In cyclic electron flow:
1. the electron begins in a pigment complex called photosystem I, passes from the primary acceptor to ferredoxin and then to plastoquinone, then to cytochrome b6f, and then to plastocyanin before returning to chlorophyll.
2. the electron begins in a pigment complex called photosystem II, passes from the primary acceptor to ferredoxin and then to plastoquinone, then to cytochrome b6f, and then to plastocyanin before returning to chlorophyll.
3. the electron begins in a pigment complex called photosystem I, passes from the primary acceptor to ferredoxin and then to plastocyanin, then to cytochrome b6f, and then to plastoquinone before returning to chlorophyll.
4. the electron begins in a pigment complex called photosystem II, passes from the primary acceptor to ferredoxin and then to plastocyanin, then to cytochrome b6f, and then to plastoquinone before returning to chlorophyll.

Identify the incorrect statement regarding non-cyclic photophosphorylation:
1. Being a light reaction, non-cyclic photophosphorylation occurs in the thylakoid membrane.
2. The photosystem II complex replaces its lost electrons from an external source.
3. It generates both ATP and NADPH
4. When the chloroplast runs low on ATP for the Calvin cycle, the plant may shift from cyclic to non-cyclic electron flow.

The light independent reactions are seen in:
I. ${\mathrm{C}}_3$ carbon fixation
II. ${\mathrm{C}}_4$ carbon fixation
III. Crassulacean acid metabolism

In the light dependent reactions of photosynthesis:
1. NADPH is reduced to ${\mathrm{NADP}}^{+}$ by the enzyme NADP reductase.
2. initial carbon fixation takes place forming a 3 carbon compound.
3. ATP is not produced.
4. light is absorbed and energy is transported to reaction-center chlorophyll a

Photosystem I is directly associated with:
1. passing electrons to plastoquinone
2. receiving electrons from plastocyanin
3. P680 as the chlorophyll a reaction-center
4. removal of electrons and protons from water

Light dependent reactions are so called because they require light:

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?

Identify the correct statement:
1. The light reactions provide ATP and NADPH to the Calvin cycle.
2. The light reactions provide ${\mathrm{CO}}_2$ to the Calvin cycle.
3. The light reactions supply oxygen to the Calvin cycle.
4. Calvin cycle is in no way dependent on the light reactions.

What is true for both light reactions and the Calvin cycle of photosynthesis in plants?
1. Production of molecular oxygen
2. Depend directly or indirectly on light
3. Requirement of ATP
4. Production of NADPH