Photosynthesis and Carbon Fixation Quiz

What is the main purpose of the Calvin cycle in photosynthesis?

• To generate oxygen

• To convert light energy into chemical energy

• To reduce CO2 to sugar

• To produce ATP

Which enzyme catalyses the carbon fixation phase in the Calvin cycle?

• ATP synthase

• PEP carboxylase

• Rubisco

• NADP+ reductase

In C4 plants, where does the initial fixation of CO2 occur?

• Thylakoid membrane

• Bundle-sheath cells

• Mesophyll cells

• Stroma

What is the role of ATP synthase in the thylakoid membrane?

• To transport electrons

• To produce ATP from ADP and inorganic phosphate

• To fix carbon dioxide

• To split water molecules

Which of the following is a characteristic of CAM plants?

• They open their stomata during the day

• They fix carbon at night

• They use rubisco for initial CO2 fixation

• They are primarily found in cold climates

What is the main disadvantage of photorespiration in plants?

• It produces ATP

• It releases CO2 without producing sugar

• It increases water loss

• It enhances photosynthesis efficiency

Which molecule is regenerated at the end of the Calvin cycle?

• G3P

• RuBP

• NADPH

• ATP

What is the primary function of PEP carboxylase in C4 plants?

• To split water molecules

• To fix CO2 into four-carbon compounds

• To regenerate RuBP

• To produce NADPH

How do C4 plants minimise the cost of photorespiration?

• By using CAM pathway

• By closing stomata during the day

• By incorporating CO2 into four-carbon compounds

• By increasing oxygen concentration

What is the main product of the Calvin cycle that is used to form glucose and other organic compounds?

• ATP

• NADPH

• Glyceraldehyde 3-phosphate (G3P)

• Oxygen