Lecture 16

Question 1

What are the three phases of the Calvin cycle?

Answer 1

-carbon fixation
-reduction
-regeneration
^ in that order

Question 2

Describe carbon fixation?

Answer 2

• each CO2 attached to ribulose bisphosphate (RuBP) by the enzyme RUBISCO
• product unstable
• splits into 3 carbon sugars

Question 3

Describe reduction

Answer 3

• 3 carbon sugars are phosphorylated by ATP
• reduced by NADPH
• lose phosphate group
• G3P molecule produced and leaves

Question 4

Describe regeneration of RuBP

Answer 4

Carbon skeletons of G3P rearranged to form RUBP, uses 3 ATP

Question 5

What is the cyclical electron flow?

Answer 5

Alternate mode of photosynthesis that only involves first electron chain carriers and psi

Question 6

What is a stroma?

Answer 6

Pores in plants to bring in CO2 and release water

Question 7

What are bundle sheath cells?

Answer 7

Layer of cells between vascular tissue and stroma

Question 8

Describe the daily acid cycle in CAM plants

Answer 8

• Decrease in PH over night- increase in crassulacean acid production
• build up of starch I.e Calvin cycle through the day

Question 9

Why does rubisco bind with O 2 as well as CO2?

Answer 9

Rubisco first involved at a time when the atmosphere had far less O2 and more CO2