Cohesion-tension theory explains that water is pulled upward due to transpirational pull creating negative pressure in xylem.

Rhizobium bacteria in root nodules of legumes fix atmospheric nitrogen into ammonia through nitrogenase enzyme.

Physiological wilting occurs when transpiration rate exceeds water absorption rate, though soil moisture is sufficient.

Double fertilization: one sperm fuses with egg nucleus (embryo), other fuses with polar nuclei (endosperm - 3n).

C4 plants have higher photosynthetic efficiency (~60%) compared to C3 plants (~30%) because they concentrate CO2 around RuBisCO, reducing photorespiration. This adaptation makes them suited for hot climates - important agricultural knowledge.

Protons accumulate in the thylakoid lumen (pH 4-5) due to water photolysis and electron transport, creating a chemiosmotic gradient for ATP synthesis. The stroma maintains pH ~8. This proton gradient is essential for understanding light reactions.

Photosystem I is an integral membrane protein complex with multiple transmembrane domains, making it hydrophobic. Rubisco is soluble, while ferredoxin and plastocyanin are soluble electron carriers. This biochemical distinction is important for understanding photosynthetic mechanisms.

Stomatal conductance (gs) is the rate of gas diffusion through stomata, dependent on aperture width and inversely on distance (g = A/L).

PSII catalyzes photolysis of water at the oxygen-evolving complex, transferring electrons to plastoquinone in the thylakoid membrane.

Water photolysis occurs in the thylakoid lumen as part of Photosystem II, releasing O2, H+, and electrons that drive the electron transport chain.