Photosynthesis

1. Photosynthesis Make sure you revise: • What Photosynthesis is • Equation for Photosynthesis • Factors that effect the rate of Photosynthesis • Use of glucose from Photosynthesis • Healthy plant growth (nitrates ions)

2. Photosynthesis Photosynthesis can be summarised by the equation: Carbon dioxide + water (+ light energy)  Glucose + Oxygen • Photosynthesis is when green plants use light energy to make their own food . During photosynthesis: - light energy is absorbed by chlorophyll (a green substance found in chloroplasts of some plant cells. - light energy converts carbon dioxideandwater into sugar (glucose). - oxygen is released as a by-product.

3. What factors affect the rate of Photosynthesis

4. Limiting carbon dioxide levels • Increasing carbon dioxide levels increases the rate of photosynthesisup to a point. • Eventually one of the other factors (temperature and light) becomes limiting • If there is too little carbon dioxide the rate will slow down. • Carbon dioxide maybe limited in an enclosed space eg, a greenhouse on a sunny day or in a rapidly photosynthesising rain forest

5. Limiting light intensity • Increasing light intensity increases the rate of photosynthesis up to a point • When a certain light intensity is reached the rate of photosynthesis stays constant • Eventually one of the other factors becomes limiting

6. Limiting temperature • If it is cold then enzymes do not work effectively slowing down the rate. • The rate of photosynthesis increases steadily with a rise in temperature up to a certain point (35-40ºC = optimum temp) • After this the enzymes are destroyed and the reaction stops completely.

8. Healthy plant growth • Plant roots absorb mineral ions • needed for healthy growth • For healthy growth plants need • mineral ions including • Nitrates and • Magnesium

9. Photosynthesis quiz