Photosynthesis+Review

1. Why are the palisade mesophyll tightly packed and arranged at right angles to the epidermis? This allows more mesophyll cells with chloroplasts to be exposed to sunlight and thus increase efficiency of photosynthesis in the plant. 2. Why are the guard cells bean-shaped? Since the inner wall of the guard cells is elastic, when the bean-shaped guard cells become turgid, the cells will bend inwards, causing the stomata to open.

3. Name the 3 types of cells in the leaf that contains chloroplasts and 1 type that doesn’t. Palisade mesophyll cells, spongy mesophyll cells and guard cells.

4. Why are stomata found mainly on the lower epidermis of horizontal leaves and not the epidermis? This is to prevent excessive loss of water through transpiration as the stomata on the lower epidermis will be protected from the heat of the sun. 5. Most terrestrial plants have stomata on the lower epidermis yet many aquatic plants like water lilies have stomata only on the upper epidermis. Explain why this is so. Many aquatic plants have stomata on the upper epidermis to allow them to be in contact with air to faciliate gas exchange for processes like photosynthesis and cellular respiration. In addition, the aquatic plants have less need to regulate transpiration since water is abundant and thus they do not have to retain water in the plant. On the other hand, terrestrail plants have stomata on the lower epidermis in order to prevent excessive loss of water through transpiration due to the heat from the sun.

6. What happens if I coat all the leaves of a plant with oil? Explain.

By coating the plants with oil, the stomata of the plants will be blocked and this prevents gas exchange from taking place and also prevents transpiration from taking place.