- Photosynthesis word equation -
- Carbon dioxide + water -(light energy)-> glucose + oxygen
- Glucose is a large molecule and contains energy in its bonds that can be used for growth.
- Chlorophyll (found in chloroplasts) absorbs light energy, which is used to convert carbon dioxide and water into glucose.
- Green and white leaves are called variagated leaves - only the green parts contain chlorophyll.
- Green algae contains chloroplasts and can photosynthesise.
- To test if a plant is photosynthesising is to test it for starch - Excess sugar produced during photosynthesis is stored as insoluble starch and will show as blue-black.
- Before iodine is added to leaves they are plunged into boiling and decolourised by heating in ethanol.
- You can check that oxygen is produced in photosynthesis by collecting and testing it it with a glowing splint.
- The rate of photosynthesis is affected by -
- light intensity
- carbon dioxide availability
- water availability
- It is limited by
- low temperature
- shortage of carbon dioxide
- shortage of light
- You can increase an individual limiting factor but the rate of photosynthesis will always be limited by another limiting factor.
- Increasing the temperature of plants beyond the optimum causes the enzymes that cause photosynthesis to denature, which stops photosynthesis.
- Light intensity and level of carbon dioxide interact to affect the rate of photosynthesis.
- They change throughout the day so any one of them may be the limiting factor.
- Carbon dioxide can be a limiting factor when plants grow densely together as forests or crops.
- Stored carbohydrates in plants such as potato or corn helps the plants to survive over the winter and supports new growth in the spring.