Q. No.Energy is transferred from the light reaction step to the dark reaction step by
1. chlorophyll
2. ADP
3. ATP
4. RuBP
Subtopic: Introduction | Historical View: Experiments | Chloroplast Structure | Photosynthetic Pigments | Redtrop Experiment | Emerson's Enhancement Experiment | Photosystems | Light Reaction: Electron Transport | Light Reaction: Photophosphorylation | Dark Reaction: Biosynthetic Phase |
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The process which makes major difference between C3 and C4 plants is:
| 1. | glycolysis | 2. | Calvin cycle |
| 3. | photorespiration | 4. | respiration |
Subtopic: C4 Cycle (Hatch & Slack Pathway) | Photorespiration |
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Photorespiration is avoided by C4 plants primarily because:
| 1. | They do not participate in the Calvin cycle. |
| 2. | They use PEP carboxylase to initially fix CO2. |
| 3. | They conserve water more efficiently. |
| 4. | They are adapted to cold, wet climates. |
Subtopic: C4 Cycle (Hatch & Slack Pathway) | Photorespiration |
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Photorespiration in plants:
| 1. | increases the efficiency of photosynthesis by capturing more CO₂. |
| 2. | leads to the production of glucose and oxygen. |
| 3. | results in a significant release of CO₂ and consumption of ATP without the production of ATP or NADPH. |
| 4. | It enhances the plant's ability to fix nitrogen. |
Subtopic: Photorespiration |
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A process that makes an important difference between C3 and C4 plants is:
1. Transpiration
2. Glycolysis
3. Photosynthesis
4. Photorespiration
Subtopic: Photorespiration |
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AIPMT - 2012
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In C₄ plants, the enzyme PEP carboxylase catalyzes the initial fixation of CO₂ in mesophyll cells. Why does the subsequent release of CO₂ in bundle sheath cells favor efficient photosynthesis?
| 1. | It prevents excess ATP consumption in the mesophyll cells, improving energy efficiency. |
| 2. | It maintains a high CO₂ concentration around Rubisco, reducing oxygenase activity and photorespiration. |
| 3. | It allows direct participation of PEP carboxylase in the Calvin cycle, increasing sugar synthesis. |
| 4. | It eliminates the need for light-dependent reactions, making photosynthesis independent of light intensity. |
Subtopic: Photorespiration |
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What determines whether RuBisCO binds to CO2 or O2?
| 1. | The concentration of RuBP in the chloroplast |
| 2. | The availability of ATP and NADPH |
| 3. | The temperature of the environment |
| 4. | The relative concentrations of CO2 and O2 |
Subtopic: Photorespiration |
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Photorespiration would affect __________ the most.
1. C4 plants
2. heterotrophs
3. C3 plants
4. CAM plants
Subtopic: Photorespiration |
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What would be the immediate consequence if the enzyme RuBisCO’s oxygenation activity increased significantly in C3 plants due to elevated oxygen concentrations?
| 1. | Increased ATP and NADPH production |
| 2. | Increased glucose synthesis |
| 3. | Decreased net carbon fixation due to enhanced photorespiration |
| 4. | No effect on the rate of photosynthesis |
Subtopic: Photorespiration | Summary |
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Given below are two statements:
| Assertion (A): | CO2 fixation is decreased in C3 plants. |
| Reason (R): | In C3 plants, some O2 bind to RuBisCo |
| 1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
| 3. | (A) is true but (R) is false. |
| 4. | Both (A) and (R) are false. |
Subtopic: Photorespiration |
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