Plant Hormones (GATE)
Plant hormones including auxin, gibberellin, cytokinin, ethylene, abscisic acid, brassinosteroids, and related growth regulators
Questions
Paclobutrazol is a plant growth retardant which is antagonist against
- auxin
- gibberellin
- jasmonates
- ethylene
In yang cycle, which enzyme is responsible for conversion of S-adenosyl L-methionine to 1-amino cyclopropane carboxylate, that on simple oxidation, yields ethylene?
- ACC oxidase
- ACC synthase
- ACC N-malonyl transferase
- SAM synthetase
Ethylene induces flowering in
- chrysanthamum
- pineapple
- submerged plants
- petunia
Which of the following changes is induced by auxins in roots?
- Expansion
- Elongation
- Swelling
- Coleoptile growth
Polyamines are strongly basic hormones with low molecular weight that have been found in all organisms studied so far. What role do they play?
- Inhibition of shoot branching
- Serve as signal in hormonal and defence responses
- Affect the processes of mitosis and meiosis
- Stimulate xylem differentiation
Gibberellins signal starch hydrolysis and break seed dormancy. Which enzyme production is induced by gibberellins to initiate this function?
- Alpha-amylase
- Beta-amylase
- Isoamylase
- Glucosyl transferase
Which of the following process is stimulated if auxin concentration is higher then cytokinin concentration?
- Cell elongation
- Cell division
- Rooting
- Xylem tissue generation
Which of the following sentences are in accordance with direct inhibition hypothesis?
- Auxins from axillary buds travel up to apical buds to stimulate bud growth.
- Cytokinins move from roots to shoot signalling lateral bud growth.
- Cytokinins move from shoot to root to induce root morphogenesis.
- Auxin from apical buds travel down shoots to stimulate auxiliary bud growth.
In the process of seed germination, abscisic acid acts antagonistically to
- auxins
- gibberellins
- cytokinin
- brassinosteroids
Which pathway is used for gibberellin biosynthesis?
- Mevalonic acid pathway
- MEP (Methyl Erythritol Phosphate) pathway
- Yang cycle
- Shikimate pathway
In which hormone's biosynthesis pathway is adenosine phosphate-isopentenyltransferase involved?
- Cytokinin
- Gibberellin
- Auxin
- Ethylene
What is the primary action of brassinosteroids?
- Control agents for pollen leaf incompatibility
- Seed germination inducers
- Plant defence substances
- Plant strengthening substances
Which of the following is not an effect produced by abscisic acid in plants?
- Inhibition of fruit ripening
- Inhibition of synthesis of kinetin nucleotide
- Inhibition of short day induced flower initiation in Pharbitus nil
- Action on endodermis to prevent growth of roots when exposed to salty conditions
Pyrabactin (a pyridyl-containing ABA activator) is a naphthalene sulphonamide hypocotyl cell expansion inhibitor. Which of the following sentences are true with respect to pyrabactin?
- It is very sensitive to light.
- It is a naturally produced stress hormone.
- It is an antagonist of ABA.
- It is an agonist of the seed ABA signalling pathway.
Gibberellins were first recognised by Elichi Kurosawa while studying
- foolish seedling disease in rice
- sheath brown rot
- crown sheath rot
- leaf smut