Photorespiration and Calvin Cycle Concepts

The video reviews the Calvin cycle, detailing its steps and highlighting inefficiencies in photosynthesis, particularly photorespiration. It explains how RuBisCo can react with both CO2 and O2, leading to less efficient sugar production. The video also introduces the concept of C3 photosynthesis and hints at alternative methods like C4 photosynthesis to overcome these inefficiencies.

What is the role of RuBisCo in the Calvin cycle?

• It generates ATP.

• It transports electrons.

• It fixes carbon dioxide into organic molecules.

• It splits water molecules.

Which molecule is initially formed in the Calvin cycle before converting to G3P?

• Glucose

• 3-phosphoglycerate

• Ribulose bisphosphate

• Oxygen

How many G3P molecules are used to regenerate ribulose bisphosphate in the Calvin cycle?

• Six

• One

• Two

• Five

What is the first stable product of carbon fixation in C3 photosynthesis?

• Oxygen

• Glucose

• 3-phosphoglycerate

• Ribulose bisphosphate

What happens during photorespiration?

• RuBisCo fixes carbon dioxide efficiently.

• RuBisCo reacts with oxygen, leading to less efficient sugar production.

• ATP is generated in large amounts.

• NADPH is converted to NADP+.

What is phosphoglycolate?

• A 2-carbon molecule

• A 3-carbon molecule

• A 6-carbon molecule

• A 5-carbon molecule

Why might photorespiration have been selected for in natural selection?

• It increases the efficiency of ATP production.

• It helps in reducing harmful oxygen levels in cells.

• It enhances glucose production.

• It prevents water loss.

What is one possible evolutionary reason for the existence of photorespiration?

• To manage excess oxygen in cells.

• To enhance the Calvin cycle efficiency.

• To provide an alternative pathway for glucose production.

• To increase oxygen levels in the atmosphere.

What is the main difference between C3 and C4 photosynthesis?

• C4 photosynthesis produces more oxygen.

• C3 photosynthesis occurs only in the dark.

• C4 photosynthesis involves an additional step to concentrate CO2.

• C3 uses RuBisCo, while C4 does not.

Which of the following is a waste product in photorespiration?

• ATP

• NADPH

• Phosphoglycolate

• Glucose