Chapter 8: Transport in Plants

Question 1

Xylem

Answer 1

Plant tissue made of dead empty cells joined end to end (lignin)
Transports water and mineral ions
Helps support plant
Lignin: impermeable
One-way transport (upwards)
Travels upwards by transpiration pull

Question 2

Phloem

Answer 2

Plant tissue made of living cells joined end to end
Transports sucrose and amino acids = translocation
2 way transport
Permeable
Has sieve plates

Question 3

Water uptake

Answer 3

Water passes into root hairs by osmosis.
Passes along cortex of root
Moves through spaces in cell walls
Reaches xylem at centre of root
Moves up xylem and enters spongy mesophyll cell
Water -> cell wall -> evaporates -> diffuse through stomata
As more water leaves, more water enters (low conc inside, so high conc outside will enter to reach equilibrium)

Question 4

Transpiration stream

Answer 4

Cohesion: water molecules attract each other, sticking to each other
Adhesion: Water molecules stick inside xylem vessels
Continuous flow of water from roots to leaves
= transpiration stream

Question 5

Transpiration

Answer 5

lose of water vapor from mesophyll surface due to evaporation
exit via stomata

Question 6

transpiration pull

Answer 6

water molecules stick to each other (cohesion), so as water evaporates, more water that sticks to each other will follow

Question 7

Rate of transpiration

Answer 7

humidity (less humidity in surrounding, increase rate)
wind speed (more wind, increase rate)
Light Intensity (increase light intensity, increase rate)
Temperature (Increase temp, increase rate)

Question 8

Measuring level of uptake

Answer 8

Potometer

• container of water
• capillary tube
• rubber tubing
• scale