Photosynthesis in Higher Plants: the chapter NEET asks most

Free questions

30 solved MCQs, answer marked and reasoning written out

Every question below is free to read — no sign-up, no email. 3 of them are real questions from past NEET papers. The other 264 questions in this chapter are in the book and in practice access.

1. Q1 Multi-statement analysis

   The light harvesting complexes (LHC): (i) are made up of hundreds of pigment molecules bound to proteins (ii) each photosystem has all the pigments except one molecule of chlorophyll a forming the antennae (iii) the single chlorophyll a molecule forms the reaction centre (iv) PS I and PS II are named in the sequence in which they function. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; the photosystems are named in the sequence of their DISCOVERY, not function, so (iv) is wrong.

   What this is testing: what a light harvesting complex is, and why the photosystems carry their numbers.

   (i) is correct. An LHC is made of hundreds of pigment molecules held on proteins.
   (ii) is correct. All those pigments except one chlorophyll a molecule form the antennae.
   (iii) is correct. That single chlorophyll a molecule is the reaction centre.
   (iv) is the trap. PS I and PS II are named in the order in which they were DISCOVERED, not the order in which they work. In the light reaction PS II actually acts first and PS I second.

   So three are correct.

   Hundreds of pigments gather the light; one chlorophyll a molecule does the chemistry. The antenna collects, the reaction centre acts.

   NCERT Class 11 Biology, page 138

2. Q2 Multi-statement analysis

   Regarding the terms light and dark reaction: (i) light reactions are directly light driven (ii) dark reactions are not directly light driven (iii) dark reactions depend on the products of light reactions, ATP and NADPH (iv) dark reactions occur only in darkness. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; dark reactions do NOT require darkness, so (iv) is wrong.

   What this is testing: whether the word 'dark' in dark reaction means darkness.

   (i) is correct. Light reactions are driven directly by light.
   (ii) is correct. Dark reactions are not driven directly by light.
   (iii) is correct. They run on the ATP and NADPH made in the light reaction.
   (iv) is the trap. Dark reactions do NOT need darkness. They are called dark only because light is not needed for the steps themselves; in a living leaf they run in daylight, using the products just made next door.

   So three are correct. The name describes what is not required, not when it happens.

   Dark reactions do not need darkness, only the products of light. The name is a historical accident and the question exploits it.

   NCERT Class 11 Biology, page 136

3. Q3 Multi-statement analysis

   The biosynthetic phase: (i) does not directly depend on the presence of light (ii) depends on the products of the light reaction, ATP and NADPH (iii) also needs CO2 and H2O (iv) stops immediately the moment light becomes unavailable. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; it continues for some time after light is withdrawn, so (iv) is wrong.

   What this is testing: what the biosynthetic phase depends on.

   (i) is correct. It does not need light directly.
   (ii) is correct. It runs on ATP and NADPH from the light reaction.
   (iii) is correct. CO2 and H2O are also needed.
   (iv) is the trap. The phase does NOT stop the instant light is removed. It keeps going for some time, because the ATP and NADPH already made are still there to be used up.

   So three are correct. This continuing-in-the-dark fact is the standard evidence that light is not needed by these steps themselves.

   The biosynthetic phase runs on stored ATP and NADPH, so it continues briefly after the light goes off. It follows the light rather than requiring it.

   NCERT Class 11 Biology, page 142

4. Q4 Multi-statement analysis

   In purple and green sulphur bacteria: (i) H2S is the hydrogen donor (ii) the oxidation product is sulphur or sulphate (iii) O2 is not released (iv) H2O is the hydrogen donor. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; H2O is the donor in GREEN PLANTS, so (iv) is wrong.

   What this is testing: which hydrogen donor belongs to which group of organisms.

   (i) is correct. Purple and green sulphur bacteria use H2S as the hydrogen donor.
   (ii) is correct. The oxidation product is sulphur or sulphate.
   (iii) is correct. These bacteria release no O2.
   (iv) is the trap. H2O is the hydrogen donor in GREEN PLANTS, which is exactly why plants give off oxygen and these bacteria give off sulphur instead.

   So three are correct. Van Niel used this very comparison to argue that the O2 of photosynthesis comes from water.

   Water for green plants, hydrogen sulphide for these bacteria. Oxygen is released only when the donor is water.

   NCERT Class 11 Biology, page 135

5. Q5 Multi-statement analysis

   Regarding electron movement in the ETS: (i) electrons pass to cytochromes (ii) this movement is downhill in terms of redox potential (iii) the electrons are not used up as they pass through the chain (iv) the electrons are consumed by the cytochromes. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; electrons are NOT used up but passed on to PS I, so (iv) is wrong.

   What this is testing: what happens to an electron as it moves down the transport chain.

   (i) is correct. The electrons are handed on to cytochromes.
   (ii) is correct. The movement is downhill in terms of redox potential, which is why energy is released along the way.
   (iii) is correct. The electrons themselves are not used up.
   (iv) is the trap, and it contradicts (iii). The cytochromes only pass the electron along; they hand it on to PS I, which needs it to replace the electron it lost to light.

   So three are correct. Carriers carry — they do not consume.

   Electrons pass through and are not consumed. The carriers are borrowed, never spent, which is what lets the chain run continuously.

   NCERT Class 11 Biology, page 139

6. Q6 Multi-statement analysis

   Causes of the proton gradient in the chloroplast: (i) splitting of water on the inner side releases protons into the lumen (ii) the primary acceptor transfers its electron to an H carrier that removes a proton from the stroma (iii) NADP reductase on the stroma side removes protons from the stroma (iv) protons are pumped out into the stroma. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; protons ACCUMULATE in the lumen, so (iv) is wrong.

   What this is testing: the three things that build the proton gradient, and its direction.

   (i) is correct. Water is split on the inner side of the membrane, so its protons are released into the lumen.
   (ii) is correct. The primary acceptor passes its electron to a hydrogen carrier that picks up a proton from the stroma.
   (iii) is correct. NADP reductase, on the stroma side, also removes protons from the stroma.
   (iv) is the trap. Protons build up IN THE LUMEN; the stroma is left short of them. The statement reverses the direction of the whole gradient.

   So three are correct.

   Protons enter the lumen from water splitting and from the carrier, and they are removed from the stroma by NADP reduction. Three contributions to one gradient.

   NCERT Class 11 Biology, page 141

7. Q7 Multi-statement analysis

   Chemiosmotic hypothesis in photosynthesis: (i) ATP synthesis is linked to development of a proton gradient across a membrane (ii) the membrane concerned is the thylakoid membrane (iii) proton accumulation is towards the inside, i.e., in the lumen (iv) in respiration protons accumulate in the intermembrane space of mitochondria. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.Three
   4. 4.FourCorrect answer

   Why option 4 is the answer

   The trap: All four are correct.

   What this is testing: the chemiosmotic hypothesis, and the parallel with respiration.

   All four are correct.
   (i) ATP synthesis is tied to a proton gradient across a membrane.
   (ii) In photosynthesis that membrane is the thylakoid membrane.
   (iii) Protons gather on the inside, in the thylakoid lumen.
   (iv) In respiration they gather in the intermembrane space of the mitochondrion.

   The same idea, two organelles. Learn the two destinations together — lumen in the chloroplast, intermembrane space in the mitochondrion — because questions often swap them.

   So all four are correct.

   Protons into the thylakoid lumen in photosynthesis, into the intermembrane space in respiration. Same mechanism, two organelles, opposite-facing compartments.

   NCERT Class 11 Biology, page 140

8. Q8 Multi-statement analysis

   Splitting of water: (i) is associated with PS II (ii) water is split into 2H+, [O] and electrons (iii) the water splitting complex is located on the inner side of the thylakoid membrane (iv) it is associated with PS I. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; water splitting is associated with PS II, not PS I, so (iv) is wrong.

   What this is testing: which photosystem splits water.

   (i) is correct. Water splitting is linked to PS II.
   (ii) is correct. Water yields 2H+, [O] and electrons.
   (iii) is correct. The water splitting complex sits on the inner side of the thylakoid membrane, which is why the protons land in the lumen.
   (iv) is the trap, and it contradicts (i). PS I does not split water; it takes its replacement electrons from the transport chain.

   So three are correct. Water goes with PS II, NADP+ with PS I.

   Water splitting belongs to PS II, on the inner face of the membrane. That location is why its protons land in the lumen and build the gradient.

   NCERT Class 11 Biology, page 139

9. Q9 Assertion and Reason

   AssertionThe pH of the thylakoid lumen decreases during the light reaction.

   ReasonChemiosmosis requires a membrane, a proton pump, a proton gradient and ATP synthase.

   1. 1.Both A and R are true and R is the correct explanation of A
   2. 2.Both A and R are true but R is not the correct explanation of ACorrect answer
   3. 3.A is true but R is false
   4. 4.A is false but R is true

   Why option 2 is the answer

   The trap: Both are true of photosynthetic chemiosmosis; the list of requirements is a parallel fact and does not explain the fall in lumen pH.

   What this is testing: whether the list of chemiosmosis requirements explains a fall in pH.

   A is true. The thylakoid lumen does become more acidic during the light reaction, because protons gather there.
   R is also true. Chemiosmosis does need a membrane, a proton pump, a proton gradient and ATP synthase.

   But R is a list of requirements, not a cause of the pH drop. So both are true and R does not explain A, giving code (2).

   The trap: R is a correct textbook sentence about the same process, which makes (1) attractive. A list of ingredients never counts as an explanation of one particular result.

   NCERT Class 11 Biology, page 141

10. Q10 Assertion and Reason

    AssertionThe Z scheme describes the electron path from PS II to NADP+.

    ReasonIn the electron transport system the electrons pass through a series of cytochromes.

    1. 1.Both A and R are true and R is the correct explanation of A
    2. 2.Both A and R are true but R is not the correct explanation of ACorrect answer
    3. 3.A is true but R is false
    4. 4.A is false but R is true

    Why option 2 is the answer

    The trap: Both are true of the light reaction; the cytochrome carriers are a parallel structural detail and do not explain the overall Z-shaped scheme.

    What this is testing: whether the cytochromes explain the shape of the Z scheme.

    A is true. The Z scheme traces the electron from PS II through to NADP+.
    R is true as well. The electrons do pass through a series of cytochromes on the way.

    But the cytochromes are one detail inside the path; they do not explain the overall Z-shaped scheme, which comes from the two uphill jumps driven by light. So both true, R not the explanation, code (2).

    The trap: R is true and clearly related, and relatedness feels like explanation. Ask whether R answers the question 'why', not merely 'what else is true here'.

    NCERT Class 11 Biology, page 139

11. Q11 Assertion and Reason

    AssertionChlorophyll a shows two absorption peaks in the visible spectrum.

    ReasonChlorophyll b, xanthophylls and carotenoids are called accessory pigments.

    1. 1.Both A and R are true and R is the correct explanation of A
    2. 2.Both A and R are true but R is not the correct explanation of ACorrect answer
    3. 3.A is true but R is false
    4. 4.A is false but R is true

    Why option 2 is the answer

    The trap: Both are true pigment facts running in parallel; the existence of accessory pigments does not explain the twin absorption peaks of chlorophyll a.

    What this is testing: whether accessory pigments explain the absorption peaks of chlorophyll a.

    A is true. Chlorophyll a shows two absorption peaks in the visible spectrum, in the blue region and in the red.
    R is true as well. Chlorophyll b, xanthophylls and carotenoids are indeed called accessory pigments.

    The two lines are separate pigment facts. Other pigments existing cannot explain why chlorophyll a itself absorbs where it does. So both true, R not the explanation, code (2).

    The trap: both lines come from the same page of the chapter, which makes them feel joined. Same topic is not the same as cause.

    NCERT Class 11 Biology, page 137

12. Q12 Assertion and Reason

    AssertionPhotosynthesis takes place only in the green parts of the plant.

    ReasonIn the leaf, the mesophyll cells contain a large number of chloroplasts.

    1. 1.Both A and R are true and R is the correct explanation of A
    2. 2.Both A and R are true but R is not the correct explanation of ACorrect answer
    3. 3.A is true but R is false
    4. 4.A is false but R is true

    Why option 2 is the answer

    The trap: Both are true; the abundance of chloroplasts in the mesophyll is a parallel fact and does not by itself explain why non-green parts cannot photosynthesise.

    What this is testing: whether chloroplast numbers in the mesophyll explain where photosynthesis happens.

    A is true. Photosynthesis takes place only in the green parts of the plant.
    R is true as well. The mesophyll cells of a leaf hold a large number of chloroplasts.

    But R only tells you why the leaf is a good site; it does not explain why non-green parts cannot photosynthesise. So both true, R not the explanation, code (2).

    The trap: R feels like the reason because green and chloroplasts belong together. An explanation of 'only the green parts' would have to say something about the parts that are not green.

    NCERT Class 11 Biology, page 136

13. Q13 Assertion and Reason

    AssertionThe Calvin cycle occurs in the stroma of the chloroplast.

    ReasonThe light reactions occur on the thylakoid membranes of the chloroplast.

    1. 1.Both A and R are true and R is the correct explanation of A
    2. 2.Both A and R are true but R is not the correct explanation of ACorrect answer
    3. 3.A is true but R is false
    4. 4.A is false but R is true

    Why option 2 is the answer

    The trap: Both are true statements of the division of labour within the chloroplast running in parallel; the site of the light reaction does not explain the site of the Calvin cycle.

    What this is testing: whether one half of the division of labour explains the other.

    A is true. The Calvin cycle runs in the stroma of the chloroplast.
    R is true as well. The light reactions run on the thylakoid membranes.

    The two lines describe the two halves of the same arrangement, side by side. Knowing where the light reaction happens does not explain why the Calvin cycle sits in the stroma. So both true, R not the explanation, code (2).

    The trap: the lines fit together so neatly that (1) looks obvious. Two matching facts are still two facts, not a cause and its effect.

    NCERT Class 11 Biology, page 136

14. Q14 Assertion and Reason

    AssertionThe oxygen evolved during photosynthesis in green plants comes from water and not from carbon dioxide.

    ReasonIn green plants water is the hydrogen donor and is oxidised to O2, as van Niel inferred from the sulphur bacteria that release sulphur instead when H2S is the donor.

    1. 1.Both A and R are true and R is the correct explanation of ACorrect answer
    2. 2.Both A and R are true but R is not the correct explanation of A
    3. 3.A is true but R is false
    4. 4.A is false but R is true

    Why option 1 is the answer

    The trap: R gives the comparative evidence that establishes water as the oxygen source.

    What this is testing: the evidence that photosynthetic oxygen comes from water.

    A is true. The O2 released by green plants comes from water, not from CO2.
    R is true and gives the evidence: in green plants water is the hydrogen donor and is oxidised to O2, while sulphur bacteria using H2S as the donor release sulphur instead.

    That comparison is exactly what van Niel used, so R explains A. Code (1).

    The trap: it feels natural that oxygen should come from carbon dioxide, since CO2 carries oxygen atoms. The donor molecule, not the carbon source, decides what is released.

    NCERT Class 11 Biology, page 135

15. Q15 Assertion and Reason

    AssertionPriestley concluded that plants restore to the air whatever breathing animals and burning candles remove.

    ReasonA candle burning in a closed bell jar soon gets extinguished and a mouse placed in it would suffocate.

    1. 1.Both A and R are true and R is the correct explanation of A
    2. 2.Both A and R are true but R is not the correct explanation of ACorrect answer
    3. 3.A is true but R is false
    4. 4.A is false but R is true

    Why option 2 is the answer

    The trap: Both are true observations of Priestley; the extinguishing of the candle is a parallel observation and is not the explanation of the restorative hypothesis.

    What this is testing: whether an observation counts as an explanation of a conclusion.

    A is true. Priestley did conclude that plants restore to the air what animals and candles remove.
    R is true too. A candle in a closed bell jar does go out, and a mouse there would suffocate.

    But R describes only the damage, not the restoring. What supports A is the further observation that a mint plant in the jar kept the candle burning and the mouse alive. So both true, R not the explanation, code (2).

    The trap: R is half of the experiment and so feels like the reason. The half that matters is the half with the plant in it.

    NCERT Class 11 Biology, page 134

16. Q16 Assertion and Reason

    AssertionChlorophyll a is regarded as the chief pigment of photosynthesis.

    ReasonA chromatographic separation of leaf pigments yields four pigments, of which chlorophyll a appears bright or blue green.

    1. 1.Both A and R are true and R is the correct explanation of A
    2. 2.Both A and R are true but R is not the correct explanation of ACorrect answer
    3. 3.A is true but R is false
    4. 4.A is false but R is true

    Why option 2 is the answer

    The trap: Both are true of chlorophyll a; its chromatographic colour is a parallel fact and does not establish its role as the chief pigment.

    What this is testing: whether a pigment's colour explains its importance.

    A is true. Chlorophyll a is the chief pigment of photosynthesis.
    R is true as well. A chromatogram of leaf pigments gives four pigments, and chlorophyll a is the bright or blue green band.

    But the colour of a band tells you nothing about the role of the pigment. Chlorophyll a is chief because it forms the reaction centre, not because of its shade. So both true, R not the explanation, code (2).

    The trap: R is a correct, vivid detail from the same page, and vividness is easy to mistake for relevance.

    NCERT Class 11 Biology, page 137

17. Q17 Assertion and Reason

    AssertionLight is rarely a limiting factor in nature.

    ReasonAn increase in incident light beyond a point causes the breakdown of chlorophyll.

    1. 1.Both A and R are true and R is the correct explanation of A
    2. 2.Both A and R are true but R is not the correct explanation of ACorrect answer
    3. 3.A is true but R is false
    4. 4.A is false but R is true

    Why option 2 is the answer

    The trap: Both are true of light as a factor; chlorophyll breakdown at very high light is a parallel effect and does not explain why light is seldom limiting.

    What this is testing: whether chlorophyll breakdown explains why light is seldom limiting.

    A is true. Light is rarely a limiting factor in nature.
    R is true as well. Very high light does cause the breakdown of chlorophyll.

    But chlorophyll breakdown at extreme light is a separate effect; it does not explain why light seldom limits the rate. The reason for A is that saturation is reached at about 10 per cent of full sunlight, so ordinary daylight is already more than enough. Both true, R not the explanation, code (2).

    The trap: both lines are about light, which makes them feel joined.

    NCERT Class 11 Biology, page 149

18. Q18 Statement I and Statement II

    Statement IIn the light harvesting complex all pigments except one chlorophyll a molecule form the antennae.

    Statement IIThe single chlorophyll a molecule forms the reaction centre.

    1. 1.Both Statement I and Statement II are correctCorrect answer
    2. 2.Both Statement I and Statement II are incorrect
    3. 3.Statement I is correct but Statement II is incorrect
    4. 4.Statement I is incorrect but Statement II is correct

    Why option 1 is the answer

    The trap: Both statements are correct.

    What this is testing: how a light harvesting complex is organised.

    Statement I says that in the LHC all the pigments except one chlorophyll a molecule form the antennae. Correct.
    Statement II says the single chlorophyll a molecule forms the reaction centre. Correct.

    Both correct, so the answer is (1).

    The two lines are the two halves of one picture: many pigment molecules gathering light like an aerial, and one special chlorophyll a at the centre where the energy is finally used. Nothing has been altered, so both stand.

    NCERT Class 11 Biology, page 138

19. Q19 Statement I and Statement II

    Statement IWater affects photosynthesis mainly through its effect on the plant rather than directly.

    Statement IIWater stress causes the stomata to close, reducing CO2 availability.

    1. 1.Both Statement I and Statement II are correctCorrect answer
    2. 2.Both Statement I and Statement II are incorrect
    3. 3.Statement I is correct but Statement II is incorrect
    4. 4.Statement I is incorrect but Statement II is correct

    Why option 1 is the answer

    The trap: Both statements are correct.

    What this is testing: how water acts on the rate of photosynthesis.

    Statement I says water affects photosynthesis mainly through its effect on the plant rather than directly. Correct.
    Statement II says water stress closes the stomata and so reduces CO2 availability. Correct.

    Both correct, so the answer is (1).

    Statement II is the mechanism behind Statement I: shortage of water shuts the stomata and makes the leaves wilt, cutting the supply of CO2 and the area of leaf. Water is a raw material too, but the chapter's point is that the indirect damage matters far more.

    NCERT Class 11 Biology, page 150

20. Q20 Statement I and Statement II

    Statement IPhotorespiration occurs in C4 plants but not in C3 plants.

    Statement IIIn C3 plants some O2 binds to RuBisCO, decreasing CO2 fixation.

    1. 1.Both Statement I and Statement II are correct
    2. 2.Both Statement I and Statement II are incorrect
    3. 3.Statement I is correct but Statement II is incorrect
    4. 4.Statement I is incorrect but Statement II is correctCorrect answer

    Why option 4 is the answer

    The trap: I incorrect (the reverse is true); II correct.

    What this is testing: which group of plants photorespires.

    Statement I says photorespiration occurs in C4 plants but not in C3 plants. Wrong — it is the other way round. C3 plants photorespire; C4 plants do not.
    Statement II says that in C3 plants some O2 binds to RuBisCO and so reduces CO2 fixation. Correct.

    So I incorrect, II correct, giving (4).

    The trap: Statement II gives the mechanism that shows Statement I is backwards. C3 plants expose RuBisCO to ordinary air, where O2 can compete; C4 plants surround the enzyme with concentrated CO2 so it cannot.

    NCERT Class 11 Biology, page 147

21. Q21 Match the columns

    Match the photorespiration feature with its state:

    Column I	Column II
    (a) Sugar synthesis	(iv) occurs
    (b) ATP synthesis	(ii) occurs
    (c) ATP utilisation	(iii) absent
    (d) CO2 release	(i) absent

    1. 1.(a)-(i), (b)-(iii), (c)-(iv), (d)-(ii)
    2. 2.(a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
    3. 3.(a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
    4. 4.(a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)Correct answer

    Why option 4 is the answer

    The trap: Photorespiration: no sugar, no ATP synthesis; ATP consumed and CO2 released.

    What this is testing: the balance sheet of photorespiration.

    No sugar is made and no ATP is made, while ATP is used up and CO2 is released. Option 4 sets those four out in order.

    Why option 3 is wrong: it says sugar synthesis occurs and ATP synthesis is absent, which would make photorespiration a partly useful pathway. Option 2 is wrong for the same kind of reason, since it has ATP synthesis occurring.

    The trap: the name sounds like respiration, which does yield ATP. Photorespiration yields nothing at all. Everything on its output side is a loss, which is why it is called wasteful.

    NCERT Class 11 Biology, page 147

22. Q22 Match the columns

    Match the leaf anatomy feature with the plant type:

    Column I	Column II
    (a) Kranz anatomy	(iii) C3 plants
    (b) Bundle sheath with many chloroplasts	(i) C3 plants
    (c) Calvin cycle in all mesophyll cells	(iv) C4 plants
    (d) Photorespiration present	(ii) C4 plants

    1. 1.(a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)
    2. 2.(a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
    3. 3.(a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)Correct answer
    4. 4.(a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)

    Why option 3 is the answer

    The trap: Kranz and chloroplast-rich bundle sheath-C4; Calvin in mesophyll and photorespiration-C3.

    What this is testing: sorting leaf features between C3 and C4 plants.

    Kranz anatomy and a bundle sheath packed with chloroplasts belong to C4 plants. The Calvin cycle running in all the mesophyll cells, and photorespiration being present, belong to C3 plants. That is option 3.

    Why option 2 is wrong: it makes a chloroplast-rich bundle sheath a C3 feature and the Calvin cycle in all mesophyll cells a C4 one — precisely the two facts that separate the groups.

    The trap: a C4 leaf does have mesophyll cells, but they fix CO2 with PEP carboxylase and never run the Calvin cycle. The cycle is kept in the bundle sheath.

    NCERT Class 11 Biology, page 148

23. Q23 Match the columns

    Match the pigment/system with its function:

    Column I	Column II
    (a) Accessory pigments	(iii) protect chlorophyll a from photo-oxidation
    (b) Chlorophyll a	(iv) light harvesting complex
    (c) Carotenoids	(ii) chief photosynthetic pigment
    (d) LHC	(i) transfer energy to chlorophyll a

    1. 1.(a)-(ii), (b)-(i), (c)-(iii), (d)-(iv)
    2. 2.(a)-(i), (b)-(iii), (c)-(ii), (d)-(iv)
    3. 3.(a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)
    4. 4.(a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)Correct answer

    Why option 4 is the answer

    The trap: Accessory pigments-energy transfer, Chl a-chief pigment, Carotenoids-photoprotection, LHC-light harvesting.

    What this is testing: the job of each pigment and of the LHC.

    Accessory pigments pass their absorbed energy to chlorophyll a, chlorophyll a is the chief photosynthetic pigment, carotenoids protect chlorophyll a from photo-oxidation, and LHC stands for light harvesting complex. That is option 4.

    Why the others are wrong: option 1 calls the accessory pigments the chief pigment and chlorophyll a an energy donor. Option 2 gives chlorophyll a the protective role. Option 3 defines accessory pigments as the light harvesting complex.

    The trap: accessory does not mean unimportant. These pigments both widen the range of light caught and shield the main pigment.

    NCERT Class 11 Biology, page 138

24. Q24 Match the columns

    Match the requirement of chemiosmosis with its role:

    Column I	Column II
    (a) Membrane	(iii) synthesises ATP
    (b) Proton pump	(i) stores the energy
    (c) Proton gradient	(ii) creates the gradient
    (d) ATP synthase	(iv) thylakoid membrane

    1. 1.(a)-(iv), (b)-(ii), (c)-(i), (d)-(iii)Correct answer
    2. 2.(a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)
    3. 3.(a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
    4. 4.(a)-(iii), (b)-(ii), (c)-(i), (d)-(iv)

    Why option 1 is the answer

    The trap: Membrane, pump, gradient and ATP synthase are the four requirements of chemiosmosis.

    What this is testing: the four requirements of chemiosmosis and what each contributes.

    The membrane is the thylakoid membrane, the proton pump creates the gradient, the gradient stores the energy, and ATP synthase makes the ATP. That is option 1.

    Why the others are wrong: option 2 exchanges the first two, so the membrane creates the gradient and the pump becomes the thylakoid membrane. Option 3 says the pump stores the energy and the gradient creates the gradient. Option 4 makes the membrane the ATP-making part.

    The trap: all four items are genuine requirements, so only the roles can be tested. Follow the order of events: pump, gradient, synthase.

    NCERT Class 11 Biology, page 142

25. Q25 Exception / incorrect

    Identify the INCORRECT pairing (compound – carbon number):

    1. 1.RuBP – 5 carbons
    2. 2.OAA – 3 carbonsCorrect answer
    3. 3.PEP – 3 carbons
    4. 4.PGA – 3 carbons

    Why option 2 is the answer

    The trap: OAA is a four-carbon acid.

    What this is testing: the carbon count of four molecules from the two pathways.

    RuBP with 5 carbons is correct. PEP with 3 is correct. PGA with 3 is correct. OAA with 3 carbons is WRONG — OAA has FOUR.

    So the incorrect pairing is OAA and three carbons.

    The trap: three of the four entries carry the number three, so the eye stops checking by the time it reaches the last one. OAA is the first product of the C4 pathway, and the pathway is named after its four carbons.

    NCERT Class 11 Biology, page 146

26. Q26 Exception / incorrect

    Identify the INCORRECT pairing (plant type – temperature optimum):

    1. 1.C4 plants – 30-40°C
    2. 2.C3 plants – 20-25°C
    3. 3.tropical plants – higher optimum
    4. 4.C3 plants – above 40°CCorrect answer

    Why option 4 is the answer

    The trap: C3 plants have a much lower temperature optimum.

    What this is testing: which plant group prefers which temperature.

    The pairing 'C3 plants - above 40°C' is the wrong one. C3 plants have a much lower optimum, about 20-25°C. It is C4 plants that go on working well at high temperatures.

    Why the other pairings are right: C4 plants do best at about 30-40°C, C3 plants at about 20-25°C, and tropical plants have a higher optimum than temperate ones.

    The trap: options 2 and 4 both begin 'C3 plants' and give opposite temperatures, which marks one of them as planted. Tie the groups to their homes: C4 crops are tropical and heat-loving, C3 crops are temperate.

    NCERT Class 11 Biology, page 150

27. Q27 Sequence / ordering

    Correct order of increasing carbon number:

    1. 1.RuBP → PGA → OAA
    2. 2.PGA (3C) → OAA (4C) → RuBP (5C)Correct answer
    3. 3.OAA → RuBP → PGA
    4. 4.RuBP → OAA → PGA

    Why option 2 is the answer

    The trap: PGA has 3 carbons, OAA 4 and RuBP 5.

    What this is testing: the carbon count of three molecules that are constantly confused.

    PGA has 3 carbons, OAA has 4 and RuBP has 5. In increasing order that is PGA, OAA, RuBP, which is option 2.

    Why the others are wrong: options 1 and 4 start with RuBP, the largest, so they run downwards or out of order. Option 3 puts OAA ahead of the smaller PGA.

    The trap: only one option shows the numbers, and students distrust an option that looks too helpful. Tie each molecule to its pathway: PGA the 3-carbon product of C3, OAA the 4-carbon product of C4, RuBP the 5-carbon acceptor.

    NCERT Class 11 Biology, page 146

28. Q28 NEET 2026 (Re-Exam)

    Select the correct sequence of experiments that led to the understanding of photosynthesis:

    1. 1.Role of air → release of oxygen → production of glucose → absorption spectraCorrect answer
    2. 2.Absorption spectra → glucose → oxygen → role of air
    3. 3.Release of oxygen → glucose → absorption spectra → role of air
    4. 4.Production of glucose → role of air → release of oxygen → absorption spectra

    Why option 1 is the answer

    The trap: Historically, the role of air was studied first, followed by oxygen release, glucose production, and finally the absorption spectra of pigments.

    What this is testing: the order in which the big findings arrived.

    Option 1 has it: the role of air was studied first, then the release of oxygen, then the production of glucose, and last the absorption spectra of the pigments.

    Why the others are wrong: options 2 and 3 put the spectra early, but the pigment work came at the end of this sequence. Option 4 begins with glucose, which was shown only after the gas experiments.

    The trap: the options shuffle four genuine findings, so each looks plausible alone. Anchor the two ends - air first, spectra last - and the middle sorts itself out.

    NCERT Class 11 Biology, page 133

29. Q29 NEET 2026 (Cancelled)

    The number of ATP and NADPH molecules required to make one molecule of glucose through the Calvin pathway is:

    1. 1.12 ATP and 18 NADPH
    2. 2.6 ATP and 4 NADPH
    3. 3.24 ATP and 16 NADPH
    4. 4.18 ATP and 12 NADPHCorrect answer

    Why option 4 is the answer

    The trap: Six turns of the Calvin cycle, needed for one glucose, consume 18 ATP and 12 NADPH.

    What this is testing: both totals for one glucose at once.

    Six turns of the Calvin cycle make one glucose, and each turn costs 3 ATP and 2 NADPH. Six threes give 18 ATP; six twos give 12 NADPH.

    Why the others are wrong: option 1 carries the right two numbers with the labels swapped, which is the commonest slip. Options 2 and 3 give totals this arithmetic never produces.

    The trap: option 1 exists only to catch a reversed pair. Do the multiplication instead of trusting recall, and the larger total always lands on ATP.

    NCERT Class 11 Biology, page 142

30. Q30 NEET 2024 (Re-Exam)

    The number of ATP and NADPH molecules required for every CO2 fixed in the Calvin cycle is:

    1. 1.2 ATP and 3 NADPH
    2. 2.3 ATP and 2 NADPHCorrect answer
    3. 3.6 ATP and 4 NADPH
    4. 4.1 ATP and 1 NADPH

    Why option 2 is the answer

    The trap: Fixation of one CO2 in the Calvin cycle consumes 3 ATP and 2 NADPH.

    What this is testing: the cost of one CO2 in both currencies.

    Fixing one CO2 in the Calvin cycle uses 3 ATP and 2 NADPH.

    Why the others are wrong: option 1 offers the same two numbers with the labels swapped. Option 3 doubles both figures, which is the cost of two CO2, not one. Option 4 is a pair that appears nowhere in the cycle.

    The trap: option 1 is built entirely out of the reversal. Say it as one fixed phrase every time - three ATP, two NADPH - so the order cannot come apart under pressure.

    NCERT Class 11 Biology, page 142