NEET BotanyUpdated 19 Oct 2026

Photosynthesis in Higher Plants: NEET PYQs and weightage

Photosynthesis in Higher Plants carries 4.3 of 100 Botany marks in NEET by past-paper share: 34 of the 793 tagged NEET Botany PYQs in the ViJEEta bank (NEET 2013–2026). It ranks 12 of 21 Botany chapters.

Take the 25-question Photosynthesis in Higher Plants test Key facts ↓All NEET Botany chapters

4.3/100 Weight in Botany

Exam importance (3/5, by past-paper share)

34 NEET PYQs

483 Practice questions

406 With measured difficulty

How the weight is computed: this chapter's tagged NEET PYQs divided by all tagged NEET Botany PYQs in the bank (34 of 793), times 100, with repeated questions counted once. The bank does not store the year of each NEET question, so none is printed. Computed from the bank at build time. Updated 19 Oct 2026.

Photosynthesis in Higher Plants: key facts for NEET

16 facts the paper keeps asking, each with how it is asked. Copy it onto one page of your notebook: that page is this chapter's handbook.

Priestley (1770)
A mint plant in a bell jar kept the candle burning and the mouse alive, so plants restore the air.
Asked as: Match the scientist to the experiment (Priestley: bell jar, mint, candle, mouse).
Ingenhousz
The same set-up worked only in sunlight, and an aquatic plant gave $O_{2}$ bubbles only from its green parts in bright light.
Asked as: Who showed that sunlight is essential and that only green parts release $O_{2}$ ?
Engelmann
Used a prism on \textit{Cladophora} with aerobic bacteria, which gathered in blue and red light. This was the first action spectrum.
Asked as: Name the organism or the detector (aerobic bacteria) in the first action spectrum experiment.
van Niel
$6 C O_{2} + 12 H_{2} O \to C_{6} H_{12} O_{6} + 6 H_{2} O + 6 O_{2}$
Working with purple and green bacteria: $O_{2}$ comes from $H_{2} O$ , not $C O_{2}$ . Overall equation as shown.
Asked as: What is the source of the evolved $O_{2}$ , and what do sulphur bacteria release instead ( $S$ or sulphate)?
Chromatogram colours
Chl $a$ is bright/blue green, chl $b$ yellow green, xanthophylls yellow, carotenoids yellow to yellow-orange. Accessory pigments pass energy to chl $a$ and protect it from photo-oxidation.
Asked as: Match the pigment to its colour; what is the role of accessory pigments?
Reaction centres
PS I has reaction centre P700 and PS II has P680. They are named in order of discovery, not in order of function (PS II works first).
Asked as: Wavelengths of the two reaction centres; why is PS II called "II"?
Water splitting
$2 H_{2} O \to 4 H^{+} + O_{2} + 4 e^{-}$
Water splitting is linked to PS II, on the inner (lumen) side of the thylakoid membrane.
Asked as: Which photosystem has the water-splitting complex, and where are the $H^{+}$ and $O_{2}$ released?
Cyclic photophosphorylation
Uses only PS I and makes only ATP, with no NADPH. It is likely in the stroma lamellae, which lack PS II and NADP reductase, and it also occurs when only light beyond $680 nm$ is available.
Asked as: Cyclic vs non-cyclic photophosphorylation (products, photosystems, location).
Chemiosmosis
Protons build up in the thylakoid lumen and flow out through $C F_{0}$ , the membrane channel. $C F_{1}$ faces the stroma and changes conformation to make ATP.
Asked as: Where do protons accumulate in chloroplasts vs mitochondria (lumen vs intermembrane space)?
Calvin's experiment
Calvin used $^{14} C$ . The first product is 3-PGA (3C), the $C O_{2}$ acceptor is RuBP (a 5C ketose sugar), and the enzyme is RuBisCO.
Asked as: The primary acceptor and first stable product in $C_{3}$ plants.
Calvin cycle energetics
The Calvin cycle has 3 stages: carboxylation, reduction, regeneration. Each $C O_{2}$ needs $3 ATP + 2 NADPH$ , so one glucose needs 6 turns, $18 ATP$ and $12 NADPH$ .
Asked as: ATP and NADPH needed for one glucose, or for one $C O_{2}$ .
Kranz anatomy
$C_{4}$ plants such as maize and sorghum have Kranz ("wreath") anatomy. Their large bundle sheath cells have many chloroplasts, thick walls impervious to gases and no intercellular spaces.
Asked as: Features of bundle sheath cells in $C_{4}$ leaves.
Hatch and Slack pathway
PEP (3C) is the acceptor and PEPcase fixes $C O_{2}$ in the mesophyll, which lacks RuBisCO. The first product is OAA (4C). The bundle sheath has RuBisCO but lacks PEPcase.
Asked as: Which enzyme is in which cell type, and the first product of $C_{4}$ fixation.
Photorespiration
RuBisCO binds $O_{2}$ and gives one phosphoglycerate + phosphoglycolate (2C). It makes no sugar, ATP or NADPH, releases $C O_{2}$ , and is absent in $C_{4}$ plants.
Asked as: Why do $C_{4}$ plants lack photorespiration ( $C O_{2}$ concentrated at the RuBisCO site in the bundle sheath)?
Blackman's law (1905)
The rate is set by the factor nearest its minimal value. Light saturation occurs at $10%$ of full sunlight, so light is rarely limiting except in shade.
Asked as: The light saturation percentage, or a statement of the law of limiting factors.
CO2 as limiting factor
$C O_{2}$ is the major limiting factor ( $0.03$ – $0.04%$ in air). $C_{4}$ plants saturate at about $360 μ L L^{- 1}$ , while $C_{3}$ plants saturate only beyond $450 μ L L^{- 1}$ , so tomatoes and bell pepper are grown in $C O_{2}$ -enriched greenhouses.
Asked as: Which group benefits from extra $C O_{2}$ , with the saturation values and crop examples.

Trap

C₄ plants do NOT skip the Calvin cycle. It runs in all photosynthetic plants. In C₄ plants it happens only in the bundle sheath cells, while C₃ plants run it in all their mesophyll cells.

How does NEET ask Photosynthesis in Higher Plants?

8 real previous-year questions from this chapter, as printed in the paper, each with its worked solution. Answer the first one here with no sign-in.

Q1BotanyNEET UG PYQFactors Affecting Photosynthesis

Try right here · No sign-in

With reference to factors affecting the rate of photosynthesis, which of the following statements is not correct?

Answer key (A) & worked solution

Correct answer: Option A

In C

_{3}

plants, photosynthesis is decreased at higher temperatures due to increased photorespiration. As a result, RuBisCO binds to oxygen instead of carbon dioxide. That's why C

_{3}

plants have a much lower temperature optimum as compared to C

_{4}

plants.C

_{4}

plants have a higher temperature optimum because of the presence of pyruvate phosphate dikinase enzyme, which is sensitive to lower temperatures. Hence, it shows a higher rate of photosynthesis at higher temperatures.

Q2BotanyNEET UG PYQSite of Photosynthesis

In a chloroplast, the highest number of protons are found in

AStroma

BLumen of thylakoids

CInter-membrane space

DAntennae complex

Answer key (B) & worked solution

Correct answer: Option B

The thylakoid lumen is a continuous aqueous phase, enclosed by the thylakoid membrane. It plays an important role for photophosphorylation during photosynthesis. During the light-dependent reaction, protons are pumped across the thylakoid membrane into the lumen making it acidic down to pH 4. The ATP synthase complex transports protons across the thylakoid from lumen to stroma. These protons flow down an electrochemical gradient and the energy released by that flow is trapped on the stroma side of the thylakoid membrane by ATP synthesis.

Q3BotanyNEET UG PYQBiosynthetic Pathway

Given below are two statements: Statement I : The primary CO

_{2}

acceptor in C

_{4}

plants is phosphoenolpyruvate and is found in the mesophyll cells. Statement II : Mesophyll cells of C

_{4}

plants lack RuBisCo enzyme. In the light of the above statements, choose the correct answer from the options given below:

ABoth Statement I and Statement II are correct

BBoth Statement I and Statement II are incorrect

CStatement I is correct but Statement II is incorrect

DStatement I is incorrect but Statement II is correct

Answer key (A) & worked solution

Correct answer: Option A

PEP is the 3C compound and acts as the primary CO

_{2}

acceptor in the mesophyll cells of C

_{4}

plants, leading to the formation of OAA, a C

_{4}

acid. Ribulose-1,5-bisphosphate carboxylase (RUBISCO) is an enzyme found in the mesophyll cells present within the C

_{3}

plants. In C

_{4}

plants, this enzyme is found in the bundle sheath cells.

Q4BotanyNEET UG PYQElectron Transport

In light reaction, plastoquinone facilitates the transfer of electrons from

APS-I to NADP

^{+}

BPS-I to ATP synthase

CPS-II to Cytb

_{6}

f complex

DCytb

_{6}

complex to PS-I

Answer key (C) & worked solution

Correct answer: Option C

In non-cyclic photophosphorylation, plastoquinone obtains electrons from PS-II and transfers them to cyt b

_{6}

-f complex.

Q5BotanyNEET UG PYQLight Reactions

Which of the following is not a product of the light reaction of photosynthesis?

ANADPH

BNADH

CATP

DOxygen

Answer key (B) & worked solution

Correct answer: Option B

ATP, NADPH, and oxygen are products of light reaction, while NADH is a product of the respiration process. NADPH is produced at PS-I, ATP is formed by ATPase, and oxygen is released at PS-II.

Q6BotanyNEET UG PYQElectron Transport

Which of the following combinations is required for chemiosmosis?

AMembrane, proton pump, proton gradient, NADP synthase

BProton pump, electron gradient, ATP synthase

CProton pump, electron gradient, NADP synthase

DMembrane, proton pump, proton gradient, ATP synthase

Answer key (D) & worked solution

Correct answer: Option D

Membrane, proton pump, proton gradient, ATP synthase.

Q7BotanyNEET UG PYQBiosynthetic Pathway

How many molecules of ATP and NADPH are required for every molecule of CO

_{2}

fixed in the Calvin cycle

A2 molecules of ATP and 2 molecules of NADPH

B3 molecules of ATP and 3 molecules of NADPH

C3 molecules of ATP and 2 molecules of NADPH

D2 molecules of ATP and 3 molecules of NADPH

Answer key (C) & worked solution

Correct answer: Option C

For every CO

_{2}

molecule entering the Calvin cycle, 3 molecules of ATP and 2 of NADPH are required.

Q8BotanyNEET UG PYQPhotorespiration

The oxygenation activity of RuBisCO enzyme in photorespiration leads to the formation of

A1 molecule of 6-C compound

B1 molecule of 4-C compound and 1 molecule of 2-C compound

C2 molecules of 3-C compound

D1 molecule of 3-C compound and 1 molecule of 2-C compound

Answer key (D) & worked solution

Correct answer: Option D

Photorespiration is the light-dependent process in which RuBisCO enzymes perform oxygenation instead of fixing carbon dioxide (C

_{3}

cycle) and oxidizes ribulose 1, 5-bisphosphate to produce a 3-carbon phosphoglyceric acid and a 2-carbon phosphoglycolate. Hence, the (d) option is correct.

Which topics in Photosynthesis in Higher Plants carry the most questions?

All 10 topics, by tagged PYQs, then practice questions. Counted from the bank. Updated 19 Oct 2026.

Topic	PYQs	Practice questions
Biosynthetic Pathway	14	156
Light Reactions	5	62
Photorespiration	4	39
Electron Transport	3	53
Photosynthesis: Early Experiments	2	51
Pigments Involved in Photosynthesis	2	39
Factors Affecting Photosynthesis	1	41
Introduction to Photosynthesis	1	19
Miscellaneous Examples	1	17
Site of Photosynthesis	1	6

Why does Photosynthesis in Higher Plants show "–" until you answer 3 questions?

Unknown is not zero. Until you answer at least 3 graded questions in Photosynthesis in Higher Plants, ViJEEta shows – instead of a zero or a 50% default. Book exercises can raise chapter mastery up to 0.60, adaptive practice up to 0.75, and only a timed chapter test or mock can certify 0.80 and above.

How ViJEEta scores you

What happens when you test Photosynthesis in Higher Plants?

Every chapter test is 25 questions. It starts at moderate difficulty and adapts after each saved answer. If you open a solution before answering, that attempt earns no credit, so your mastery stays honest.

Start the Photosynthesis in Higher Plants test

Chapters either side of Photosynthesis in Higher Plants by weight

Organisms and Populations Weight 4.7/100 Anatomy of Flowering Plants Weight 4.5/100 Plant Growth and Development Weight 4.0/100 Environmental Issues Weight 3.9/100

Photosynthesis in Higher Plants: NEET PYQs and weightage

Photosynthesis in Higher Plants: key facts for NEET

Priestley (1770)

Ingenhousz

Engelmann

van Niel

Chromatogram colours

Reaction centres

Water splitting

Cyclic photophosphorylation

Chemiosmosis

Calvin's experiment

Calvin cycle energetics

Kranz anatomy

Hatch and Slack pathway

Photorespiration

Blackman's law (1905)

CO2 as limiting factor

How does NEET ask Photosynthesis in Higher Plants?

Which topics in Photosynthesis in Higher Plants carry the most questions?

Why does Photosynthesis in Higher Plants show "–" until you answer 3 questions?

What happens when you test Photosynthesis in Higher Plants?

Chapters either side of Photosynthesis in Higher Plants by weight