Question 17N.2.HL.TZ0.b
| Date | November 2017 | Marks available | [Maximum mark: 8] | Reference code | 17N.2.HL.TZ0.b |
| Level | HL | Paper | 2 | Time zone | TZ0 |
| Command term | Explain | Question number | b | Adapted from | N/A |
Plants have widespread influences, from food chains to climate change.
Explain the process of water uptake and transport by plants.
[8]
a. roots/root hairs absorb water
b. water is absorbed by osmosis
c. solute concentration inside the root is higher/water potential is lower «than in the soil»
d. due to active transport of ions/minerals into the root
e. transport of water in xylem vessels
f. flow/stream of water from roots to leaves
g. water movement in xylem due to pulling force/transpiration pull/suction/negative pressure potential
h. cohesion/hydrogen bonds between water molecules «allows water to be pulled up in xylem»
i. transpiration in leaves generates tension/pulling forces/suction
j. evaporation of water from «leaf» cell walls
k. adhesion of water to «leaf» cell walls/cellulose creates tension «forces»
Not adhesion to xylem walls in mpk and the adhesion must be linked to creating tension
l. lignin in xylem walls/thickened xylem walls prevent collapse/resist tension
m. «movement of water in xylem is a» passive process
[Max 8 Marks]
