What is transpiration?

Question 1

define transpiration

Answer 1

transpiration is 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

Question 2

what happens to replace the water lost in transpiration

Answer 2

water travels up xylem from the roots into the leaves of the plant to replace the water that has been lost due to transpiration

Question 3

how does lignin affect the xylem

Answer 3

a substance called lignin is deposited in the cell walls which causes the xylem cells to die

Question 4

what happens after xylem cells die

Answer 4

these cells then become hollow (they lose all their organelles and cytoplasm) and join end-to-end to form a continuous tube for water and mineral ions to travel through from the roots

Question 5

what does lignin do

Answer 5

lignin strengthens the plant to help it withstand the pressure of the water movement

Question 6

explain the movement in xylem

Answer 6

movement in xylem only takes place in one direction - from roots to leaves

Question 7

how does xylem movement differ to phloem movement

Answer 7

xylem movement only takes place in one direction whereas phloem movement takes place in different directions