Assertion A: Photorespiration is a wasteful process in C3 plants. Reason R: In photorespiration, RuBisCO binds O₂, no sugar, ATP or NADPH is formed, and CO₂ is released with the use of ATP. Choose the correct answer.

Both A and R are correct and R is the correct explanation of A

A is correct but R is not correct

A is not correct but R is correct

Both A and R are correct but R is not the correct explanation of A

Priestley kept a mint plant in a closed bell jar with a burning candle, and with a mouse in another trial. Which conclusion did he draw?

Plants restore what candles and breathing animals remove from air

Plants release the CO₂ that a candle needs to keep burning

Plants purify the air only when they are placed in sunlight

Green plant parts store the glucose they make as starch

Photosynthesis in Higher Plants

15 NEET-UG practice questions on Photosynthesis in Higher Plants, part of Botany. The first 15 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Medium
A leaf makes three molecules of glucose through the Calvin cycle. How much ATP and NADPH does this require in all?
1. A18 ATP and 12 NADPH
2. B54 ATP and 18 NADPH
3. C54 ATP and 36 NADPH
4. D36 ATP and 54 NADPH
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Answer: C · 54 ATP and 36 NADPH
Fixing one CO₂ needs 3 ATP and 2 NADPH, and one glucose needs six turns, so one glucose uses 18 ATP and 12 NADPH. Three glucose molecules need 3 × 18 = 54 ATP and 3 × 12 = 36 NADPH. Check: 18 CO₂ × 3 = 54 and 18 CO₂ × 2 = 36.
- A: This is the need for only one glucose.
- B: The ATP is right, but NADPH was counted as one per CO₂.
- D: This swaps the ATP and NADPH figures.
Remember this
Per CO₂ fixed, 3 ATP and 2 NADPH; per glucose, 6 turns, 18 ATP and 12 NADPH.
Question 2 · Medium
Assertion A: Photorespiration is a wasteful process in C3 plants. Reason R: In photorespiration, RuBisCO binds O₂, no sugar, ATP or NADPH is formed, and CO₂ is released with the use of ATP. Choose the correct answer.
1. AA is correct but R is not correct
2. BBoth A and R are correct and R is the correct explanation of A
3. CA is not correct but R is correct
4. DBoth A and R are correct but R is not the correct explanation of A
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Answer: B · Both A and R are correct and R is the correct explanation of A
When RuBisCO binds O₂, RuBP forms one 3-phosphoglyceric acid and one phosphoglycolate. The pathway makes no sugar, ATP or NADPH and even spends ATP while releasing CO₂. That is exactly why it is wasteful.
- A: R is a correct account of photorespiration.
- C: A is correct, as NCERT calls the pathway wasteful.
- D: R directly states why the process is wasteful.
Remember this
Photorespiration occurs in C3 plants, needs O₂ at RuBisCO, makes nothing useful, and is absent in C4 plants.
Question 3 · Easy
Priestley kept a mint plant in a closed bell jar with a burning candle, and with a mouse in another trial. Which conclusion did he draw?
1. APlants release the CO₂ that a candle needs to keep burning
2. BPlants purify the air only when they are placed in sunlight
3. CPlants restore what candles and breathing animals remove from air
4. DGreen plant parts store the glucose they make as starch
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Answer: C · Plants restore what candles and breathing animals remove from air
The candle went out and the mouse died in a closed jar without a plant, but both continued when a mint plant was present. Priestley inferred that plants restore something to the air that burning and breathing use up.
- A: Candles need oxygen, not CO₂, so this reverses the gas involved.
- B: The need for sunlight was shown later by Ingenhousz.
- D: This was the finding of Julius von Sachs.
Remember this
Priestley showed plants restore air; Ingenhousz added the need for sunlight; Sachs showed glucose and starch formation.
Question 4 · Easy
Within the mesophyll cells of maize, which molecule is the primary acceptor of CO₂?
1. APhosphoenol pyruvate
2. BRibulose bisphosphate
3. C3-phosphoglyceric acid
4. DOxaloacetic acid
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Answer: A · Phosphoenol pyruvate
Maize is a C4 plant. Its mesophyll cells fix CO₂ onto the 3-carbon molecule phosphoenol pyruvate using PEP carboxylase, which forms the 4-carbon oxaloacetic acid.
- B: RuBP accepts CO₂ in the Calvin cycle, which runs in the bundle sheath of maize.
- C: 3-phosphoglyceric acid is the first product of the C3 pathway.
- D: Oxaloacetic acid is the product of this fixation, not the acceptor.
Remember this
In C4 plants PEP (3C) accepts CO₂ in mesophyll, OAA (4C) is the first product, and RuBP works later in bundle sheath.
Question 5 · Hard
Read these statements on the Z-scheme. A. The electron lost by P680 is replaced by electrons from the splitting of water. B. Electrons passing from PS II to PS I move uphill on the redox scale. C. Light must be absorbed by both PS II and PS I for NADPH to form. D. Non-cyclic flow forms NADPH but no ATP. Which of these are correct?
1. AB and D only
2. BA, C and D only
3. CA and C only
4. DA, B and C only
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Answer: C · A and C only
Water splitting fills the hole left in P680, and both photosystems must be excited for electrons to reach NADP⁺. Travel from PS II to PS I is downhill on the redox scale, so B fails. Non-cyclic flow forms both ATP and NADPH, so D fails.
- A: A and C are true, and neither B nor D is correct.
- B: D is false, because non-cyclic flow also makes ATP.
- D: B is false, because the chain between the photosystems runs downhill.
Remember this
Excitation lifts electrons uphill; the chain between PS II and PS I runs downhill and supports ATP synthesis.
Question 6 · Medium
Given below are two statements: Statement I: Cyclic photophosphorylation forms both ATP and NADPH + H⁺. Statement II: The stroma lamellae lack PS II and NADP reductase. Choose the correct answer.
1. AStatement I is incorrect but Statement II is correct
2. BStatement I is correct but Statement II is incorrect
3. CBoth Statement I and Statement II are correct
4. DBoth Statement I and Statement II are incorrect
Answer and explanation in LearnFree account
Question 7 · Easy
What does cyclic photophosphorylation produce?
1. AATP only
2. BATP and NADPH + H⁺
3. CNADPH + H⁺ only
4. DATP, NADPH + H⁺ and O₂
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Question 8 · Medium
Match List-I with List-II. List-I (scientist) A. Julius von Sachs B. Jan Ingenhousz C. Cornelius van Niel D. Joseph Priestley List-II (contribution) I. Hydrogen from an oxidisable compound reduces CO₂, inferred from sulphur bacteria II. Glucose is made in green parts and is usually stored as starch III. Plants restore air spoiled by a candle or a mouse IV. Sunlight is needed, shown by bubbles on green parts of an aquatic plant
1. AA-II, B-III, C-IV, D-I
2. BA-I, B-IV, C-II, D-III
3. CA-IV, B-II, C-I, D-III
4. DA-II, B-IV, C-I, D-III
Answer and explanation in LearnFree account
Question 9 · Hard
A well-watered C3 leaf at its optimum temperature receives 40% of full sunlight in air containing about 0.03% CO₂. Going by Blackman's law of limiting factors, which change will raise its photosynthesis most?
1. ARaising the temperature well above the optimum
2. BGiving the plant more water
3. CRaising CO₂ to 0.05%
4. DDoubling the light to 80% of full sunlight
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Question 10 · Hard
Given below are two statements: Statement I: C4 plants show no photorespiration because the breakdown of a C4 acid raises the CO₂ level around RuBisCO in the bundle sheath. Statement II: In C4 plants, the Calvin cycle runs in the mesophyll cells. Choose the correct answer.
1. AStatement I is incorrect but Statement II is correct
2. BStatement I is correct but Statement II is incorrect
3. CBoth Statement I and Statement II are incorrect
4. DBoth Statement I and Statement II are correct
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Question 11 · Medium
Tomato and bell pepper give higher yields in greenhouses enriched with CO₂. Which fact explains this?
1. AThese C4 crops saturate at about 360 μL L⁻¹ of CO₂
2. BExtra CO₂ makes these crops need more light than full sunlight
3. CExtra CO₂ stops the closing of their stomata
4. DThese C3 crops keep raising their photosynthesis at CO₂ levels above the atmospheric level
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Question 12 · Medium
Which of the following does NOT help to build the proton gradient across the thylakoid membrane?
1. AMovement of protons through CF₀ into the stroma
2. BTransfer of protons from stroma to lumen during electron transport
3. CSplitting of water on the lumen side of the membrane
4. DRemoval of stromal protons when NADP reductase reduces NADP⁺
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Question 13 · Medium
Consider these statements on the C4 pathway. A. Bundle sheath cells have thick walls and no intercellular spaces. B. RuBisCO is abundant in the mesophyll cells. C. PEP carboxylase is present in the mesophyll cells. D. A C4 acid releases CO₂ in the bundle sheath cells. Which of these are correct?
1. AB and C only
2. BA and B only
3. CA, B and D only
4. DA, C and D only
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Question 14 · Medium
Arrange the following in the order an electron meets them during non-cyclic flow, starting from its source. A. Reaction centre P700 B. Water C. Cytochromes of the electron transport chain D. Reaction centre P680
1. AB, A, C, D
2. BD, C, B, A
3. CB, D, C, A
4. DD, B, C, A
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Question 15 · Easy
In Engelmann's experiment, a prism split the light falling on the alga Cladophora kept in a suspension of aerobic bacteria. In which regions of the spectrum did the bacteria collect most?
1. AYellow and orange
2. BGreen and yellow
3. CGreen and red
4. DBlue and red
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Photosynthesis in Higher Plants

A leaf makes three molecules of glucose through the Calvin cycle. How much ATP and NADPH does this require in all?

Assertion A: Photorespiration is a wasteful process in C3 plants. Reason R: In photorespiration, RuBisCO binds O₂, no sugar, ATP or NADPH is formed, and CO₂ is released with the use of ATP. Choose the correct answer.

Priestley kept a mint plant in a closed bell jar with a burning candle, and with a mouse in another trial. Which conclusion did he draw?

Within the mesophyll cells of maize, which molecule is the primary acceptor of CO₂?

Given below are two statements: Statement I: Cyclic photophosphorylation forms both ATP and NADPH + H⁺. Statement II: The stroma lamellae lack PS II and NADP reductase. Choose the correct answer.

What does cyclic photophosphorylation produce?

A well-watered C3 leaf at its optimum temperature receives 40% of full sunlight in air containing about 0.03% CO₂. Going by Blackman's law of limiting factors, which change will raise its photosynthesis most?

Given below are two statements: Statement I: C4 plants show no photorespiration because the breakdown of a C4 acid raises the CO₂ level around RuBisCO in the bundle sheath. Statement II: In C4 plants, the Calvin cycle runs in the mesophyll cells. Choose the correct answer.

Tomato and bell pepper give higher yields in greenhouses enriched with CO₂. Which fact explains this?

Which of the following does NOT help to build the proton gradient across the thylakoid membrane?

Consider these statements on the C4 pathway. A. Bundle sheath cells have thick walls and no intercellular spaces. B. RuBisCO is abundant in the mesophyll cells. C. PEP carboxylase is present in the mesophyll cells. D. A C4 acid releases CO₂ in the bundle sheath cells. Which of these are correct?

Arrange the following in the order an electron meets them during non-cyclic flow, starting from its source. A. Reaction centre P700 B. Water C. Cytochromes of the electron transport chain D. Reaction centre P680

In Engelmann's experiment, a prism split the light falling on the alga Cladophora kept in a suspension of aerobic bacteria. In which regions of the spectrum did the bacteria collect most?