Govt Exams
The cytochrome b6f complex transfers electrons between PSII and PSI while simultaneously pumping H+ ions into thylakoid lumen for chemiosmosis.
In the Z-scheme, electrons from PSI reduce NADP+ to NADPH with the help of ferredoxin and NADP reductase enzyme.
Km (Michaelis constant) is the substrate concentration at half Vmax, and it inversely represents enzyme affinity for substrate. Lower Km means higher affinity.
Photorespiration occurs when RuBisCO catalyzes oxygenation of RuBP instead of carboxylation, which happens under high O2 and low CO2 conditions.
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.
The cohesion-tension theory explains water transport in tall trees through cohesive forces between water molecules and tension created by transpiration.
The dorsiventral structure of dicot leaves is primarily established by differential light exposure (adaxial surface receives more direct light, promoting compact palisade development) combined with auxin gradients that influence cell differentiation patterns. The abaxial surface, receiving diffuse light and lower auxin concentration, develops the loosely packed spongy mesophyll with intercellular spaces for gas exchange.
Sieve plate perforations with reduced cell wall material allow efficient translocation of assimilates between sieve tube elements with minimal resistance.