- Plants make their own food by photosynthesis.
- The food that plants make through photosynthesis is a type of sugar called glucose.
- During photosynthesis, plants use carbon dioxide and water to produce glucose and oxygen, using sunlight as energy.
- Sunlight is absorbed by green pigments called chlorophyll, which is located in chloroplasts of plant cells.
Structure of Leaves
Most of the photosynthesis happens at leaves of plants, so structure of leaves are adapted for photosynthesis.
How the structures of leaves🌿 are adapted for photosynthesis:
- Wide and flat leaves: Increases surface area to capture as much light as possible
- Thin leaves: Carbon dioxide can reach cells easily
- Network of veins in leaves: Transports water to leaves and glucose away from leaves
- Waxy cuticle: Prevents water loss through evaporation while still absorbing sunlight
- Thin and transparent epidermis: Allows more light to reach palisade mesophyll, where much of photosynthesis happens in leaves
- Numerous chloroplasts in palisade mesophyll: Increases the rate of photosynthesis with many chlorophylls capturing a lot of sunlight
- Air spaces in spongy mesophyll: Allows carbon dioxide and oxygen to diffuse in and out of leaves faster
- Guard cells and stomata: Opening stoma by controlling guard cells allows carbon dioxide to enter leaves and oxygen to go out of leaves
Factors that Affect the Rate of Photosynthesis
- Light intensity: As light intensity increases, the rate of photosynthesis increases until other factors start to limit the rate of photosynthesis.
- Carbon dioxide concentration: As concentration of carbon dioxide increases, the rate of photosynthesis increases until other factors start to limit the rate of photosynthesis.
- Temperature: Photosynthesis is controlled by enzymes. To a certain temperature, the rate of photosynthesis increases as temperature increases. However, when the temperature gets too high, enzymes denature and cannot function anymore, so the rate of photosynthesis drops.