Tag: chemical coordination in plants

Questions Related to chemical coordination in plants

Match the Column-I and Column-II.

Column-I Column-II
(i) Auxin (A) Adenine derivatives
(ii) Gibberellin (B) Carotenoid derivatives
(iii) Cytokinin (C) Terpins
(iv) ABA (D) Indole compounds
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. i-B, ii-A, iii-D, iv-C

  2. i-D, ii-B, iii-A, iv-C

  3. i-B, ii-A, iii-C, iv-D

  4. i-D, ii-C, iii-A, iv-B

Show answer
Correct Option: D

A high concentration of synthetic auxin is generally used for

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. Weed control

  2. Preventing the growth of the lateral buds

  3. Enhancing root initiation

  4. Controlling of cell enlargement

Show answer
Correct Option: A
Explanation:

In the course of research on auxin biology, many compounds with noticeable auxin activity were synthesized. Many of them had been found to have the economical potential for man-controlled growth and development of plants in agronomy. Auxins are toxic to plants in large concentrations. They are most toxic to dicots and less so to monocots. Because of this property, synthetic auxin herbicides, including 2,4-D and 2,4,5-T, have been developed and used for weed control. However, synthetic auxins, especially 1-naphthaleneacetic acid (NAA) and indole-3-butyric acid (IBA), are also commonly applied to stimulate root growth when taking cuttings of plants or for different agricultural purposes such as the prevention of fruit drop in orchards. Used in high doses, auxin stimulates the production of ethylene. Excess ethylene (also native plant hormone) can inhibit elongation growth, cause leaves to fall (abscission), and even kill the plant. 

Therefore, the correct answer is option A.

During adverse environmental conditions, plants develop a stress hormone, which 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. Abscisic acid

  2. Ethylene

  3. Benzyl amino purine

  4. Dichlorophenoxy acetic acid

Show answer
Correct Option: A
Explanation:
Abscisic acid or ABA plays a regulatory role in many physiological processes in plants. Different stress conditions such as water, cold, light, and temperature result in increased amounts of ABA. The action of ABA involves modification of gene expression and analysis of responsive promoters revealed several potential cis- and trans- acting regulatory elements. Stress may induce common responses such as enhancement of plant hormones. For instance, wounding can induce the production of increased ethylene, auxin, and abscisic acid (ABA). Since, many kinds of stresses including water, salt, and cold temperatures, induce ABA synthesis, ABA may be considered a plant stress hormone. It regulates several important aspects of plant growth and development. Recent studies have demonstrated a pivotal role for ABA in modulation at the gene level of adaptative responses for plants in adverse environmental conditions.

Which among the following hormones is toxic to plants in large concentrations, regulates protein synthesis and causes bud formation and root initiation?

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

  2. Auxin

  3. Cytokinin

  4. Gibberellins

Show answer
Correct Option: B
Explanation:

  • Auxins are a group of hormones that positively influence cell enlargement, bud formation, and root initiation. 
  • In conjunction with cytokinins, they control the growth of stems, roots, and fruits, and convert stems into flowers. Auxins were the first class of growth regulators discovered. 
  • They affect cell elongation by altering cell wall plasticity. Auxins act to inhibit the growth of buds lower down the stems, and also to promote lateral and adventitious root development and growth. 
  • Leaf abscission is initiated by the growing point of a plant ceasing to produce auxins. Auxins in seeds regulate specific protein synthesis, as they develop within the flower after pollination, causing the flower to develop a fruit to contain the developing seeds. 
  • Auxins are toxic to plants in large concentrations, they are most toxic to dicots and less so to monocots. 

Therefore, the correct answer is option B.

Which hormone works during seed dormancy?

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. Gibberellins

  3. Abscisic acid

  4. Cytokinins

Show answer
Correct Option: C
Explanation:

  • Abscisic acid is one of the most important plant growth regulators. This class of PGR is composed of one chemical compound normally produced in the leaves of plants, originating from chloroplasts, especially when plants are under stress. In general, it acts as an inhibitory chemical compound that affects bud growth, and seed and bud dormancy. 
  • It mediates changes within the apical meristem, causing bud dormancy and the alteration of the last set of leaves into protective bud covers. 

Therefore, the correct answer is option C.

If a person tests plant hormones for increasing the crop yield, he sprays a large plot with a selected hormone to determine its effect in hybrid vigor. Which of the following he should avoid?

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. $2, 4-$D

  2. IAA

  3. Gibberellin

  4. Cytokinin

  5. Abscisic acid

Show answer
Correct Option: A
Explanation:

There are five major types of plant hormones. Abscisic Acid also called ABA is one of the most important plant's growth regulators and under water stress, this hormone plays a role in closing the stomata. Auxins are hormones that  positively influence cell enlargement, bud formation and root initiation. Cytokinins tend to positively influence cell enlargement, bud formation and root initiation. Others are ethylene regulates the fruit ripening and Gibberellins stimulates the flower production, cell elongation. Whereas 2, 4-D is not a plant hormone but a chemical weedicide. 

Match the columns and choose the correct combination.

    I           II
(a) Cytokinin (p) Stress hormone
(b) Auxins (q) Ripening of fruits
(c) Abscisic acid (r) Apical dominance
(d) Ethylene (s) Bolting
(t) Richmond-Lang Effect
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 - t, b - r, c - p, d - q

  2. a - t, b - r, c - p, d - s

  3. a - r, b - s, c - q, d - p

  4. a - q, b - s, c - t, d - r

Show answer
Correct Option: A
Explanation:

Cytokinin is a plant hormone that produces the Richmond Lang effect. It inhibits ageing process of the plant. Auxin is a plant hormone that induces apical dominance. It promotes the growth of stem tip and inhibits the growth of lateral buds. Abscisic acid is a plant hormone. It is also called as stress hormone as under stress environmental condition, its concentration increases. It induces seed dormancy. Ethylene is a plant hormone. It is also called as ripening hormone as it induces ripening of fruits. 

Thus, the correct answer is option A.

Hormones used to speed up malting in Barley, promote flowering in Pineapple and delaying leaf senescence are respectively

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, Gibberellin and Cytokinin

  2. Gibberellin, Cytokinin, Auxin

  3. Gibberellin, Auxin, Cytokinin

  4. Cytokinin, Auxin, Gibberellin

  5. Auxin, Cytokinin, Gibberellin

Show answer
Correct Option: C
Explanation:

Gibberellic acid is a plant hormone. It stimulates stem elongation, germination, flowering. It also causes fruit elongation and delays senescence. Hence in brewery industry, it is used to speed up malting process. Auxin is a plant hormone which is used to induce flowering in pineapple as it induces synthesis of ethylene. Cytokinin is a plant hormone that stimulates cell division. It delays the senescence in leaves. 

Thus, the correct answer is option C.

Identify the incorrect matched pair.

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 - Phototropism

  2. Gibberellin - Foolish seeding disease of rice

  3. Ethylene - Induces fruit ripening

  4. Cytokinin's - Promotes apical dominance

Show answer
Correct Option: A

Match the following columns.

Column I(Bioassays of phytohormones) Colum  II(Characteristics of phytohormones)
a. Avena curvature test (i) Delay leaf senescence
b. Chlorophyll preservation test (ii) Promote female flowers in cucumber
c. Triple response test (iii) Initiate rooting in stem cutting
d. Cotton test (iv) Antagonist to GAs
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(iii), b(i), c(iv), d(ii)

  2. a(iii), b(ii), c(i), d(iv)

  3. a(iii), b(i), c(ii), d(iv)

  4. a(iii), b(iv), c(ii), d(i)

Show answer
Correct Option: A