ETIABO: Photosynthesis - Light-independent Reaction Flashcards
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 to useful organic substances. Idenifying environmental factors and agricultural practices to overcome this
Where does the LIR occur?
Stroma
What are the two stages of photosynthesis?
- Light dependent reaction
- Light independent reaction
What are the two products needed for the light-independent reaction to occur?
- ATP
- 2x Reduced NADP (aka NADPH)
What is the Calvin cycle another name for?
Light-independent reaction
Where does the LIR occur in a chloroplast?
Stroma
What are the three main substances involved in the LIR?
- Ribulose biphosphate (RuBP)
- Glycerate 3 phosphate (GP)
- Triose phosphate (TP)
What enzyme catalyses the conversion of RuBP into GP?
Rubisco
When carbon dioxide enters the stroma it reacts with ______ to form __ _____ molecules, catalysed by rubisco.
Ribulose biphosphate (RuBP)
Glycerate 3 phosphate (GP)
How many carbons does RuBP have?
5
How many carbons does 1 GP molecule have?
3
Carbon dioxide reacts with RuBP in the stroma to form what?
Two GP molecules.
How does GP become TP?
- Two molecules of NADPH gives a proton each to a GP molecule. This forms two NADP molecules and two GP molecules.
- ATP is used
What is the difference between GP and TP?
GP has a negatively charged oxygen molecule
TP has a hydrogen molecule
This is why NADPH is needed- NADPH gives the proton (H) to GP, so GP is reduced and can form TP.
ATP is needed for the reduction reaction of GP being converted into TP. Where does this ATP come from?
Product of the LDR.
How does ATP provide energy for processes?
Hydolyses into ADP + Pi
What molecules are produced from the LIR that are needed for the LDR?
- ADP
- Pi
- NADP
Most triose phosphate goes on to produce ______, little of it goes on to produce _______ ________.
Ribulose biphosphate (RuBP)
Organic subtances
A little bit of the triose phosphate made goes on to produce organic substances. What three organic substances are made?
- Glucose
- Amino acids
- Glycerol
Glucose is one of the 3 organic substances made by triose phosphate. Why is glucose produced?
Used in respiration
Amino acids are one of the 3 organic substances made by triose phosphate. Why are amino acids produced?
Used to create proteins
Glycerol is one of the 3 organic substances made by triose phosphate. Why is glycerol produced?
Used to form triglycerides- good energy storage and water source
Most of the triose phosphate molecules formed are used to make ribulose biphosphate. This requires energy in the form of _____.
ATP
What are the three main limiting factors for photosynthesis?
Light
Carbon dioxide
Temperature
What are the end products produced by the LIR?
- ADP
- Pi
- NADP
- Ribulose biphosphate
- Organic subtances: glucose, amino acids, glycerol
What impact does increased light intensity have on the rate of photosynthesis? Why?
Increases the rate of photosynthesis overall.
- Light is needed for photoionisation and photolysis. More light means these processes can happen at a greater rate.
- These processes produce ATP and NADPH, allowing for the LIR to happen at a greater rate.
- Will increase the rate of photosynthesis until a limiting factor occurs.
Why is carbon dioxide needed?
Used in the conversion of RuBP into GP
What impact does increased carbon dioxide concentration have on the rate of photosynthesis? Why?
Increases the rate of photosynthesis overall.
- Carbon dioxide is needed in the light-dependent reaction to convert RuBP into GP.
- Will increase the rate of photosynthesis until a limiting factor occurs.
What impact does increased temperature have on the rate of photosynthesis? Why?
Increases the rate of photosynthesis up to optimum temperature, decreases rate of photosynthesis when temp is too high.
- Higher temperatures provides more kinetic energy to molecules, allowing enzyme rubisco to catalyse at a greater rate.
- Too high temperatures will mean enzyme rubisco is denatured, decreasing the rate of reactions in the LIR.
- Too high temperatures will also negatively impact the thylakoid membrane e.g damage chlorophyll-containing proteins in the membrane, preventing the normal functioning of the ETC, decreasing the rate of reactioons in the LDR.
