Photosynthesis in Higher PlantsNEET MCQs with solutions
Photosynthesis in Higher Plants covers the classic experiments, the pigments, the light reaction and the ways plants fix carbon — the Calvin cycle, the C4 pathway and photorespiration. NEET questions test scientists and their experiments, the Z-scheme, and exactly where each step happens.
- Class
- 11 Biology
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- 24 questions
- In the RankUp app
- 440 questions
- ELITE questions
- 43
- NCERT topics
- 8
Practise 24 questions
Tap an option to check it. Questions from every NCERT topic in this chapter, from easy to hard.
Q1Introduction to Photosynthesis
The green colour of leaves is due to:
Not quite — the answer is D.
Chlorophyll absorbs red (660–700 nm) and blue (430–450 nm) wavelengths most efficiently and reflects green wavelengths, which we perceive as the leaf colour. It does not absorb green light — absorption of green would make leaves appear red or blue.
Q2Introduction to Photosynthesis
Which of the following correctly pairs an organism with the type of photosynthesis it performs?
Not quite — the answer is C.
Green plants and cyanobacteria perform oxygenic photosynthesis using water as hydrogen donor, releasing O₂. Purple and green sulphur bacteria perform anoxygenic photosynthesis using H₂S, releasing sulphur instead of oxygen.
Q3Introduction to Photosynthesis
In the light reactions of photosynthesis, the immediate (terminal) electron acceptor from PS I is:
Not quite — the answer is B.
In non-cyclic photophosphorylation, electrons from PS I are passed via ferredoxin to NADP⁺ reductase, which reduces NADP⁺ to NADPH. NADP⁺ is the terminal electron acceptor, not CO₂ (which is reduced later in the stroma using NADPH).
Q4Early Experiments
Ingenhousz also showed that oxygen evolution occurs mainly from:
Not quite — the answer is D.
Oxygen was evolved only from green (chlorophyll-containing) parts of the plant exposed to light — non-green parts such as roots, stems, and flowers did not release O₂.
Q5Early Experiments
The first action spectrum of photosynthesis was experimentally demonstrated by:
Not quite — the answer is C.
Engelmann's 1883 experiment split light with a prism onto Cladophora and used aerobic bacteria as O₂ sensors, producing the first action spectrum. Julius von Sachs demonstrated starch production — a common mix-up trap.
Q6Early Experiments
The "Red Drop" phenomenon, where photosynthetic efficiency drops sharply beyond 680 nm wavelength, was observed by:
Not quite — the answer is C.
Emerson observed that quantum yield of photosynthesis drops dramatically when wavelength exceeds 680 nm (far-red) — the "Red Drop." This led to his discovery of the Emerson Enhancement Effect and the concept of two photosystems.
Q7Site of Photosynthesis
A stack of thylakoids within the chloroplast is termed:
Not quite — the answer is D.
A granum (plural: grana) is a stack of thylakoid discs. Stroma is the surrounding matrix; cisterna is a Golgi term; matrix is the mitochondrial equivalent of stroma — all serve as effective distractors.
Q8Site of Photosynthesis
The internal aqueous space enclosed within the thylakoid membrane is called the:
Not quite — the answer is B.
The thylakoid lumen is the space enclosed within the thylakoid membrane. It is distinct from the stroma (which surrounds grana) and the intermembrane space (between the two envelope membranes).
Q9Site of Photosynthesis
The DNA found within chloroplasts is best described as:
Not quite — the answer is B.
Chloroplast DNA is circular and histone-free, closely resembling prokaryotic (bacterial) DNA — supporting the endosymbiotic theory. Option A describes eukaryotic nuclear DNA; Option C is a trap referencing viral nucleic acids.
Q10Pigments Involved in Photosynthesis
The reaction centre chlorophyll of Photosystem II, which drives water splitting, is designated as:
Not quite — the answer is A.
PS II reaction centre is P680, absorbing maximally at 680 nm and providing the energy to oxidise water. P700 is PS I. P660 and P640 are not recognised reaction centre designations in NCERT.
Q11Pigments Involved in Photosynthesis
Which carotenoid pigment is orange in colour and protects chlorophyll from photooxidative damage?
Not quite — the answer is D.
β-Carotene is the orange-coloured carotenoid that quenches singlet oxygen and dissipates excess excitation energy, protecting the photosynthetic apparatus from photooxidative damage. Xanthophylls are yellow, not orange. Phycocyanin is a phycobilin found in cyanobacteria.
Q12Pigments Involved in Photosynthesis
The action spectrum of photosynthesis is broader than the absorption spectrum of purified chlorophyll a because:
Not quite — the answer is D.
The action spectrum includes contributions from chlorophyll b, carotenoids, and xanthophylls — all of which absorb wavelengths that purified chlorophyll a does not, and transfer that energy to the reaction centre, making photosynthesis effective across a wider spectrum.
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Get RankUp on Google PlayQ13Light Reaction
The reducing power generated during non-cyclic photophosphorylation, used directly in the Calvin cycle, is in the form of:
Not quite — the answer is C.
NADPH provides the reducing equivalents (electrons + protons) required to reduce 3-PGA to G3P in the Calvin cycle. ATP provides energy but not electrons. O₂ is a byproduct, not used in carbon fixation. Glucose is produced in the Calvin cycle, not the light reactions.
Q14Light Reaction
The non-cyclic electron flow from PS II to PS I via electron carriers, when plotted on a redox potential scale, is called the:
Not quite — the answer is B.
The Z-scheme (named by Hill and Bendall) describes the energetics of non-cyclic electron flow — when plotted with redox potential on the Y-axis, the path from water through PS II, electron carriers, and PS I to NADP⁺ traces a Z-shaped curve.
Q15Light Reaction
Cyclic photophosphorylation exclusively involves:
Not quite — the answer is C.
Cyclic photophosphorylation involves only PS I — electrons excited from P700 pass to ferredoxin, then cycle back through the Cyt b6f complex and plastocyanin to P700 itself. No PS II, no water splitting, no NADPH production — only ATP is generated.
Q16C4 Pathway
In C4 plants, the initial fixation of atmospheric CO₂ by PEP carboxylase occurs in:
Not quite — the answer is C.
PEP carboxylase is localised exclusively in mesophyll cells. It fixes CO₂ into OAA, which is converted to malate and transported to bundle sheath cells. Bundle sheath cells receive CO₂ indirectly via malate decarboxylation, not directly from atmosphere.
Q17C4 Pathway
The enzyme responsible for primary CO₂ carboxylation in mesophyll cells of C4 plants is:
Not quite — the answer is D.
PEP carboxylase catalyses CO₂ fixation to PEP in mesophyll cells. Crucially, RuBisCO is present only in bundle sheath cells in C4 plants — not in mesophyll. This reciprocal distribution (PEP carboxylase in mesophyll, RuBisCO in bundle sheath) is a frequent NEET trap.
Q18C4 Pathway
The chloroplasts of bundle sheath cells in C4 plants characteristically:
Not quite — the answer is D.
Bundle sheath chloroplasts are agranal (lacking stacked grana) — they are specialised for the Calvin cycle (stroma reactions) rather than light reactions. The absence of grana reflects reduced PS II activity and minimal light reaction function in these cells.
Q19Photorespiration
The 2-phosphoglycolate formed by RuBisCO oxygenase activity contains how many carbon atoms?
Not quite — the answer is D.
2-phosphoglycolate is a 2-carbon compound — the phosphate group does not contribute carbon atoms. It cannot enter the Calvin cycle directly (which requires 3C or 5C intermediates) and must be metabolised through the costly photorespiratory C2 pathway.
Q20Photorespiration
In the peroxisome, glycolate is oxidised to glyoxylate, which is then transaminated to form:
Not quite — the answer is B.
Glyoxylate is transaminated (amino group added) to form glycine in the peroxisome. Glycine then moves to the mitochondria. Serine is formed later in mitochondria from two glycine molecules — not in the peroxisome.
Q21Photorespiration
In the mitochondria during photorespiration, two molecules of glycine are converted to:
Not quite — the answer is C.
Two glycine molecules (2×2C = 4C) are converted to one serine (3C) + one CO₂ + one NH₃ by the glycine decarboxylase complex in mitochondria. This is the step where photorespiratory CO₂ is released. NH₃ is subsequently reassimilated in the chloroplast — it is released, not retained.
Q22Factors Affecting Photosynthesis
Which of the following is correctly classified as an internal (plant) factor affecting photosynthesis?
Not quite — the answer is D.
Internal factors are intrinsic to the plant — chlorophyll content, leaf anatomy, leaf age, and enzyme concentration. Light intensity, CO₂ concentration, and temperature are all external (environmental) factors. This classification is directly from NCERT.
Q23Factors Affecting Photosynthesis
Temperature primarily affects photosynthesis by directly influencing:
Not quite — the answer is D.
The dark reactions (Calvin cycle) are enzyme-mediated and highly temperature-sensitive (Q₁₀ ≈ 2). Light reactions are photochemical and relatively temperature-independent. RuBisCO and other Calvin cycle enzymes show optimal activity within a specific temperature range and are denatured at high temperatures.
Q24Factors Affecting Photosynthesis
At very high light intensities, photosynthetic rate may decline because:
Not quite — the answer is A.
Excess light energy exceeds the capacity of photoprotective mechanisms (carotenoids, xanthophyll cycle), leading to photooxidative damage to chlorophyll — a process called photoinhibition. Option C is a trap: RuBisCO is not directly light-inhibited; it is indirectly affected via substrate supply.
ELITE question · AIR under 50 level
This chapter has 43 ELITE questions for students aiming at the very top. They are only in the app.
Unlock ELITE questions in the appPhotosynthesis facts to remember
Quick revision: most questions in this chapter test these facts.
| Topic | Key fact |
|---|---|
| Joseph Priestley (1770) | Candle, mouse and mint plant in a bell jar — plants restore the air |
| Jan Ingenhousz | Sunlight is essential; only green parts release oxygen |
| Julius von Sachs (1854) | Green parts make glucose, stored as starch; chlorophyll is in chloroplasts |
| T.W. Engelmann | First action spectrum using a prism, Cladophora and aerobic bacteria — blue and red regions |
| Cornelius van Niel | Oxygen released in photosynthesis comes from water, not CO₂ |
| Pigments | Chlorophyll a (bright or blue-green), chlorophyll b (yellow-green), xanthophylls (yellow), carotenoids (yellow to orange) |
| Reaction centres | PS I: P700; PS II: P680 |
| Splitting of water | Linked to PS II, on the inner side of the thylakoid; releases H⁺, O₂ and electrons |
| Z-scheme | Non-cyclic electron flow PS II → PS I → NADP⁺; cyclic flow uses PS I only and makes ATP, no NADPH |
| Chemiosmosis | Protons build up in the thylakoid lumen; ATP synthase (CF₀–CF₁) makes ATP |
| Calvin cycle | Carboxylation (RuBisCO), reduction, regeneration; one glucose needs 6 turns, 18 ATP and 12 NADPH |
| C4 pathway (Hatch–Slack) | Kranz anatomy; PEP carboxylase in mesophyll; first product oxaloacetic acid (4C); e.g. maize, sorghum |
| Photorespiration | RuBisCO acts as oxygenase in C3 plants; no ATP or NADPH made; absent in C4 plants |
| Law of limiting factors | Blackman (1905) |
What the app covers in this chapter
440 questions in total, each with a detailed explanation.
| Introduction to Photosynthesis | 20 |
| Early Experiments | 20 |
| Site of Photosynthesis | 20 |
| Pigments Involved in Photosynthesis | 20 |
| Light Reaction | 21 |
| C4 Pathway | 20 |
| Photorespiration | 20 |
| Factors Affecting Photosynthesis | 20 |
| Mixed practice and chapter tests | 279 |
Questions students ask
Is Photosynthesis in Higher Plants important for NEET?
Yes. It is one of the highest-yield Botany chapters. Questions come from the early experiments, pigments and photosystems, the Z-scheme, the Calvin cycle and the difference between C3 and C4 plants.
Which topics should I revise first?
Start with the scientists and their experiments, then the light reaction (photosystems, water splitting, Z-scheme), and finally the Calvin cycle, C4 pathway and photorespiration (use the table on this page).
How many questions from this chapter are on RankUp?
The RankUp app has 440 questions on Photosynthesis in Higher Plants, including 43 ELITE questions written for students aiming at AIR under 50. Every question has a detailed explanation.
Can I download these questions as a PDF?
Yes. The free PDF on this page has all 24 questions with the answer key and explanations. No signup is needed.
