Eduqo
General Science›Ch 3: Biology›Plant Physiology
Master Photosynthesis, Transpiration and Plant Hormones for Competitive Exams
Plants depend on precise physiological processes like photosynthesis for energy, transpiration for water movement, and hormones for growth regulation. Mastering these mechanisms is essential for cracking SSC, Railway, and Defence science questions.
Memory Hooks
| Hormone | Primary Function | Key Note |
|---|---|---|
| Auxin | Cell elongation, Apical dominance | Discovered by Darwin |
| Gibberellin | Stem elongation, Seed germination | Bolting effect |
| Cytokinin | Cell division, Delay aging | Works with auxin |
| Ethylene | Fruit ripening | Gaseous hormone |
Photosynthesis
(Light energy to food)
Light energy to food
Occurs in chloroplasts using carbon dioxide and water.
Transpiration
(Water loss via stomata)
Water loss via stomata
Creates an upward suction pull for mineral transport.
Abscisic Acid
(Stress hormone regulator)
Stress hormone regulator
Closes stomata rapidly during drought conditions.
Phototropism
(Bending towards light)
Bending towards light
Auxin redistributes to the shaded side causing stem curvature.
Ethylene is a liquid hormoneEthylene is a gaseous hormone
Always remember ethylene is unique for being a gas at room temperature.
ABA promotes plant growthABA is a growth inhibitor
Abscisic acid inhibits growth, promotes dormancy, and closes stomata.
Transpiration cools the soilTranspiration cools the plant leaf
Evaporative water loss cools the leaf surface, protecting plant proteins.
Q1.Which plant hormone is gaseous in nature and promotes fruit ripening?
Q2.Which hormone is primarily responsible for inducing stomatal closure during water stress?