Biology unit 8

Question 1

Root hair cells

Answer 1

• root hair cells increases surface area, therefore increasing the rate of osmosis/diffusion.
• water moves from the soil into root hair cells, then into the root cortex cells before being transported through phloem vessels around the plant. It’s transported to the mesophyll layer of leaves and evaporates out through stomata into the atmosphere.

Question 2

If water evaporates out of stomata, how does this change the water concentration in the leaf

Answer 2

Causes the water concentration in leaf to decrease
Water moves by osmosis down the water potential gradient from soil to xylem vessels then up the plant to the leaves
we call this process TRANSPIRATION

Question 3

What causes the plants to wilt

Answer 3

If more water evaporates from a plant than can be absorbed from the soil, the plant cells will become flaccid causing the plant to wilt.

Question 4

Water attracts water

Answer 4

Cohesion of water and adhesion to the walls of the xylem vessels allows water to move up the xylem vessels, like water up a straw.

Question 5

Effect of wind speed on transpiration

Answer 5

Higher wind speed = faster evaporation of water out of stomata = faster rate of transpiration.

Question 6

Xylem

Answer 6

Transport of water and mineral ions and support

Question 7

Phloem

Answer 7

Transport of sucrose and amino acids.

Question 8

Translocation definition

Answer 8

The transport of sucrose and amino acids in the phloem, from regions of production to regions of storage or use

Question 9

Transpiration meaning

Answer 9

E the loss of water vapour from plant leaves by evaporation of water at the surfaces of the mesophyll cells followed by diffusion of water vapour through the stomata.