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.
Diffusion is a passive process that does not require ATP; substances move along the concentration gradient.
The cohesion-tension theory explains water transport in tall trees through cohesive forces between water molecules and tension created by transpiration.
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.
Phototropism is the directional growth response of plants towards light, mediated by differential distribution of auxin.
Auxin promotes cell elongation and causes apical dominance by inhibiting lateral bud growth through differential distribution.
Turgor pressure changes in guard cells due to osmotic changes regulate stomatal opening. ABA plays a secondary regulatory role.