Govt. Exams
Entrance Exams
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.
CAM plants open stomata at night to minimize water loss and fix CO2 into malic acid, which is released during the day for photosynthesis.
At compensation point, the rate of photosynthesis equals the rate of respiration, resulting in no net gas exchange.
Root pressure is a positive pressure that pushes water upwards in xylem due to active uptake of minerals by root cells.
The Casparian strip is a waxy impermeable band in the endodermis that blocks apoplastic water movement and ensures selective uptake.
Excessive transpiration leads to water loss exceeding water uptake, causing wilting due to loss of turgor pressure in cells.
Turgor pressure changes in guard cells due to osmotic changes regulate stomatal opening. ABA plays a secondary regulatory role.
