Photosynthesis Flashcards
What is the granum
The stack of thylakoids
What is a thylakoid
A single part of the granum stack
What is the stroma
Inner area filled with enzymes
Why do chloroplasts have multiple pigments?
There’s different wavelengths so more pigment means more wavelengths are absorbed
What is a photo system
A group of pigments that work together to absorb as much wavelength as possible. They’re embedded into the thylakoid membrane
Describe the light dependent reaction
Light hits photo system
Chlorophyll molecule gets excited
Electrons leave molecule and move along electron transport chain
Energy lost and used to transport protons from stroma into thylakoid membrane space
NADP is final electron acceptor and becomes reduced
Protons activate ATP synthase
ADP + PI -> ATP
What is photolysis
H2O split into electrons and protons
Why does photolysis occur in the light dependent reaction
Replaces electrons lost when electrons leave photosystem
So reduces photosystem
What is photophosphorylation
Phosphorylation in the presence of light
Where is ATP made during the light dependent reaction
In the stroma
What adaptations do leaves have
Large SA collect as much light as possible
Stomata open and close as light intensity changes
Packed mesophyll so sunlight hits chloroplasts
Thin so short diffusion pathway
What is the word equation for photosynthesis
Co2 + water -> glucose + oxygen
What is the photosynthesis equation (not words)
6 Co2 + 6 H2O
->
C6H12O6 + 6 o2
What part of the light dependent reaction is cyclic photophosphorylation and how
Photosystem I
Electrons rejoin ETC allowing more energy to make ATP
What are the products of the light dependent reaction
ATP and NADPH
What is the light independent reaction also known as
The Calvin cycle
How many RUBP are produced for every 1 molecule of glucose made
6
What products are required for the Calvin cycle
ATP and NADPH
Why is the stroma the best place for the light independent reaction to take place
It has all the enzymes required for the cycle
Where does the light independent reaction take place
In the stroma
Describe the Calvin cycle
Co2 comes in RUBP joins co2 because of enzyme rubisco 6 carbon compound unstable so breaks into 2 3 carbon compounds = GP GP reduced by ATP and NADPH 2 TP molecules form Cycle happens 6 times then Carbon comes away to make glucose Spare TP used to regenerate RUBP
What is glucose from the light independent reaction used for
Make starch, lipids, cellulose, amino acids etc. Basically all organic molecules plant needs
In evidence experiment for Calvin cycle, why is co2 supplied to algae radioactively labelled
Allows the substances to be identified as CO2 in all of them
In evidence experiment of Calvin cycle, how might the hot methanol stop further chemical reactions taking place?
The high temperature and methanol denature the enzyme that catalyse reactions
In evidence experiment of Calvin cycle, why is hot alcohol used
Hot temperature denature enzyme that catalyse the reaction
In evidence experiment of Calvin cycle, why is a rapid action tap used
Allows small sample
To quickly be released
What are the limiting factors of photosynthesis
Lack of light
Lack of co2
Temperature (too hot or too cold)
In a photosynthesis experiment, why must it be airtight?
To stop the co2 bubbles from going into the atmosphere instead of being counted
How does different light intensities affect photosynthesis
Light = more co2 so more photosynthesis
No light = respiration not photosynthesis
What is the natural level of co2
0.03%
What happens in photosynthesis if the temperature is too cold
There is not enough kinetic energy
What happens in photosynthesis if the temperature is too hot
Bonds break Shape not held Active site lost No enzyme-substrate complex Enzyme denatured
Explain what’s happens during the light-independent reaction
Co2 combines with RUBP GP produced GP reduced to TP Using NADPH and energy from ATP TP converted to organic substances
Name parts of a chloroplast
Double membrane Stroma Thylakoid Granum Inter-granal thylakoid
Explain why the rate of photosynthesis increases when the percentage of light absorbed increases
Light provides energy for light dependent reactions
Why is green light wavelength not absorbed
Green plants reflect green light
Describe the part played by chlorophyll in photosynthesis
Light energy is absorbed by chlorophyll
Electrons excited
ATP formed
Why might hydrogen sulphide be used in photosynthesis
Provide hydrogen for light dependent reactions
