1. PHOTOSYNTHESIS
IB SL Biology

2. STAGES OF PHOTOSYNTHESIS
Light dependent stage
Light independent stage (Calvin Cycle)

3. ABSORPTION SPECTRUM
Light consists of different wavelengths and forms part of the electromagnetic spectrum.

4. ABSORPTION SPECTRUM Pigments absorb some colours and reflect others.
Leaves are green as they contain chlorophyll.
Leaves therefore do not use green light

5. ABSORPTION SPECTRUM
The graph shows the wavelengths of light used by plants in photosynthesis.
This may vary between different plants as they contain different photosynthetic pigments

6. PHOTOSYNTHESIS Hydrogen
PHOTOLYSIS
The light independent stage – Light is used to split water (PHOTOLYSIS)
Oxygen is a waste product – hydrogen is used in carbon fixation
ATP is also produced and is used to fix carbon dioxide to form carbohydrate (glucose)

7. PHOTOSYNTHESIS Hydrogen
PHOTOLYSIS
Carbon dioxide is fixed in the light-independent stage.
This produces carbohydrate, initially in the form of glucose.
Glucose is only one of a number of products that can be produced by photosynthesis

8. Use of glucose GLUCOSE Cellulose for cell walls
Amino acids to make proteins including enzymes
Fats and oils for storage in seeds
Converted to sucrose for translocation in the phloem and storage in fruit
Used immediately for respiration
Stored as starch in leaves and tubers

9. Summary

10. Factors affecting the rate of Photosynthesis

11. Rate limiting factors E D C B A