Photosynthesis Ch. 11 Flashcards
Give some examples of how the structure of a leaf helps photosynthesis.
Large surface area to absorb light.
Transparent cuticle lets light pass through.
Lots of stomata allows for gas exchange.
Xylem brings water, phloem carries away glucose.
Mesophyll cells are packed long and narrow and contains lots of chlorophyll.
`What is the general equation for photosynthesis?
6CO2 + 6H2O = C6H12O6 +6O2
What’s the first reaction of photosynthesis?
Light- Dependen Reaction
Where does the light-dependant reaction occur?
In the thylakoid in the chloroplast
Whats in the thylakoid?
Chlorophyll
What is the first stage of the light - dependant reaction?
Photoionisation
What happens in photoionisation?
Chlorophyll molecule absorbs light and excites a pair of electrons so they leave the molecule.
What happens to the electrons from the chlorophyll?
Electrons pass along the electron transfer chain
Describe how in the light- dependent reaction of photosynthesis, light energy generates ATP?
- Light excites a pair of electrons in chlorophyll; - Electrons pass down electron transfer chain - In the thylakoid - Electrons reduce carriers - Energy released - ATP generated from ADP and Pi
What coenzymes are used in photosynthesis?
NADPH
How is ATP made in photosynthesis?
By oxidative phosphorylation.
From where to where are H+ ions pumped to in chloroplast?
Across the thylakoid membrane, from stroma to the thylakoid.
What is photolysis?
When water breaks down into H+ ions, electrong and oxygen using light energy.
Why is photolysis important?
The electrons are used to replace those lost in Photoinoisation in the chlorophyll molecule. The H+ contributes to the gradient.
What acts as the final electron acceptor?
NAD. NAD gets reduced to NADH.
What is produced in the Light dependent reaction?
ATP, NADH and Oxygen
Where does the light independent reaction occur?
In the stroma
What is produced in the light independent reaction?
Glucose
What happens in the light independent reaction?
1) CO2 combines with RuBP.
2) RuBP is catalysed by Rubisco enzyme and produces 2x GP.
3) Each GP is reduced to TP using ATP and NADPH
4) 2 TP are produces in each cycle. 2 TPs are required to form glucose and 10 are required to reform RuBP.
What is TP ?
triose phosphate
How many TP needed to form glucose?
2
How many TPs needed to reform RuBP?
10
What is the light independent reaction dependent on?
ATP and NADPH produced from the light dependent stage.
What would happen to the concentration of RuBP and GP, if CO2 concentration suddenly decreased?
RuBP concentration increases and then decreases because RuBP is not being combined with CO2 and some TP is still regenerating RuBP. When all the TP runs out because there is not GP being produced the concentration decreases. GP decreases straight away as CO2 no longer combines with RuBP to produce GP.
Where is RuBP found?
In the Stroma.
Why does increasing oxygen concentration decrease CO2 absorption?
Oxygen acts as a competitive inhibitor for the active site of Rubisco enzyme.
What happens to carriers in the electron transfer chain?
They get reduced.
What happens if one electron carrier doesn’t work
The next carriers are not reduced
Why does changing the CO2 concentration effect the rate of transpiration in plants that are watered than in dry?
In dry the stomata is partially closed due to the less turgid guard cells.
Describe the part played by chlorophyll in photosynthesis?
light (energy) absorbed by chlorophyll;
electrons are excited
ATP formed;
What’s GP?
glycerate 3-phosphate
