Leaves and photosynthesis

Question 1

How is the epidermis adapted for photosynthesis?

Answer 1

The outer epidermis lacks chloroplasts and so is transparent; there are no barriers to the entry of light.

Question 2

How is the palisade adapted for photosynthesis?

Answer 2

The upper palisade layer contains most of the leaves’ chloroplast, as they will receive most of the light.

Question 3

How is the spongy mesophyll cells adapted for photosynthesis?

Answer 3

• The spongy mesophyll cells are loosely spaced so that diffusion of gases between cells and the outside atmosphere can take place.
• The arrangement of mesophyll cell creates a large surface area/volume ratio so that large amounts of gas can enter and exit the cells.

Question 4

How is the structure of leaves adapted to efficiently photosynthesis?

Answer 4

• They are usually broad so that they have a large surface area to get as much light as possible.
• They are usually thin so that gases can diffuse through easily and light can get to all cells.
• They have a network of vascular bundles (veins) for support and transport of chemicals such as water and glucose.

Question 5

Leaves adaptation for photosynthesis: stomata

Answer 5

They have specialised guard cells which control the opening and closing of stomata therefore regulating the flow of carbon dioxide and oxygen as well as water loss.

Question 6

What do leaves contain that make photosynthesis efficient?

Answer 6

• They contain chlorophyll and other pigments so that they can use light from a broad range of the light spectrum.
• By having many pigment (chlorophyll a and b, carotene and xanthophylls) the plant cells can maximise the use of the Sun’s energy. Each pigment absorbs light of different wavelengths