Maas Trans In Plant

Question 1

Describe the cohesion tension theory of water transport in xylem

Answer 1

Water lost from leaf because of transpiration through stomata.
Lower water potential of leaf cells.
Water pulled up xylem creating tension.
Water molecules cohere by hydrogen bonds.
Forming continuous water column.
Adhesion of water molecules to wall of xylem.

Question 2

Prometer measure the rate of water uptake rather than the rate of transpiration. Give 2 reasons why photometer does not truly measure the rate of transpiration.

Answer 2

Water used in condensation reaction.
Water used in photosynthesis.
Water produced in respiration .
Apparatus not sealed.

Question 3

Give 2 precautions the student should have taken when setting up the protometer to obtain reliable measurements off water uptake by plant shoot

Answer 3

Seal joints.
Cut shoot under water.
Cut shoot at a slant.
Dry off leaves.
Insert into apparatus under water.
Ensure no air bubbles are present.
Shut tap.
Note where bubbles is start

Question 4

Explain how pressure is generated inside phloem tube

Answer 4

Sucrose actively transport into phloem.
Lower the water potential.
Water move in phloem by osmosis from xylem

Question 5

Describe how a high pressure is produced in the leaves

Answer 5

Water potential become lower as sugar enter phloem.
Water enter phloem by osmosis.
Increase of water cause increase hydrostatic pressure.