Transport in Plants

Question 1

Describe how guard cells are adapted to their role:

Answer 1

• They have unevenly thickened walls
• able to change shape
• transport proteins in the plasma membrane
• the presence of chloroplast to provide ATP

Question 2

Name a part other than the leaves that which water may be lost:

Answer 2

• epidermis/ cuticles

Question 3

What happens if all the water is lost from the leaf cells is not replaced?

Answer 3

The plant will lose turgidity and may even will.

Question 4

there was an experiment where an isolated companion cell was treated with cyanide which stops aerobic respiration. what conclusion can be drawn from it preventing the PH change from occurring?

Answer 4

• Active transport is involved in the movement of ions. Cyanide prevents this as active transport requires energy from ATP.

Question 5

What you might see from a companion cell using an electron microscope:

Answer 5

• large mitochondria

- plasmodesmata in the companion cells

Question 6

Aphid mouthpart was used to take samples of sugar solutions and the number of drips was counted as well as the temperature. Explain the results:

Answer 6

• At low temperatures, there is not enough KE therefore there is little ATP. The less active transport or less movement of sugars into sieve tube elements. Fewer movements so, therefore, low hydrostatic pressure.
• As temp increases, the molecules have more KE so there is more respiration so ATP is made. more loading of sucrose into sieve tube elements and more hydrostatic pressure is created.
• at high temperatures, the plant enzymes/ proteins are denatured.

Question 7

describe the xerophytic plants’ adaptations and how it reduces water loss:

Answer 7

• they have a thick waxy cuticle and therefore this means its waterproof
• rolls up or bends during windy times or hot temperatures. This traps water vapors and reduces transpiration and the surface area of plants. this reduces the surface area of the plant.

Question 8

two adaptations of sieve tube elements that enable mass flow:

Answer 8

• they have pores in the ends walls and they have no nucleus and no organelles.

Question 9

features that enable the steam to pass from the xylem:

Answer 9

• lignified bordered pits

- no end walls and no living compartments

Question 10

how transpiration contributes to the mechanism of water transport up the stem:

Answer 10

• water loss from the leaves is replaced via the symplast pathways and the apoplast pathway. The loss of water causes a low hydrostatic pressure at the top of the leaves which creates a pressure gradient.
  This is pulled up via tension.

Question 11

two adaptations of leaves that reduce evaporation:

Answer 11

• thick waxy cuticle layer
• the leaf is folded to reduce water loss
• it has hair which traps water vapour