Photorespiration occurs when RuBisCO catalyzes oxygenation of RuBP instead of carboxylation, which happens under high O2 and low CO2 conditions.

Abscisic acid is the stress hormone that promotes stomatal closure during drought by reducing guard cell turgor pressure, thereby reducing water loss.

Active transport is entirely dependent on metabolic activities and ATP availability. It requires energy to move substances against their concentration gradient.

Magnesium is the central atom in the porphyrin ring of chlorophyll molecules, making it essential for photosynthetic light absorption.

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.

The Calvin cycle (light-independent reactions) takes place in the stroma of chloroplasts, where CO2 is fixed and glucose is synthesized.

RuBisCO catalyzes the carboxylation of RuBP with CO2 to form 3-phosphoglycerate, the first stable product of dark reactions in C3 plants.

Apparent photosynthesis (net photosynthesis) represents the actual photosynthesis minus respiration measured as the gaseous exchange in the plant.

Phloem transport is bidirectional and can move sugars upwards or downwards depending on source-sink relationships and requires metabolic energy.