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plants chap 13/2
| Question | Answer |
|---|---|
| the atm is less humid than air spaces next to stomata. the atm is less humid than air spaces next to stomata. | |
| how is water lost from the air spaces replaced in plants? replaced with water evaporating from CELL WALLS of surrounding (mesophyll cells). | |
| how can plants control rate of transpiration? by changing size of stomatal pores. | |
| How is water lost in mesophyll cells? by evaporation from surfaces to AIR SPACES of leaf. | |
| How is water replaced in mesophyll cells? | water from xylem via the apoplastic or symplastic pathway. |
| In symplast water to mesophyll cell moves coz? | mesophyll cells lose water to air spaces. these cells have lower WP - osmosis occurs from neighbour cells. neighbour cells - have LOW WP. They take in water from their NEIGHBOURS. Estabilishes a wp grad pulls water from xylem across leaf mesophyll. |
| what are the 2 factors, cause water to move up xylem from roots to leaves? | cohesion- tension & root pressure. |
| what does transpirational pull put the xylem under ? | tension - it has neg pressure hence cohesion tension theory. |
| evidence for cohesion tension theory? | DURING DAY transpiration highest- more negative pressure in xylem/ NO MORE TENSION. causes trunk to skrink in diameter. At night less tension in trunk - diameter increases. |
| what haps if xylem vessel broken ? | tree cannot draw water. air enter it CONSTANTLY. continous column oh water broken. water no longer stick together. ( evidence for cohesion tension theory) |
| When would water leak out if xylem vessel broken? If xylem under pressure. | |
| Is transpiration passive or active? why? passive. xylem vessel dead - can' t move water. | |
| because xylem are dead what hap to end walls? they can break down. forms continous unbroken tubes from root. to leaves. good for cohesion - tension theory. | |
| Energy for transpiration comes from? Sun | |
| what does casparin strip prevent? movement of water across cell wall. | |
| HUG a tree finger will meet in day , but not at night. | |
| role of trans: how are leave adapted for photosynthesis? have large surfaceA - to absorb light. stomata - inward diffusion of C02. both result in LOSS OF WATER. | |
| Why is transpiration not neccessary? it helps bring water to leaves - but OSMOSIS THOSE THE SAME. | |
| how does temp affect transpiration? rise in temp: increases kinetic energy of h2o mole. rate of evaporation. increase transpirtion. decreases Airs water potential. (factors that affect transpiration) | |
| (factors that affect transpiration) reduction in temp on transpiration? decreases rate of transpiration. | |
| what does transpirational pull put the xylem under ? tension - it has neg pressure hence cohesion tension theory. | |
| evidence for cohesion tension theory? DURING DAY transpiration highest- more negative pressure in xylem/ NO MORE TENSION. causes trunk to skrink in diameter. At night less tension in trunk - diameter increases. | |
| what haps if xylem vessel broken ? tree cannot draw water. air enter it CONSTANTLY. continous column oh water broken. water no longer stick together. ( evidence for cohesion tension theory) |