Govt. Exams
Entrance Exams
At compensation point, the rate of CO2 fixation in photosynthesis equals the rate of CO2 release in respiration, resulting in net zero gas exchange.
Plasmodesmata are cytoplasmic bridges allowing symplastic movement of water, minerals, and even macromolecules like proteins and RNA between adjacent cells.
Stomatal oscillation refers to the dynamic opening and closing of stomata in response to changing environmental conditions to maintain optimal gas exchange while reducing water loss.
Ethylene accumulates in leaf petioles during water stress, promoting abscission layer formation, leading to leaf shedding. ABA increases ethylene production.
Wilting occurs when transpiration rate exceeds the water absorption rate by roots, even with adequate soil water, due to environmental stress or damaged vascular tissue.
Turgor pressure in sieve tubes is involved in phloem transport, not xylem transport. Water transport in xylem is driven by root pressure, capillarity, and transpirational pull.
Guttation occurs due to root pressure being high at night (stomata closed), causing water exudation through hydathodes at leaf tips.
Active transport is entirely dependent on metabolic activities and ATP availability. It requires energy to move substances against their concentration gradient.
The light saturation point is the light intensity beyond which photosynthesis does not increase, indicating maximum rate of photosynthesis has been achieved.
Stomatal opening and closing are mainly controlled by hydroactive movements, which involve osmotic changes in guard cells due to potassium ion accumulation.
