17 Questions
Which phase of the Calvin cycle involves the formation of two molecules of 3-phosphoglycerate?
Carboxylation
What is the main purpose of the dark reactions in photosynthesis?
Reduce CO2 to carbohydrate
Which enzyme catalyzes the carboxylation of ribulose-1,5-bisphosphate in the Calvin cycle?
Rubisco
What is the primary factor that directly regulates the stroma reactions in photosynthesis?
Light
How many stages are involved in the Calvin cycle?
Three stages
What proportion of triose phosphate is typically used for sucrose or starch production in the Calvin cycle?
One-sixth
What is the main reason why the forward reaction of the carboxylation of ribulose-1,5-bisphosphate is strongly favored?
Low concentration of CO2 in photosynthetic cells
What enzyme represents up to 40% of the total soluble protein in most leaves?
Rubisco
What regulates the Calvin cycle through light-dependent enzyme activation?
Ribulose-5-phosphate kinase
What factor determines the balance between the Calvin cycle and the C2 oxidative photosynthetic carbon cycle?
The concentrations of the substrates CO2 and O2
What is calculated to be about 4 mM within the chloroplast stroma?
Concentration of rubisco active sites
What happens to the concentration of CO2 in a solution in equilibrium with air as the temperature increases?
Decreases more than O2
How does the concentration ratio of CO2 to O2 change as the temperature rises?
Decreases
What effect does increasing temperatures have on photorespiration and photosynthesis?
Increases relative to photosynthesis
What is the impact of rubisco's kinetic properties at higher temperatures?
Enhances relative increase in oxygenation
Why is it difficult to measure the rate of photorespiration in intact cells?
Because it is concurrent with photosynthesis
How much carbon entering the C2 oxidative photosynthetic carbon cycle is theoretically released as CO2?
One-fourth
This quiz covers the process of carbon reactions in the Calvin Cycle of photosynthesis, including the reduction of CO2 to carbohydrate in the stroma of chloroplasts. It also explores how these reactions are coupled with the generation of ATP and NADPH in the thylakoid membrane.
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