Organisation in Plants

Question 1

Epidermal tissue

Answer 1

Covers the upper and lower surface of the leaf and secretes a waxy layer so that water runs off of the leaf and into the soil below. Also reduces evaporation.

Question 2

Palisade mesophyll

Answer 2

The upper mesophyll layer is covered in palisade cells. Contain lots of chloroplasts to maximize the amount of sunlight absorbed and are rectangular shaped.

Question 3

Spongy mesophyll

Answer 3

A layer of cells below palisade cells that can’t squeeze as tightly so air pockets are present. These air pockets allow CO2 and water vapour to enter as many cells as possible in the leaf as there is a bigger surface area where the mesophyll cell membranes meet these two gases.

Question 4

Upper epidermal tissue

Answer 4

The cells here are also transparent to allow sunlight through to the cells below.

Question 5

Lower epidermal tissue

Answer 5

Covered in stomata. Two guard cells for every stoma. Allow CO2 to diffuse into the leaf and O2 out. The stoma open and close in relation to water availability.

Question 6

Phloem

Answer 6

A tube (vein) that transports dissolved tissues around the plant by translocation.

Question 7

Xylem

Answer 7

A tube that carries water up from the soil to the leaf (by transpiration) and water diffuses from the xylem by osmosis and into the cells in the leaf.