25 questions in 25 minutes on the NTA computer-based test interface, all from Photosynthesis in Higher Plants. +4 / -1 marking, instant score, full solutions. Free, no login.
A chapter test is the fastest honest check on whether a chapter has actually landed. This one draws 25 questions from Photosynthesis in Higher Plants, of which 17 are real NEET previous-year questions and 6 sit at the harder end of the bank. Sit it in one 25-minute block, the way you would in the hall.
Revising first? Read the Photosynthesis in Higher Plants chapter notes, then come back and take this test to check it stuck.
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Duration: 180 minutes · 180 questions · 720 marks maximum
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NEET CBT mock test: common questions
How many questions are in this Photosynthesis in Higher Plants mock test?
25 questions in 25 minutes, marked +4 for a correct answer and -1 for a wrong one, exactly like the real paper. 17 of them are NEET previous-year questions.
Is this the same interface as the real NEET CBT?
Yes. On-screen countdown, colour-coded question palette, Save & Next, Clear Response and Mark for Review, then an instant score with full solutions.
Should I take this before or after revising Photosynthesis in Higher Plants?
Both, and that is the point. Take it cold to find out what you actually do not know, revise from the chapter notes, then retake it to confirm the gap closed.
All 25 questions with answers and solutions
The complete paper in text form, with the correct option and a worked explanation for every question. Sit the timed test above first: the score is only worth having if you earn it. Then open this to revise, or to re-read a question you got wrong without replaying the whole paper.
Show all 25 questions with answers and solutions
Botany
- Q1Why do C4 plants lack significant photorespiration?
- They lack RuBisCO entirely
- They do not perform the Calvin cycle
- Their stomata are always closed
- CO2 is concentrated around RuBisCO in bundle-sheath cells, favouring carboxylation over oxygenation
Answer: (D) CO2 is concentrated around RuBisCO in bundle-sheath cells, favouring carboxylation over oxygenation
The C4 pathway pumps CO2 into bundle-sheath cells, keeping the CO2 concentration high around RuBisCO. This suppresses RuBisCO’s oxygenase activity, so photorespiration is minimal and productivity is high.
- Q2How many ATP and NADPH molecules are required to fix ONE molecule of CO2 in the Calvin cycle?
- 18 ATP and 12 NADPH
- 1 ATP and 1 NADPH
- 3 ATP and 2 NADPH
- 2 ATP and 3 NADPH
Answer: (C) 3 ATP and 2 NADPH
Per CO2 fixed, the Calvin cycle uses 3 ATP and 2 NADPH. For one glucose (6 CO2) this scales to 18 ATP and 12 NADPH.
- Q3The first stable product of CO2 fixation in the Calvin cycle is:
- Phosphoenolpyruvate (3-C)
- RuBP (5-C)
- Oxaloacetic acid (4-C)
- 3-phosphoglyceric acid (3-C)
Answer: (D) 3-phosphoglyceric acid (3-C)
In the C3 pathway, RuBisCO adds CO2 to RuBP to form two molecules of the 3-carbon 3-phosphoglyceric acid (3-PGA), the first stable product.
- Q4Photochemical reactions in the chloroplast are directly involved in:
- Fixation of carbon dioxide
- Photolysis of water and phosphorylation of ADP to ATP
- Formation of phosphoglyceric acid
- Synthesis of glucose and starch
Answer: (B) Photolysis of water and phosphorylation of ADP to ATP
The photochemical (light) reactions directly carry out photolysis of water and the phosphorylation of ADP to ATP (plus NADP+ reduction). PGA formation, CO2 fixation and glucose/starch synthesis are dark-reaction events that do not directly require light.
- Q5In the sugarcane plant, 14CO2 is fixed in malic acid, in which the enzyme that fixes CO2 is:
- Ribulose bisphosphate carboxylase
- Fructose phosphatase
- Ribulose phosphate kinase
- Phosphoenol pyruvic acid carboxylase
Answer: (D) Phosphoenol pyruvic acid carboxylase
Sugarcane is a C4 plant; the CO2 taken up to form OAA/malic acid in mesophyll cells is fixed onto PEP by phosphoenol pyruvate carboxylase (PEPcase). RuBP carboxylase acts later in bundle-sheath cells in the Calvin cycle.
- Q6Kranz anatomy is typical of:
- CAM plants
- C4 plants
- C3 plants
- C2 plants
Answer: (B) C4 plants
Kranz (‘wreath’) anatomy, with bundle-sheath cells arranged in concentric layers around the vascular bundles, is characteristic of C4 plants such as maize and sugarcane. It enables CO2 concentration around RuBisCO in the bundle sheath.
- Q7The oxygen released during photosynthesis comes from:
- Glucose
- Carbon dioxide
- Water
- Atmospheric O2
Answer: (C) Water
Photolysis of water (2H2O -> 4H+ + O2 + 4e-) associated with PS II splits water to release O2. Isotope studies confirm the O2 evolved originates from water, not CO2.
- Q8In Engelmann’s classic experiment, a filamentous green alga (Cladophora) was placed in a suspension of aerobic bacteria and illuminated with light split by a prism. The bacteria accumulated mainly in the regions of:
- Blue and red light
- Orange and yellow light
- Violet and green light
- Indigo and green light
Answer: (A) Blue and red light
Engelmann used aerobic bacteria as O2 indicators. They crowded where photosynthesis (and hence O2 release) was greatest, i.e. in the blue (violet-blue) and red regions where chlorophyll a absorbs most strongly. This gave the first action spectrum of photosynthesis, so the answer is blue and red, not green/yellow (poorly absorbed).
- Q9The substrate for photorespiration is:
- Glycine
- Glycolate
- Serine
- Ribulose bisphosphate
Answer: (B) Glycolate
Photorespiration is the oxidation of a 2-carbon photosynthetic intermediate, glycolate (glycolic acid), formed when RuBisCO oxygenates RuBP. Glycolate is shuttled through peroxisomes and mitochondria; it is the recognised substrate of the photorespiratory pathway.
- Q10Plants adapted to low light intensity have:
- Higher rate of CO2 fixation than sun plants
- More extended root system
- Leaves modified to spines
- Larger photosynthetic unit size than sun plants
Answer: (D) Larger photosynthetic unit size than sun plants
Shade-tolerant (low-light) plants have a LARGER photosynthetic unit size (more antenna pigments per reaction centre) to harvest scarce light efficiently, but lower overall photosynthetic and growth rates than sun plants. CO2 fixation rate is not higher, and root/spine changes are unrelated.
- Q11In C3 plants, the first CO2 acceptor (acceptor molecule) of the Calvin cycle is:
- Ribulose 1,5-bisphosphate (RuBP)
- Phosphoenol pyruvate (PEP)
- Phosphoglyceric acid (PGA)
- Ribulose monophosphate
Answer: (A) Ribulose 1,5-bisphosphate (RuBP)
In C3 plants the CO2 acceptor is the 5-carbon ribulose 1,5-bisphosphate (RuBP); RuBisCO adds CO2 to it to form two molecules of 3-PGA. PEP is the acceptor in C4 plants, and PGA is the product, not the acceptor.
- Q12In photosystem-I, the first (primary) electron acceptor is:
- Ferredoxin
- Cytochrome
- An iron-sulphur protein
- Plastocyanin
Answer: (C) An iron-sulphur protein
In PS-I the primary electron acceptor is an iron-sulphur (Fe-S) protein, which then passes electrons on to ferredoxin and finally to NADP+. Plastocyanin donates electrons INTO PS-I, and ferredoxin is a later (secondary) acceptor, so the primary acceptor is the Fe-S protein.
- Q13Emerson’s enhancement effect and the red drop were instrumental in the discovery of:
- Oxidative phosphorylation
- Photophosphorylation and non-cyclic electron transport
- Photophosphorylation and cyclic electron transport
- Two photosystems operating simultaneously
Answer: (D) Two photosystems operating simultaneously
Emerson observed a sharp drop in yield beyond 680 nm (red drop) and an enhancement when 680 nm and 700 nm light were given together. This proved that two distinct photosystems (PS-I and PS-II) operate together in photosynthesis.
- Q14In the Hatch and Slack pathway, the primary CO2 acceptor is:
- Phosphoenol pyruvate (PEP)
- RuBP
- Phosphoglyceric acid
- Oxaloacetic acid
Answer: (A) Phosphoenol pyruvate (PEP)
The Hatch-Slack (C4) pathway operates in mesophyll cells where the primary CO2 acceptor is the 3-carbon phosphoenol pyruvate (PEP); CO2 + PEP gives the 4-carbon OAA. RuBP is the acceptor in the C3/Calvin cycle, and OAA is the product, not the acceptor.
- Q15The first acceptor of electrons from an excited chlorophyll molecule of photosystem-II is:
- Iron-sulphur protein
- Cytochrome
- Quinone (plastoquinone)
- Ferredoxin
Answer: (C) Quinone (plastoquinone)
Plastoquinone (a quinone) is the first stable electron acceptor from the excited reaction centre P680 of photosystem-II. Ferredoxin and iron-sulphur proteins act on the PS-I side; cytochrome b6f comes after plastoquinone.
- Q16At a temperature above 35 degrees C, during photosynthesis and respiration in a plant:
- Rate of photosynthesis will decline earlier than that of respiration
- There is no fixed pattern
- Both decline simultaneously
- Rate of respiration will decline earlier than that of photosynthesis
Answer: (A) Rate of photosynthesis will decline earlier than that of respiration
The optimum temperature for photosynthesis (~10-25 C in C3 plants) is lower than that for respiration (~20-30 C). So above ~35 C photosynthesis declines earlier (sooner) than respiration, which has a higher temperature optimum and falls off later.
- Q17In photosynthesis, energy from the light reaction is transferred to the dark reaction in the form of:
- Chlorophyll
- ADP
- ATP (and NADPH)
- RuDP
Answer: (C) ATP (and NADPH)
The light reaction stores captured energy as ATP and NADPH (‘assimilatory power’), which are then used by the dark reaction to reduce CO2 to carbohydrate. ADP and RuBP are reactants regenerated, not the energy carriers transferred.
- Q18Maximum rate of photosynthesis occurs in which regions of the visible spectrum?
- Only green
- Orange and green
- Blue and red
- Green and yellow
Answer: (C) Blue and red
Chlorophyll a absorbs maximally in the blue-violet and red regions; therefore photosynthesis is highest in blue and red light and least in the green region (green is mostly reflected).
- Q19In the Z-scheme of electron flow, the correct sequence of electron carriers is:
- Water -> PS II -> cyt b6f -> PS I -> NADP
- PS I -> PS II -> NADP
- PS II -> NADP -> PS I -> water
- Water -> PS I -> PS II -> NADP
Answer: (A) Water -> PS II -> cyt b6f -> PS I -> NADP
Electrons flow from water to PS II, then through plastoquinone and the cytochrome b6f complex and plastocyanin to PS I, and finally via ferredoxin to NADP+. PS II precedes PS I despite its higher number.
- Q20The reaction centre of Photosystem I absorbs light maximally at:
- 550 nm
- 680 nm
- 490 nm
- 700 nm
Answer: (D) 700 nm
PS I has reaction centre P700, absorbing maximally at 700 nm; PS II has P680, absorbing at 680 nm.
- Q21Stroma lamellae differ from grana thylakoids in that stroma lamellae:
- Contain no pigments
- Are the site of carbon fixation
- Contain PS II but lack PS I
- Lack PS II and NADP reductase
Answer: (D) Lack PS II and NADP reductase
Stroma lamellae lack PS II and NADP reductase, so they carry out only cyclic photophosphorylation (PS I only), whereas grana thylakoids have both photosystems for non-cyclic flow.
- Q22NADPH is generated through:
- Glycolysis
- Photosystem-I
- Anaerobic respiration
- Photosystem-II
Answer: (B) Photosystem-I
NADPH is formed at the end of the non-cyclic electron-transport chain on the PS-I side: ferredoxin (reduced by PS-I) passes electrons via NADP reductase to NADP+, reducing it to NADPH. Water splitting and proton release are linked to PS-II, but the actual reduction of NADP+ is downstream of PS-I.
- Q23PGA as the first CO2-fixation product of photosynthesis was discovered in:
- Alga
- Gymnosperm
- Angiosperm
- Bryophyte
Answer: (A) Alga
Melvin Calvin used radioactive 14C in the alga Chlorella to trace CO2 fixation and found the first stable product to be the 3-carbon 3-phosphoglyceric acid (PGA). The work was done in an alga, not a bryophyte/gymnosperm/angiosperm.
- Q24The stroma in the chloroplasts of higher plants contains:
- Enzymes of the light-independent (dark) reaction
- Ribosomes only
- Chlorophyll
- Enzymes of the light-dependent reaction
Answer: (A) Enzymes of the light-independent (dark) reaction
The stroma is the fluid matrix where the Calvin cycle runs, so it holds the light-independent (dark-reaction) enzymes such as RuBisCO. The light-dependent reaction and chlorophyll are on the grana/thylakoid membranes, not free in the stroma.
- Q25In the leaves of C4 plants, malic acid formation during CO2 fixation occurs in the cells of the:
- Phloem
- Epidermis
- Bundle sheath
- Mesophyll
Answer: (D) Mesophyll
In C4 leaves, CO2 is first fixed in the mesophyll cells: OAA formed there is reduced to malic acid in the mesophyll. The malic acid then moves to bundle-sheath cells where it is decarboxylated to release CO2 for the Calvin cycle.