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Photosynthesis in Higher Plants

NCERT Class 11 Biology Chapter 11

Photosynthesis in Higher Plants for Class 11 Biology and NEET: pigments, light reaction, photophosphorylation, Calvin cycle, C₄ pathway, photorespiration.

10 topics Updated 8 Nov 2026

For: Class 11 and NEET, unless a topic says otherwise

In the syllabus: NEET Class 11 syllabus

With your textbook

NCERT Biology (Class 11), Chapter 11 “Photosynthesis in Higher Plants”, reprint 2026-27.

Open the official NCERT chapter (PDF, 2.7 MB, ncert.nic.in)

Checked on 19 Oct 2026.

Learn in this order

  1. Requirements for photosynthesis

    Autotrophic nutrition, starch tests for chlorophyll and light, and Moll’s half-leaf test for CO.

    NCERT Section 11.1 7 min read 3 solved examples 4 practice questions

  2. Early experiments on photosynthesis

    Priestley’s bell jar, Ingenhousz, Sachs, Engelmann’s action spectrum, van Niel and why 12 HO are used.

    Class 11 only NCERT Section 11.2 14 min read 5 solved examples 6 practice questions

  3. Site of photosynthesis

    Mesophyll chloroplasts, a labelled chloroplast diagram, grana vs stroma, and light vs dark reactions.

    NCERT Section 11.3 10 min read 4 solved examples 6 practice questions

  4. Photosynthetic pigments

    Chlorophyll a vs b, carotenoids, accessory pigments, paper chromatography and absorption vs action spectra.

    NCERT Section 11.4 10 min read 5 solved examples 6 practice questions

  5. Light reaction of photosynthesis

    The photochemical phase, light harvesting complex vs reaction centre, and PS I vs PS II (P700 and P680).

    NCERT Section 11.5 8 min read 4 solved examples 6 practice questions

  6. Electron transport and photophosphorylation

    Water splitting at PS II, cyclic vs non-cyclic photophosphorylation and the chemiosmotic hypothesis, with diagrams.

    NCERT Section 11.6 13 min read 5 solved examples 6 practice questions

  7. Calvin cycle

    RuBP, RuBisCO, carboxylation, reduction and regeneration steps, and 18 ATP per glucose, with a diagram.

    NCERT Section 11.7 11 min read 5 solved examples 6 practice questions

  8. C₄ pathway (Hatch and Slack pathway)

    Kranz anatomy, PEPcase in the mesophyll, the Hatch and Slack pathway, why C plants are efficient, examples and diagrams.

    NCERT Section 11.8 13 min read 5 solved examples 6 practice questions

  9. Photorespiration

    Why RuBisCO binds O, why it is wasteful, why C plants avoid it, and the difference between C and C plants.

    NCERT Section 11.9 12 min read 4 solved examples 6 practice questions

  10. Factors affecting photosynthesis

    Blackman’s law of limiting factors, light, CO (C vs C), temperature and water, with graphs.

    NCERT Section 11.10 13 min read 6 solved examples 6 practice questions

Key formulas in this chapter

What photosynthesis needs

  • requirements: chlorophyll, light, CO (and water)
  • black-paper test: no starch without light
  • KOH test: no starch without CO

Early experiments

  • empirical: CO + HO → [CHO] + O (light)
  • van Niel: 2HA + CO → 2A + CHO + HO (light)
  • overall: 6CO + 12HO → CHO + 6HO + 6O
  • O comes from HO, not CO

Site of photosynthesis

  • thylakoid membrane system as a whole: light reactions → ATP, NADPH
  • stroma: dark (carbon) reactions → sugar → starch
  • dark reactions need ATP and NADPH, not darkness

Photosynthetic pigments

  • chief pigment: chlorophyll a
  • accessory pigments: chlorophyll b, xanthophylls, carotenoids
  • chlorophyll a absorbs most: blue and red
  • Rf = distance moved by pigment ÷ distance moved by solvent

Light reaction

  • light reaction products: ATP, NADPH, O
  • PS I reaction centre: P700 (700 nm)
  • PS II reaction centre: P680 (680 nm)
  • antenna: all pigments except one chlorophyll a

Electron transport

  • water splitting at PS II: 2HO → 4H + O + 4e
  • non-cyclic: PS II → PS I; ATP and NADPH
  • cyclic: PS I only; ATP only
  • ATP synthase: CF proton channel, CF makes ATP

Calvin cycle

  • RuBP (5C) + CO → 2 × 3-PGA (3C)
  • per CO: 3 ATP + 2 NADPH
  • per glucose: 6 CO, 6 turns, 18 ATP, 12 NADPH
  • stages: carboxylation, reduction, regeneration

C₄ pathway

  • PEP (3C) + HCO → OAA (4C) + Pi, by PEPcase, in mesophyll
  • C acid → CO + 3C molecule, in bundle sheath
  • mesophyll: PEPcase, no RuBisCO
  • bundle sheath: RuBisCO, Calvin cycle, no PEPcase

Photorespiration

  • carboxylase: RuBP + CO → 2 × 3-PGA
  • oxygenase: RuBP + O → phosphoglycerate + phosphoglycolate (2C)
  • photorespiration: no sugar, ATP or NADPH; CO released, ATP used
  • C: high CO at RuBisCO, no photorespiration

Factors affecting photosynthesis

  • rate set by the factor nearest its minimum (Blackman, 1905)
  • light saturation: 10 per cent of full sunlight (NCERT’s figure)
  • NCERT CO figures: C about 360 µL L, C beyond 450 µL L
  • 1 per cent = 10 000 µL L

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