In cyclic photophosphorylation, the primary electron acceptor is:
1. An iron-sulfur protein
2. Plastocyanin
3. Plastoquinone
4. Water

If chloroplasts are illuminated with sunlight, the lowest pH would be observed in:

To establish a proton gradient across the thylakoid membrane, the protons are provided by:

Heme and iron-sulfur complexes in photosynthesis:
1. act as reducing agents
2. act as oxidizing agents
3. both oxidize and reduce during electron transport
4. are needed only in respiration but not in photosynthesis

Identify the correct statement:

The pathway shown in the figure will be seen in:

1. ${\mathrm{C}}_4$ plants
2. CAM plants
3. ${\mathrm{C}}_3$ plants
4. All photosynthetic plants

Carbon dioxide fixation will be inhibited by oxygen in:

1. cell I only.
2. cell II only.
3. neither cell I nor cell II.
4. both cell I and cell II.

Radioactive carbon [${}^{14}\mathrm{C}$] was fed to a plant during the day and after a short time was traced to oxaloacetate. The plant used in the experiment will be:

${\mathrm{C}}_4$ plants are able to photosynthesize with no apparent photorespiration because of:
1. absence of Calvin cycle.
2. use of PEP carboxylase for primary carbon dioxide fixation.
3. absence of RuBisCO.
4. presence of tissues that do not require oxygen.

CAM plants:
1. fix carbon dioxide during the night into organic acids.
2. fix carbon dioxide into organic acids in the bundle-sheath cells during the day.
3. fix carbon dioxide into pyruvate in the mesophyll cells during the night.
4. use both photosystems I and II at night.