Botany: Plant Structure, Physiology and Diversity
Core concepts
Know plant tissues: meristematic, parenchyma, collenchyma, sclerenchyma, xylem, phloem. Know root, stem, and leaf structure and modifications. Understand transport: water and minerals via xylem (transpiration pull, cohesion-tension), sugars via phloem (translocation). Know photosynthesis and respiration at the plant level, stomatal regulation, and mineral nutrition. Know plant hormones (auxin, gibberellin, cytokinin, abscisic acid, ethylene). Know diversity: algae, mosses, ferns, gymnosperms, angiosperms, and their reproductive adaptations.
Traps
Xylem transports water upward; phloem transports sugars both directions. Transpiration is water loss, not water uptake. Mosses lack vascular tissue and need water for reproduction. Ferns have vascular tissue but need water for fertilization. Gymnosperms have naked seeds; angiosperms have enclosed seeds and flowers. Auxin promotes growth but high concentrations can inhibit. Do not confuse stomatal opening (turgid guard cells) with closing (flaccid).
Worked example / rule of thumb
Rule of thumb: "xylem up, phloem around; water needs no ATP, sugar does." Worked example: girdling a stem removes phloem and blocks sugar transport, so roots starve while leaves keep receiving water through intact xylem. If a question asks how water rises in tall trees, answer cohesion-tension driven by transpiration.