Topic 3: The Chemistry of Life 3.8 Photosynthesis

Assessment Statements State that photosynthesis involves the conversion of light energy into chemical energy State that light from the Sun is composed of a range of wavelengths (colours) State that chororphyll is the main photosynthetic pigment Outline the differences in absorption of red, blue and green light by chlorophyll State that light energy is used to produce ATP, and to split water molecules (photolysis) to form oxygen and hydrogen State that ATP and hydrogen (derived from the photolysis of water) are used to fix carbon dioxide to make organic moleules Explain that the rate of photosynthesis can be measured directly by the production of oxygen or the uptake of carbon dioxide, or indirectly by an increase in biomass Outline the effects of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis

3.8.1 State that photosynthesis involves the conversion of light energy into chemical energy 6CO 2 + 6H 2 0C 6 H 12 O 6 + 6O 2 inorganic compounds organic compound sunlight chlorophyll

3.8.2 State that light from the Sun is composed of a range of wavelengths (colours) Chlorophyll absorbs light Many other photosynthetic pigments in chloroplasts ROY G. BIV

3.8.3 State that chlororphyll is the main photosynthetic pigment Outline the differences in absorption of red, blue and green light by chlorophyll Chlorophyll is a green pigment. What part of the electromagnetic spectrum does it absorb?

3.8.5 State that light energy is used to produce ATP, and to split water molecules (photolysis) to form oxygen and hydrogen Light dependent reactions: light energy  chemical energy (ATP) Photolysis: light energy used to split water into oxygen and hydrogen

3.8.6 State that ATP and hydrogen (derived from the photolysis of water) are used to fix carbon dioxide to make organic molecules Light independent reactions: ATP and hydrogen used to convert inorganic molecules into organic molecules (fixation) CO 2 and H 2 O are fixed into glucose with O 2 as a by-product What happens to the glucose made?

3.8.7 Explain that the rate of photosynthesis can be measured directly by the production of oxygen or the uptake of carbon dioxide, or indirectly by an increase in biomass Correction for cell respiration must be made if measuring oxygen production or carbon dioxide uptake Biomass: increase/decrease can be attributed to multiple factors and not just photosynthesis

3.8.8 Outline the effects of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis