9Bb-6 Leaves and Roots | PDF - Free Printable

1. a) The cell labelled 'X' is called a root hair cell.
b) Its function is to absorb water and mineral ions from the soil.
c) It is adapted to its function because it has a large surface area due to its long, thin shape, which increases the efficiency of absorption.
d) The function of xylem vessels is to transport water and mineral ions from the roots to the rest of the plant.
e) They are adapted to this function because they are long, hollow tubes with no cross walls, allowing water to flow freely. They also have thick, reinforced walls to prevent collapse under tension.

2. a) A: palisade cell, B: spongy cell, C: stomata, D: cuticle, E: epidermis, F: guard cell, G: chloroplast.
b) Water vapour is lost from leaves by the process of evaporation.
c) Arrow Q shows water vapour escaping from the leaf. This happens by the process of transpiration.
d) The swapping of substances like this is called diffusion.

3. Cells of type G (palisade cells) are adapted to their function because they are packed with chloroplasts, which contain chlorophyll, allowing them to absorb light energy for photosynthesis. They are located near the top of the leaf where light is most available.

4. a) Leaves have a large surface area to maximize the amount of light absorbed for photosynthesis.
b) Leaves are thin to allow light to penetrate to the palisade cells, where photosynthesis occurs.
c) Leaves on a plant often grow in such a way that they do not shade one another to ensure each leaf receives adequate sunlight for photosynthesis.
d) Stomata are shut at night to prevent water loss through transpiration, as there is no light for photosynthesis and the plant does not need to take in carbon dioxide.

5. Plants wilt when they lose more water through transpiration than they can absorb from the soil. This can happen due to high temperatures, low humidity, or lack of water in the soil, leading to a loss of turgor pressure in the cells, which causes the plant to droop.