Chapter 21 Self-test questions

. Which of the following statements about photosynthesis is correct?

Carbohydrates are the source of electrons in photosynthesis.

CO₂ is the source of electrons in photosynthesis.

Water is the source of electrons in photosynthesis.

NADH is the source of electrons in photosynthesis.

. Which of the following statements about thylakoids is not correct?

The thylakoid membranes contain chlorophyll pigments.

The thylakoid membranes contain the photosystems.

The thylakoid membranes contain the Calvin cycle enzymes.

The thylakoid membranes contain the electron transport machinery.

. Which of the following statements about the mechanism of the light-dependent reactions of photosynthesis is correct?

Electrons from photosystem I reduce NADPH.

Electrons from photosystem I reduce pheophytin.

Electrons from NADPH revert photosystem II back to the ground state.

Ferredoxin-NADP reductase reduces NADP⁺ to NADPH.

. Which of the following statements about cyclic photophosphorylation is correct?

Cyclic photophosphorylation utilizes excess ATP.

Cyclic photophosphorylation reduces NADP⁺ to NADPH.

Cyclic photophosphorylation occurs in the cytochrome bf complex and utilizes electrons from photosystem I.

Cyclic photophosphorylation utilizes electrons from photosystem II.

. Which of the following statements about the mechanism of the Calvin cycle is correct?

The Calvin cycle is a metabolic pathway by which plants convert CO₂ into pentose sugars as the main product.

The Calvin cycle enzymes are more reactive if there is a decrease in light intensity.

In the Calvin cycle rubisco adds CO₂to 3-phosphoglycerate

The Calvin cycle is a metabolic pathway by which plants convert CO₂ and water into carbohydrates.

. Which reaction in photosynthesis is carried out by 'Rubisco' or ribulose 1-,5 bisphosphate carboxylase?

Conversion of 3 phosphoglycerate into glyceraldehyde 3 phosphate.

Utilisation of CO₂ to produce 3 phosphoglycerate.

Conversion of glyceraldehyde 3 phosphate into ribulose 5 phosphate.

Carboxylation of phosphoenol pyruvate to oxaloacetate.

. Which of the following statements about chlorophyll is correct?

Chlorophyll molecules make up the electron transport chains in photosynthesis.

Chlorophyll molecules are found in the chloroplast stroma.

Chlorophyll molecules appear green because they reflect light in the red and blue ranges.

Chlorophyll molecules are the photosynthetic pigments in the thylakoid membrane.

. Which of the following statements about photosystem I in chloroplasts are correct? Please select all that apply.

Photosystem I is activated by light independently from Photosystem II.

Plastocyanin reduces photooxidised P700 in PSI.

Plastocyanin reduces photooxidised P680 in PSI.

Electrons ejected from P700 in photosystem I are replaced with electrons from water.

The Calvin Cycle occurs only in light.

. Which of the following statements about C₄ plants are correct? Please select all that apply.

C₄ plants minimize the oxygenase activity of Rubisco by fixing CO₂into PEP (phosphoenolpyruvate).

C₄ plants minimize the oxygenase activity of Rubisco by fixing CO₂into oxaloacetate.

C₃ plants are more efficient in photosynthesis than are C₄ plants.

C₄ plants are more efficient in photosynthesis than are C₃ plants.

C₄ plants mainly occur in areas of high temperature and light intensity.

. What are the products of the light reactions of photosynthesis?

Oxygen, carbon dioxide, and ATP.

Oxygen, NADPH, and ATP.

Oxygen, NADH, and ATP.

Oxygen and carbohydrate.

. Which are the possible fates of carbohydrate produced in photosynthesis in green plants?

It can be stored as starch.

It can be converted into fats and stored.

It can be converted into ribose sugars.

It is used to convert ADP to ATP.

. Why are some types of plants referred to as C4 plants?

They produce oxaloacetate using CO_2.

They produce ribulose phosphate from CO_2.

They fix carbon dioxide directly to glucose.

They fix carbon dioxide to pyruvate.

Chapter 21 Self-test questions

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