1. Glucose may be converted into insoluble starch for storage. B2 Photosynthesis: mesophyll, respiration, chlorophyll, chloroplasts, walls, absorbs, carbon dioxide, insoluble, oxygen, storage, glucose, light, water, fats, proteins, oils, nitrate, cellulose Uses of glucose 1. Glucose may be converted into insoluble starch for storage. 2. Plant cells use some glucose during respiration. (glucose + oxygen carbon dioxide + water) 3. Some glucose can be made into fats and oils for storage. 4. Glucose can be used to make cellulose, which strengthens plant cell walls. 5. Glucose can used with nitrate ions from the soil to make proteins. Photosynthesis Plants and algae use light energy to make their own food. The word equation for photosynthesis is… carbon dioxide + water glucose + oxygen The role of chlorophyll Inside the leaf, mesophyll tissue contains many chloroplasts. Chloroplasts contain chlorophyll which absorbs light energy needed for photosynthesis.

1 2 1 2 1 2 2 1 Light intensity Limiting factors B2 Photosynthesis and limiting factors Lighting, carbon dioxide, photosynthesis, limiting factor, temperature, increasing, yield, profit, light, increases, enzymes, Light intensity As the amount of light increases, so does the rate. The limiting factor is light. Here, increasing the amount of light has no affect on the rate. The limiting factor is now carbon dioxide or temperature. 1 2 Limiting factors The rate of photosynthesis may be limited by: 1. Shortage of light 2. Low temperature 3. Shortage of carbon dioxide In reality all 3 factors interact and any one of them can be a limiting factor. Carbon dioxide 1 As the amount of carbon dioxide increases, so does the rate. The limiting factor is carbon dioxide. Here, increasing the amount of carbon dioxide has no affect on the rate. Light or temperature is now the limiting factor. 2 Temperature Greenhouses For optimum plant growth farmers may need to control light, temperature or carbon dioxide. This can be done by using artificial lighting, heaters/ventilation and addition of carbon dioxide. Increases in yield must be balanced against the costs involved if farmers are to make a profit. 1 As temperature increases, so does the rate because photosynthetic enzymes work best in the warmth. Here, the limiting factor is temperature. Most plant enzymes are destroyed at about 45°C. Here, photosynthesis stops and the rate falls to zero. rate of photosynthesis 2 2 1 0oC temperature 45oC