B3c

B3c

1. Water enters a plant through root hairs.

2. Carbon dioxide enters, and oxygen leaves, a plant through stomata

3. Broad leaves provide a large surface area. This makes photosynthesis more efficient as there is lots of space for the light to strike the leaf, so allows a large amount of light energy to be absorbed

4. Thin leaves provided a short distance for gases (such as CO2) to diffuse quickly from the atmosphere to the cells that are carrying out photosynthesis

5. Leaves contain a number of pigments (chlorophyll a and b, carotene and xanophyll) to absorb light from different parts of the spectrum. This means that many wavelengths of light can be absorbed, allowing the leaf to use the maximum amount of energy possible from the sunlight

6. Leaves have a network of vascular bundles for support and transport. This makes photosynthesis more efficient as it provides a source of water and carry away the products of photosynthesis for storage

7. Guard cells open and close the stomata. This makes photosynthesis more efficient as the stomata can open when CO2 is required (and can prevent water escaping when there is little water available)

8. The epidermis is transparent to allow light to pass through it

9. The palisade layer contains most of the chloroplasts and absorbs the most light. This allows gases to diffuse easily from the stomata reach all the cells in the leaf

10. Air spaces in the spongy mesophyll allow diffusion between stomata and photosynthesising cells

11. The leaf’s internal surface area to volume ratio is very large allowing efficient diffusion of substances into/out of cells

12. The palisade cells mainly have chloroplasts down the side which allows some light to reach past this layer to the spongy mesophyll cells

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