The following diagram shows the ${\mathrm{C}}_4$ photosynthetic carbon cycle. A and B can respectively be:
   
1. Pyruvate; malate or aspartate
2. Phoshoglycerate; fumarate or aspartate
3. Phosphoenol pyruvate; malate or aspartate
4. Phosphoenol pyruvate; fumarate or aspartate

The relationship between photosynthesis and respiration can be best described as:

Identify the incorrect statement regarding the enzyme PEP carboxylase:
1. PEP carboxylase has a lower Km for bicarbonate ions, hence, higher affinity — than RuBisCO.
2. ${\mathrm{O}}_2$ is a very poor substrate for this enzyme.
3. It plays an important role in ${\mathrm{C}}_4$ cycle but not in CAM plants.
4. PEP carboxylase is also significant in non-photosynthetic metabolic pathways.

What can occur during both photosynthesis and respiration?
I: The reduction of oxygen that forms water.
II: Formation of ATP by chemiosmosis

Carbon dioxide splits to form oxygen during:
1. photosynthesis.
2. respiration.
3. photorespiration.
4.None.

Identify the correct statements regarding factors affecting photosynthesis:
I. At very high light intensities chlorophyll damage can occur due to photo-oxidation.
II. Affinity for carbon dioxide of the enzyme RuBisCO is reduced at higher temperatures.
III. The current availability of carbon dioxide may be a limiting factor for C₃ plants.
IV. If leaf undergoes senescence, loss of chlorophyll occurs.

Probably the strongest biological oxidizing agent is P680+ because:

What conclusion can be drawn from the finding that while some bacteria have only photosystem I, cyanobacteria have both?
1. Photosystem II was lost in some species as it was selected against by the nature.
2. Photosystem I must be more ancestral.
3. Photosystem II may have evolved to be more photoprotective.
4. Cyclic photphosprolylation is more important than non cyclic photophosphorylation.

The functions of carotenoids similar to their function in humans would be:
1. Accessory pigments to harvest light energy.
2. Dissipation of excessive light energy.
3. Antibacterial in nature.
4. Removal of toxins from water.

In chloroplasts the ${\mathrm{CF}}_1$ part of the ATP synthase is located:
1. on the side facing the thylakoid space.
2. on the ATP molecules themselves.
3. on the pigment molecules of PS I and PS II.
4. on the stroma side of the membrane.