Photosynthesis Flashcards
What are the two stages of photosynthesis known as?
Light-dependent reaction and light-independent reaction (Calvin Cycle)
Where does the light-dependent reaction take place?
Across the thylakoid membrane
What is the role of chlorophyll?
To absorb light
What happens when chlorophyll absorbs light?
Photoionisation - Electrons in the chlorophyll become excited and react with water, splitting it into H+ ions, electrons and oxygen
How is the chloroplast adapted for the light-dependent reaction?
Large surface area due to thylakoid membrane stacked in grana, network of proteins embedded in the membrane, DNA and ribosomes in the stroma to manufacture proteins.
What is produced in the light-dependent reaction?
ATP and reduced NADP.
How is the ATP produced?
Electrons are transferred down the electron transfer chain. Energy from this is used to pump protons across the thylakoid membrane which then move back through ATP synthase proteins embedded int he membrane, generating ATP.
Where does the light-independent reaction take place?
In the stroma
What happens in the light independent reaction?
- Carbon dioxide reacts with ribulose bisphosphate (RuBP) to form two molecules of glycerate 3-phosphate (GP).
- This reaction is catalysed by the enzyme rubisco.
- ATP and reduced NADP from the light-dependent reaction are used to reduce GP to triose phosphate.
- Some of the triose phosphate is used to regenerate RuBP in the Calvin Cycle.
- Some of the triose phosphate is converted into useful organic substances such as glucose, oils etc.
What environmental factors affect the rate of photosynthesis?
Light intensity, carbon dioxide levels, temperature.
What can farmers do to increase photosynthesis?
Artificial lighting and heating, adding extra carbon dioxide.
