Diagram showing the transverse section through a small part of a leaf

Question 1

cuticle

Answer 1

a waxy, transparent waterproof layer, that is secreted by the upper epidermis. The cuticle stops water from evaporating from the leaf. It is also transparent so it can absorb sunlight easily.

Question 2

chloroplast

Answer 2

a disc-shaped organelle that contains chlorophyll. Where photosynthesis occurs.

Question 3

upper epidermis

Answer 3

a single layer of cells lacking chloroplasts (contains few or no chloroplasts). It protects the inner layers of cells in the leaf. The epidermis is also transparent and very thin to allow maximum light penetration. Secretes the cuticle.

Question 4

palisade mesophyll layer

Answer 4

elongated cells that are arranged like a fence or palisade, they’re tightly packed together in order to increase the surface area for light absorption. Where most photosynthesis takes place. (it’s the main photosynthetic layer)

Question 5

spongy mesophyll layer

Answer 5

rounded cells arranged quite loosely with large air spaces between them that allow carbon dioxide and oxygen to diffuse between them. This layer contains fewer chloroplasts than the palisade layer therefore less photosynthesis occurs.

Question 6

mesophyll layer

Answer 6

makes up the middle layer of the leaf. ‘meso’ means middle and ‘phyll’ means leaf.

Question 7

lower epidermis

Answer 7

A protective layer of closely-fitted cells. The lower epidermis produces a waxy cuticle too in some plant species. The lower epidermis contains pores called stomata that allow carbon dioxide and oxygen to move in and out of the plant respectively.

Question 8

guard cell

Answer 8

sausage/bean shaped cells. The inner wall of each cell is thickened with cellulose. Guard cells, unlike any other cells in the epidermis, do contain chloroplasts.

Question 9

air space

Answer 9

located between the palisade and spongy mesophyll layers. Allows the diffusion of carbon dioxide and oxygen.

Question 10

stoma or stomata

Answer 10

Tiny pores (small holes) surrounded by a pair of guard cells. Each stoma can be open or closed, depending on how turgid its guard cells are. The stomata can open and close to regulate transpiration or allow gas exchange.

Question 11

vein

Answer 11

Plant veins consists of xylem and phloem vessels. These vessels play an essential role in transporting water to the chloroplasts in the mesophyll tissues for photosynthesis. They also transport the sugar
produced by photosynthesis away from these cells to the rest of the plant tissues to be used as an energy source or stored.

Question 12

xylem vessels

Answer 12

Narrow, hollow, dead tubes with lignin arranged end to end to form continuous vessels, responsible for the transport of water and minerals in plants. (doesn’t contain cytoplasm)

Question 13

phloem vessels

Answer 13

The tissue in plants that transports the products of photosynthesis, including sugars and amino acids up and down the plant. (contains cytoplasm)