3, e- 4

  4. a- 3, b- 1, c- 5, d- 2, e- 4

  5. a- 4, b- 1, c- 5, d- 3, e- 2

Show answer
Correct Option: A
Explanation:
Kinetin, a type of cytokinin was isolated from autoclaved herring sperm DNA. It has cell division-promoting activity. Auxin is a plant hormone. It promotes stem elongation and thus regulates apical dominance. Gibberellic acid is a plant hormone which breaks the dormancy. Before germination, it stimulates the synthesis of amylase enzyme. Amylase hydrolyzes starch into glucose which is used to provide nourishment to the seed embryo. Ethylene is a plant hormone that causes the downward bending of the plant part. This is called as epinasty. Abscisic acid is a plant hormone that acts as the inhibitor of growth.
Thus, the correct answer is option A.

Pick up correct statements.
(A) Cytokinins delay senescence
(B) Auxins regulate apical dominance
(C) Ethylene enhances seed germination
(D) Gibberellins cause falling of immature leaves

biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

  1. $a, c$

  2. $a, d$

  3. $a, b$

  4. $b, c$

  5. $b, d$

Show answer
Correct Option: C
Explanation:

Cytokinin is a plant hormone that promotes cell division. It delays senescence. Auxin promotes stem elongation and thus regulate apical dominance. Ethylene is also called as ripening hormone as it helps in the ripening of fruits. Gibberellic acid prevents falling of immature leaves. 

Thus, the correct answer is option C.