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Multiple choice 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

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

  1. Ethylene

  2. Auxin

  3. Cytokinin

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

Multiple choice 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

Which hormone works during seed dormancy?

  1. Auxin

  2. Gibberellins

  3. Abscisic acid

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

Multiple choice 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

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?

  1. $2, 4-$D

  2. IAA

  3. Gibberellin

  4. Cytokinin

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

Multiple choice 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

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

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

Multiple choice 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

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

  1. Auxin, Gibberellin and Cytokinin

  2. Gibberellin, Cytokinin, Auxin

  3. Gibberellin, Auxin, Cytokinin

  4. Cytokinin, Auxin, Gibberellin

  5. Auxin, Cytokinin, Gibberellin
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

Multiple choice 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

Identify the incorrect matched pair.

  1. Auxin - Phototropism

  2. Gibberellin - Foolish seeding disease of rice

  3. Ethylene - Induces fruit ripening

  4. Cytokinin's - Promotes apical dominance
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cytokinins promote lateral bud growth and counteract apical dominance. Therefore, stating that cytokinins promote apical dominance makes the pair incorrectly matched.

Multiple choice 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

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

  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)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Avena curvature test (Auxin/rooting), Chlorophyll preservation (Cytokinin/senescence), Triple response (Ethylene/female flowers), Cotton test (Auxin/antagonist).

Multiple choice 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

Which of the following are synthetic phytohormone?

  1. IBA, IAA, BAP
  2. $2, 4$-D, NAA, BAP

  3. Zeatin, IBA, IAA
  4. NAA, IAA, $2, 4$-D
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • The plant growth regulators (PGRs) or phytohormones are small, simple molecules of diverse chemical composition. For example, auxins, gibberellins, cytokinins, abscisic acid, and ethylene.
  • NAA (naphthalene acetic acid) and 2, 4-D (2, 4-dichlorophenoxyacetic)are synthetic auxins.
  • 6-Benzylaminopurine, benzyl adenine, BAP  is a first-generation synthetic cytokinin that elicits plant growth and development responses, setting blossoms and stimulating fruit richness by stimulating cell division.
  • Hence 2,4-D, NAA, BAP  are synthetic phytohormone.
  • So, the correct answer is '2,4-D, NAA, BAP '.
Multiple choice 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

Phytohormone which promotes nutrient mobilisation, also help in?

  1. Induce flowering in mango

  2. Fruit thinning of cotton

  3. Production of new leaves and chloroplasts

  4. Seed development and dormancy
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pytohormone which causes mobalization of nutrients is cytokinin and  it also helps in the formation of new leaves and chloroplast. 

Multiple choice 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

In plants, the chemical control is brought about by 

  1. Phytohormones

  2. Hormones

  3. Enzymes

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

A- Phytohormones are plant hormones. These are organic substances which are produced in the plants. They bring about total control over growth and other physiological functions in the organism.