This set of Life Sciences Multiple Choice Questions & Answers (MCQs) focuses on “Plant Hormones”.
1. Growth regulators, which control plant growth and development are called___________
a) Secondary metabolites
b) Macro element
c) Nonessential elements
Explanation: Phytohormones or plant hormones are the small organic compound which is synthesized by specific cells/tissues in low concentration and promote the growth and development of the plant.
2. Growth in plants is mainly driven by turgor pressure.
Explanation: During the growth, cells in plant increase in the volume and become highly vacuolated, this is basically due to the turgor pressure. Plant growth is defined as an irreversible increase in size or volume.
3. Which of the following is NOT a plant hormone?
d) Salicylic acid
Explanation: Corticosteroid is an animal hormone, which is produced in the adrenal cortex of the vertebrates while brassinosteroid, polyamines and salicylic acid are plant hormones.
4. Name the plant in which auxin was first discovered?
Explanation: Auxin is a first plant hormone which was discovered by Frits Went in the tip of the oats (Avena sativa) coleoptiles.
5. Which of the following is NOT a naturally occurring auxin?
a) Indole 3-acetic acid (IAA)
b) Indole 3-butyric acid (IBA)
c) Phenyl acetic acid (PAA)
Explanation: 2, 4-D is an organic compound and is known as synthetic auxin which is marketed as a herbicide.
6. Name the amino acid which acts as a precursor of auxin biosynthesis?
Explanation: The basic chemical structure similarity between indole 3-acetic acid and tryptophan proves the connection between them. The conversion of tryptophan to auxin takes place by tryptophan dependent pathway.
7. Mark the one, which is NOT a physiological effect of auxin?
a) Cell elongation
b) Stem elongation
c) Cell differentiation
Explanation: Stem elongation is the physiological effect of Gibberellins not Auxin. Auxin involves in cell elongation, rooting, and cell differentiation.
8. Name the site of Gibberellins synthesis
b) Coleoptile tip
c) Young leaves
Explanation: Biosynthesis of Gibberellins takes place in the apical tissues and young leaves of the plant. Sometimes root tissues also produce Gibberellins.
9. Gibberellin that is synthesized in the shoot transported to different parts of the plant by which medium?
b) Sieve tube
c) Aleurone layer
Explanation: After synthesis Gibberellins transported to rest of the plant by phloem but the Gibbrellins which synthesized in roots are transported to shoots by the xylem.
10. What is bolting?
a) Internode elongation
d) Shoot apical meristem
Explanation: Bolting has defined as a phenomenon of Internode elongation just before the flowering of the plant. It is normally triggered by environmental signals.
11. Which of the following plant hormone is responsible for seed germination?
d) Abscisic acid
Explanation: Gibberellin activates vegetative growth of the embryo by promoting the utilization of reserve food which is stored in the endosperm.
12. Name the first naturally occurring cytokines.
d) Isopentenyl adenine
Explanation: Zeatin was the first naturally occurring cytokines, which was isolated by Miller and Letham in 1955 from the corn.
13. Which of the following plant hormone causes a delay in leaf senescence?
a) Abscisic acid
Explanation: Senescence is an aging process which is an energy driven genetic program. Presence of cytokines delay in leaf senescence.
14. Name the stress hormone of the plant.
b) Abscisic acid
Explanation: Abscisic acid is a plant stress hormone which was first identified as a compound responsible for abscission of cotton fruits.
15. Deficiency in which of the following hormone causes dwarfism in the plant?
b) Abscisic acid
Explanation: Brassinosteroid is chemically similar to the animal hormone and are responsible for the promotion of cell division, cell elongation and differentiation.
Sanfoundry Global Education & Learning Series – Life Sciences.
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