Govt. Exams
Entrance Exams
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.
Transpiration increases with decrease in humidity as the vapor pressure gradient between leaf and atmosphere increases.
In C4 plants, CO2 combines with PEP to form oxaloacetate (4-carbon compound) in the mesophyll cells, unlike C3 plants where 3-PGA is formed.
P680 is a special chlorophyll a molecule in the reaction center of PSII that absorbs light at 680 nm wavelength.
Red light (600-700 nm) is most effectively used in photosynthesis, followed by blue light. Green light is poorly absorbed.
