Describe how the apparatus should be set up to ensure that valid measurements can be made.
cut (healthy) shoot under water (to stop air entering xylem vessels); 2 cut shoot at a slant (to increase surface area); 3 check apparatus is full of water / is air bubble free / no air locks; 4 insert shoot into apparatus under water / AW
2 of 22
explain why the results gained by using the apparatus are not measures of the actual transpiration rate.
transpiration is the lose of water vapour, apparatus measures rate of uptake, presumes all water uptake is lost, used in photosynthesis
3 of 22
Describe the precautions you would take when setting up and using the apparatus shown in the diagram above in order to get valid readings from which the transpiration rate can be estimated.
cut shoot underwater, cut shoot at slant, no air bubbles in apparatus, dry leaves, allow shoot to acclimatise
4 of 22
State two features of root hair cells which adapt them for water uptake.
large SA:VOL, thin epithelium short diffusion pathway, low water potential
5 of 22
Plants absorb water from the soil via their roots. Describe the pathways and mechanisms by which water passes from the soil to the xylem vessels in the root.
osmosis of water into root, down water potential gradient, WP lowest in xylem due to uptake of minerals and ions, moves via cell wall(apoplast), via cytoplasm(symplast), Casparian ***** blocks apoplast pathway, water crosses membrane.
6 of 22
Describe how two features of xylem vessels adapt them for water transport.
thick wall prevents bursting, develop as a continuous water-filled column allows tension to pull water up, contains lignin allows adhesion
7 of 22
Define the term transpiration.
evaporation of water vapour from plants into the atmosphere via the stomatas down a water potential gradient
8 of 22
Explain how covering of the leafs epidermal hairs helps xerophytes survive in their habitat.
hair traps water vapour, reduces water potential gradient,more humid around leaf, less transpiration, less water loss
9 of 22
Explain how water travels up the stem and into the leaf of a dicotyledonous plant.
in xylem vessels, down a WP gradient, -VE in atmosphere, transpiration sets up gradient, xylem under negative pressure, water molecules cohesive in continuous column, root pressure causes water molecules to travel up stem in xylem, adhesion
10 of 22
Explain how, at different times, the same plant root may be a source or a sink.
source when root turns starch into sugars, sink when root stores starch or uses carbohydrates in respiration
11 of 22
State one way in which root hairs are adapted to increase uptake.
long, thin cell wall, present in large numbers, large SA
12 of 22
State one method used by root hairs to take up nitrate ions.
active transport / diffusion / facilitated diffusion
13 of 22
Outline the process by which water enters the cells of the root from the soil.
low WP inside root, water moves in down a concentration gradient by osmosis, through membrane
14 of 22
give an example in plants of a source and a sink.
source- leaf/storage organ, sink-root/flower
15 of 22
adaptations - swollen steams
water storeage, small SA:VOL, increase diffusion distance, less transpiration
16 of 22
rolled leaves
protects lower epidermis, traps air within leaves, no WP gradient, less transpiration.
17 of 22
leaves to spines
reduced SA, less water loss by transpiration
18 of 22
thick cuticle
waxy waterproof cuticle, increase diffusion distance, reduced water loss
19 of 22
stomata in sunken pits
traps moist air next to leaves, WP gradient reduced, less water loss
20 of 22
hairs on leaves
thick layer of hairs on leaves, on lower epidermis, traps moist air next to leaf, WP gradient reduced.
21 of 22
Explain how transpiration results in the movement of water up a plant stem.
loss of water from mesophyll, more drawn from cytoplasm / cell, cohesion of water molecules, water under hydrostatic pressure, water ‘pulled’ via, symplast/apoplast from xylem
22 of 22
Other cards in this set
Card 2
Front
Describe how the apparatus should be set up to ensure that valid measurements can be made.
Back
cut (healthy) shoot under water (to stop air entering xylem vessels); 2 cut shoot at a slant (to increase surface area); 3 check apparatus is full of water / is air bubble free / no air locks; 4 insert shoot into apparatus under water / AW
Card 3
Front
explain why the results gained by using the apparatus are not measures of the actual transpiration rate.
Back
Card 4
Front
Describe the precautions you would take when setting up and using the apparatus shown in the diagram above in order to get valid readings from which the transpiration rate can be estimated.
Back
Card 5
Front
State two features of root hair cells which adapt them for water uptake.
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