exchange of materials (in plants and gut)
- Created by: Hannahisnotonfire
- Created on: 03-03-17 20:47
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- exchange of materials in plants + gut
- exchange in plants
- stomata in plants allow CO2 to diffuse into leaf from atmosphere
- underneath of leaf- exchange surface- many stomata
- leaves= flat= increase surface area, gas exchange more effective. thin= less distance to diffuse
- walls of cells- exchange surface, Air sacks increase surface area, more chance for CO2 to get in cell
- O2 + water vapour lost through stomata (water vapour lost= evaporation)
- size of stomata controlled by guard cells, Close stomata if plant losing water faster than can replace. Plant wilt without
- water evaporates from cells inside leaf. Escapes by diffusion because a lot inside leaf, less in air. Faster when hot, dry, windy
- water + mineral ions absorbed by plant in roots.
- root hair cells increase surface area of roots= faster absorbsion
- transpiration
- caused by evaporation + diffusion from stomata in leaves
- creates shortage of water in leaf. More drawn up through xylem to replace.
- means more drawn up from roots, so constant transpiration stream (movment of water through plant)
- transpiration= side effect of way leaves adapted for photosynthesis. Have stomata so easy gas exchange. more water on inside of plant than outside in air. water escapes through stomata.
- plant could dehydrate if rate of evaporation greater than water uptake by roots.
- guard cells close= prevent excess water loss. wilting of whole plant= prevent excess water loss. leaves collapse+ hang down= smaller surface area.
- exchange in gut
- food digested= small, soluble molecules. in small intestine solutes absorbed by blood
- villi line inner surface of small intestine- exchange surface for food molecules.
- Villi are efficient exchange surfaces foe aborption of soluble products of digestion by diffusion or active transport.
- villi- increase surface area so digested food is absorbed more quickly in blood.
- thin walls and many capillaries close to wall, good blood supply assists absorption
- soluble products absorbed by active transport/ digestion
- thin walls and many capillaries close to wall, good blood supply assists absorption
- exchange in plants
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