PHOTOSYNTHESIS IB SL Biology
STAGES OF PHOTOSYNTHESIS Light dependent stage Light independent stage (Calvin Cycle)
ABSORPTION SPECTRUM Light consists of different wavelengths and forms part of the electromagnetic spectrum.
ABSORPTION SPECTRUM Pigments absorb some colours and reflect others. Leaves are green as they contain chlorophyll. Leaves therefore do not use green light
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
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)
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
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
Summary
Factors affecting the rate of Photosynthesis
Rate limiting factors E D C B A