Plant cell wall, chloroplast, xylem/phloem, stomata, meristems, phytohormones.
Plant Biology
Plant cell wall
Cellulose-hemicellulose-pectin composite (primary wall) + lignin (secondary wall). Mechanical support, turgor resistance, pathogen defence;…
Xylem and phloem
Vascular tissues. Xylem: dead tracheary elements conducting water + minerals upward by cohesion-tension (transpiration stream). Phloem:…
Stomata
Adjustable epidermal pore flanked by two guard cells. Opening allows CO2 influx + H2O vapour efflux. Regulated by light (blue), CO2, ABA.…
Meristem
Region of undifferentiated dividing plant cells. Apical meristems (SAM, RAM) drive primary growth; lateral meristems (vascular + cork…
Photosynthesis (C3)
Light-driven CO2 fixation: light reactions in thylakoids (photosystems → NADPH + ATP) + Calvin cycle in stroma (rubisco fixes CO2 to 3-PGA…
Auxin (IAA)
Indole-3-acetic acid — polar-transported plant hormone driving cell elongation, apical dominance, tropisms, vascular differentiation. Polar…
Biological nitrogen fixation
Conversion of N2 to NH3 by nitrogenase (MoFe protein + Fe protein), ~16 ATP per N2 reduced. Oxygen-labile. Found in diazotrophs…
C3/C4/CAM photosynthesis
C3 direct fixation (most plants); C4 Hatch-Slack concentrates CO2 via PEP carboxylase (maize, sugarcane) reducing photorespiration; CAM…
Plant hormones overview
Auxin (growth), gibberellin (stem elongation), cytokinin (cell division), abscisic acid (stress), ethylene (fruit ripening),…
Plant pathogen response
Two-tier immunity: PAMP-triggered (PTI) via LRR receptor kinases; effector-triggered (ETI) via intracellular NLR proteins. Systemic…