3.1.3: Transport In Plants

Question 1

What is the apoplast pathway?

Answer 1

The apoplast pathway is through the cell walls where water can enter and move due to cohesive forces.

Question 2

What does the cohesion-tension theory explain?

Answer 2

The cohesion-tension theory explains how water moves up a plant in the xylem from the roots to the leaves against gravity.

Question 3

What is cohesion in the context of water molecules?

Answer 3

Cohesion is the attraction between water molecules due to hydrogen bonds, allowing them to stick together.

Question 4

What role does tension play in the transpiration stream?

Answer 4

Tension is created when water evaporates from stomata, pulling water up the xylem and causing it to narrow.

Question 5

How does the diameter of xylem change according to transpiration rates?

Answer 5

The diameter of xylem changes as water evaporates, measurable by the tension created in the xylem.

Question 6

What is adhesion in relation to water and xylem walls?

Answer 6

Adhesion refers to water sticking to other molecules, forming hydrogen bonds with xylem walls.

Question 7

What happens to capillarity action as the xylem narrows?

Answer 7

The narrower the xylem, the greater the impact of capillarity action, allowing better water transport.

Question 8

Fill in the blank: Water travels up the xylem as a continuous _______.

Answer 8

[transpiration stream]

Question 9

True or False: Water molecules have a slight positive charge on the oxygen atom.

Answer 9

False

Question 10

What is the significance of the straw model in understanding water transport?

Answer 10

The straw model demonstrates that the narrower the straw, the less pull is required to draw up the liquid due to increased adhesion.