Chapter 20, Problem 1P

Interpretation Introduction

Interpretation:

The statement not true about Calvin cycle.

Concept introduction:

The Calvin cycle is the set of reactions in the photosynthesis which uses the products of light-dependent reactions and produces glucose. The reactions of Calvin cycle doesn’t need light directly (but uses the products of light reaction) and can takes place in the absence of light also.

Answer to Problem 1P

The correct answer is option (d) is dependent on the light reactions.

Explanation of Solution

Reason for correct option:

Option (d) It is dependent on the light reactions: The Calvin cycle is light-independentas it could occur in the absence of sunlight, after the energy has been captured by the light reactions to produce NADPH and ATP. The products of the light reaction are used in the Calvin cycle. Each step consists of its own specific enzyme.

So, the correct answer is option (d).

Conclusion

Reasons for incorrect options:

Option(a) Cannot occur in the light:

The Calvin cycle refers to the light-independent reactions of photosynthesis. The Calvin Cycledoes not depend directly on light, it indirectly depends on lightasthe required energy carriers ATP and NADPH are products of light-dependent reactions.So, it does not require light, but the reactions are feasible in the presence of light also. Thus, this is an incorrect option.

Option (b) Is independent of the light reactions:

The energy from the sun is converted and packaged into ATP and NADPH. These light reaction products are used by the Calvin cycle. So, this is an incorrect option.

Option (c) Is a requirement for photosynthetic plantsbut has no effect on the rest of the biosphere:

Calvin cycle completes the route that carbon travels through a plant during photosynthesis. This is the metabolic pathway by which carbon dioxide (CO₂) is incorporated into carbohydrate. Thisaffects the biosphere.So, this is an incorrect option.