Quiz on Photorespiration

What is photorespiration?

• The process of producing oxygen.

• Consumption of oxygen and release of carbon dioxide during photosynthesis.

• Fixation of carbon dioxide in plants.

• Conversion of glucose to starch.

Why does photorespiration occur more on hot, dry days?

• Stomata remain open, allowing oxygen in.

• Stomata close to prevent water loss, reducing CO₂ levels in leaves.

• Plants produce more water.

• Rubisco becomes inactive.

Which enzyme is responsible for photorespiration?

• PEP carboxylase

• Rubisco

• ATP synthase

• NADP reductase

What is the substrate of Rubisco during photorespiration?

• Carbon dioxide

• Oxygen

• Glucose

• Water

What compound is initially formed when Rubisco acts as an oxygenase?

• Malate

• Glycolate

• Pyruvate

• Oxaloacetate

What is a consequence of photorespiration?

• ATP is produced.

• Carbon dioxide is fixed.

• Photosynthetic output decreases.

• NADPH is synthesized.

Which type of plants have evolved mechanisms to reduce photorespiration?

• C3 plants

• C4 plants

• Shade plants

• CAM plants

What is the role of PEP carboxylase in C4 plants?

• Fixing oxygen.

• Fixing carbon dioxide to a 3C compound.

• Producing glycolate.

• Synthesizing glucose.

What is the advantage of PEP carboxylase over Rubisco?

• Higher efficiency in fixing oxygen.

• No oxygenase activity and effective CO₂ fixation.

• It requires less energy.

• It is found in all plant cells.

What is the initial product of CO₂ fixation by PEP carboxylase in C4 plants?

• Glycolate

• Oxaloacetate

• G3P

• Pyruvate