Exam 3: 28 Photosynthesis II (1/3 complete)

Question 1

5. In higher plants, Rubisco is a protein complex comprising 16 subunits, 8 chloroplast genome-encoded large subunits and 8 nuclear genome-encoded small subunits. A carbamylation process is essentially required for activating the newly assembled Rubisco.

This type of modification takes place in which amino acid residue in the Rubisco active site?

A) Arg
B) Glu
C) Lys
D) Cys

Answer 1

C) Lys

Carbamylation of a lysine residue is essential for Rubisco activity.

This process is regulated by CO2, Mg2+, pH, and Rubisco activase, ensuring that Rubisco is active when conditions are favorable for photosynthesis.

Question 2

7. What type and number of cofactors are required to fix one CO2 molecule in the Calvin-Benson cycle?

A) 3 ATP + 3 NADPH
B) 2 ATP + 2 NADPH
C) 3 ATP + 2 NADPH
D) 2 ATP+ 3 NADPH

Answer 2

C) 3 ATP + 2 NADPH

To fix one CO2 molecule in the Calvin-Benson cycle, 3 ATP and 2 NADPH are required. These cofactors are products of the light-dependent reactions of photosynthesis.

Question 3

8. Which of the following is NOT a phase of the Calvin-Benson Cycle?

A) Carboxylation
B) Reduction
C) Regeneration
D) Photorespiration

Answer 3

D) Photorespiration

Question 4

Clicker:
Melvin Calvin and his colleagues noted that when 14CO2 was added to algal cells, a single compound was radiolabeled.

What is the compound?

A. A. Ribulose-5-phosphate
B. Glyceraldehyde-3-phosphate
C. Ribulose bisphosphate
D. 3-phosphoglycerate
E. 2-phosphoglycolate

Answer 4

D. 3-phosphoglycerate

Question 5

Clicker:
The major sugar transported to non photosynthesizing cells in plants is:

A. sucrose.
B. fructose.
C. glucose.
D. ribose.
E. None of the above

Answer 5

A. sucrose.