1Where specifically does the light-dependent stage occur?
Thylakoid membranes (grana).
2What is the role of accessory pigments?
To absorb light of different wavelengths and pass the energy to the reaction centre.
3Define an action spectrum.
A graph showing the rate of photosynthesis at different wavelengths of light.
4What is the reaction centre pigment?
Chlorophyll a.
5What are the products of the light-dependent stage?
ATP, reduced NADP, and oxygen.
6Define photolysis.
The splitting of water using light energy: H₂O → 2H⁺ + 2e⁻ + ½O₂.
7What is the role of Rubisco?
To catalyse the carboxylation of RuBP (ribulose bisphosphate).
8Where does the light-independent stage occur?
The stroma of the chloroplast.
9What is the first 3C compound in the Calvin cycle?
Glycerate-3-phosphate (GP).
10How is GP converted to Triose Phosphate (TP)?
Using ATP and reduced NADP from the light-dependent stage.
11What happens to most of the Triose Phosphate?
It is used to regenerate RuBP (requires ATP).
12Name three limiting factors of photosynthesis.
Light intensity, CO₂ concentration, and temperature.
13What is the compensation point?
The light intensity at which the rate of photosynthesis exactly matches the rate of respiration.
14Why is magnesium essential for photosynthesis?
It is the central ion in the chlorophyll molecule.
15What are the signs of nitrogen deficiency in plants?
Stunted growth and chlorosis (yellowing) of older leaves.
16What is cyclic photophosphorylation?
Electrons from PSI return to PSI via the ETC to produce ATP only.
17What is the wavelength of light absorbed by PSII?
680 nm (P680).
18How does high light intensity affect chloroplast arrangement?
They move to the side of the cell (perpendicular) to avoid damage.
19What is the role of the antenna complex?
To harvest light energy and funnel it to the reaction centre.
20From which molecule is glucose produced in the Calvin cycle?
Triose phosphate (TP).
21Why does the Calvin cycle stop in the dark?
ATP and reduced NADP are no longer produced by the light-dependent stage.
22How can GP be used by the plant?
To synthesise amino acids (with nitrates) and fatty acids.
23What is the Z-scheme?
A flow chart representing non-cyclic photophosphorylation.
24What is the function of NADP?
It is a coenzyme that acts as a final electron and hydrogen acceptor.
25Why is CO₂ concentration usually the most common limiting factor?
Atmospheric CO₂ is low (approximately 0.04%).
26What happens to Rubisco at very high temperatures?
It denatures, stopping the Calvin cycle.
27Where are the photosynthetic pigments located?
In the thylakoid membranes.
28Name an accessory pigment.
Chlorophyll b, carotene, or xanthophyll.
29What is the source of electrons for PSII?
The photolysis of water.
30What is the destination of the oxygen produced in photosynthesis?
It is used in respiration or diffuses out through the stomata.