Photosynthesis Basic Concepts 3

Question 1

What is the approximate ATP yield from one full turn of the Calvin cycle per CO₂ fixed?

Accepted Answer

3 ATP

Answer

Three ATP molecules are consumed per CO₂ fixed during one turn of the Calvin cycle.

Question 2

Which enzyme catalyzes carbon fixation in the Calvin cycle?

Accepted Answer

RuBisCO

Answer

RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) is the enzyme that combines CO₂ with RuBP.

Question 3

In which direction do electrons flow in the photosynthetic electron transport chain?

Accepted Answer

From water to NADP+

Answer

Electrons flow from water (via splitting) through the electron transport chain to ultimately reduce NADP+ to NADPH.

Question 4

How many molecules of CO₂ must be fixed to produce one molecule of glucose?

Accepted Answer

6

Answer

Six CO₂ molecules are required because glucose (C₆H₁₂O₆) contains six carbon atoms.

Question 5

What is the function of the antenna complex in a photosystem?

Accepted Answer

Absorb and transfer light energy to the reaction center

Answer

Antenna pigments harvest light energy and funnel it to the reaction center chlorophyll for photochemistry.

Photosynthesis Practice Test