Biology

Plant Growth and Hormones

727 Questions

Plant growth and hormones is a vital topic in biology that covers the physiological effects of different plant regulators like auxins, gibberellins, and cytokinins. These concepts are frequently tested in various general science sections of competitive exams. Practicing these questions helps clarify complex mechanisms like vernalisation, senescence, and tropism for test takers.

Abscisic acid effectsCytokinin functionsAuxins and tropismPlant tissue cultureSenescence in plantsNatural plant hormones

Plant Growth and Hormones Questions

Multiple choice

What are anthesins required for?

  1. Growth of stem

  2. Formation of flowers

  3. Dormancy of seeds

  4. Inhibition of elongation of stem
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Anthesins are required for flower formation.

Multiple choice

Which of the following is a major function of cytokinin?

  1. It inhibits elongation of stem.

  2. It causes dormancy of seed.

  3. It stimulate cell division, even in non-meristematic tissues.

  4. It causes parthenocarpy.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cytokinin, in presence of auxins, stimulates cell division, even in non-meristematic tissues.

Multiple choice

Which among the following is a phytohormone?

  1. Indoline

  2. Indole-3-acetic acid

  3. Inositol

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

Indole-3-acetic acid is a heterocyclic compound that is a phytohormone called auxin. This colourless solid is native plant compound, potent and the most important auxin. The molecule is derived from indole and containing a carboxymethyl group (acetic acid).

Multiple choice

The term stress hormone is used to refer

  1. ethylene

  2. ABA

  3. gibberellins

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

ABA is a stress hormone. Abscisic acid appears to maintain winter dormancy in buds. It prevents seeds from germinating while still attached to the parent plant, and it inhibits stem elongation. Through its effects on stomatal opening, it also regulates gas and water exchange between leaves and the atmosphere.

Multiple choice

The famous Avena curvature test conducted by F.W. Went proves that

  1. Plant growth regulators are auxins.

  2. Shoot apex is the site for the synthesis of growth regulating substance. .

  3. ABA is a growth inhibitor.

  4. Auxins exercise apical bud dominance.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The famous Avena curvature test conducted by F.W. Went proves that shoot apex is the site for the synthesis of growth regulating substance.

Multiple choice

Which among the following mechanisms of action of a herbicide affects the cell membrane production in the meristems of the grass plant leading to its death?

  1. ACCase inhibitors

  2. EPSPS inhibitors

  3. Synthetic auxins

  4. Photosystem I inhibitors

  5. Photosystem II inhibitors
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

ACCase inhibitors compounds kill grasses. Acetyl coenzyme A carboxylase (ACCase) is part of the first step of lipid synthesis. Thus, ACCase inhibitors affect cell membrane production in the meristems of the grass plant. The ACCases of grasses are sensitive to these herbicides, whereas the ACCases of dicot plants are not.