BIOL1006 Lecture Notes - Lecture 23: Secondary Growth, Water Balance, Vascular Cambium
31 Jul 2018
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Document Summary
Life was bleak until plants colonised the land, where animals moved and plants produces oxygen and provided them food. Living on land requires special adaptations: 13. 75 ya the big bang occurred. Where did land plants come from: heterotrophic protist engulfed a cyanobacterial endosymbiont, evolved from green algae about 450mya. Moving onto land is non-trivial: main challenges, water balance. Land plants - need to protect themselves from drying out (haploid: green algae - surrounded by water which moves passively in and out of cells, cuticle: minimises water loss and protect against uv radiation. Stomata: to efficiently exchange gas and regulate transpiration: roots: extract water and dissolved nutrients from soil, vascular system: transport of water and nutrients to the whole plant, tissue: for structural support, gas exchange. Diversification: to prevent desiccation, one may stay small and live in damp places eg. mosses.
