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Photosynthesis in Higher Plants Complete NCERT Notes, Important Questions & PYQs for NEET 2026



Photosynthesis is one of the most important chapters in Class 11 Biology and carries significant weightage in NEET. Every year, multiple questions are asked directly from NCERT concepts, diagrams, and terminology. If you master this chapter, you can easily secure valuable marks in Biology.



What is Photosynthesis?

Photosynthesis is the process by which green plants prepare their own food using sunlight, carbon dioxide, and water.
Chemical Equation
6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O
Photosynthesis occurs in the chloroplasts of green plant cells.

Why is Photosynthesis Important?

Primary source of food on Earth
Releases oxygen into the atmosphere
Maintains carbon dioxide balance
Converts solar energy into chemical energy
Supports all ecosystems

Factors Necessary for Photosynthesis

External Factors
Light
Carbon dioxide
Water
Temperature
Internal Factors
Chlorophyll content
Leaf anatomy
Protoplasmic condition
Enzyme activity
Site of Photosynthesis
Photosynthesis occurs in the chloroplast.

Structure of Chloroplast

Outer membrane
Inner membrane
Stroma
Grana
Thylakoids

NCERT Point

Grana contain chlorophyll pigments and are the site of light reactions.
Photosynthetic Pigments.   

Chlorophyll a.  Primary pigment. Blue-green color. Reaction center pigment
Chlorophyll b.  Accessory pigment.  Yellow-green color
Carotenoids.    Carotenes.   Xanthophylls

NCERT Important Line



Chlorophyll a is the chief pigment involved in photosynthesis.
Light Reaction.   Occurs in the thylakoid membrane.

Major Events

Absorption of light energy
Splitting of water (Photolysis)
Oxygen release
ATP formation
NADPH formation
Photolysis of Water
2H₂O → 4H⁺ + 4e⁻ + O₂

Products

ATP
NADPH
Oxygen

Photosystems

Photosystem II (PS II).  Reaction center P680
First photosystem to function
Photosystem I (PS I).  Reaction center P700
Produces NADPH

NEET Favorite Question

Which photosystem participates first in light reaction?
Answer: Photosystem II

Electron Transport System
Electrons move through:
PS II → PQ → Cyt b6f → PC → PS I → Fd → NADP
This movement generates ATP.

Cyclic and Non-Cyclic Photophosphorylation

Feature.   Cyclic.    Non-Cyclic
Photosystem.  PS I.    PS I & PS II
ATP.      Produced.      Produced
NADPH.    Not produced.    Produced
Oxygen.    Not released.     Released

Dark Reaction (Calvin Cycle)

Occurs in the stroma.

Three Phases

Carboxylation
Reduction
Regeneration

Key Enzyme

RuBisCO
RuBisCO is the most abundant enzyme on Earth.

First Stable Product

3-Phosphoglyceric Acid (3-PGA)

C3 Plants

Examples:
Wheat
Rice
Sunflower

Characteristics

First product: 3-PGA
Calvin cycle only
Less efficient under high temperature

C4 Plants

Examples:
Maize
Sugarcane
Sorghum

Characteristics

First product: Oxaloacetic Acid (OAA)
Kranz anatomy present
Higher photosynthetic efficiency

NCERT Important Line

Kranz anatomy is a characteristic feature of C4 plants.
Photorespiration Occurs when RuBisCO acts as oxygenase.
Consequences.  Loss of fixed carbon
Energy wastage.  Reduced productivity
Absent In.  BC4 plants

C3 vs C4 Plants

Feature.    C3.     C4
First Product.   3-PGA.    OAA
Kranz Anatomy.       Present
Photorespiration.   High.   Negligible
Efficiency.    Lower.    Higher

Most Important NCERT Points
Remember These

Chlorophyll a is the chief pigment.
PS II functions before PS I.
RuBisCO is the most abundant enzyme.
ATP and NADPH are produced during light reaction.
Calvin cycle occurs in the stroma.
Kranz anatomy is present in C4 plants.
Photorespiration reduces plant productivity.

NEET PYQ-Based Questions

Q1. Which pigment acts as the reaction center in Photosystem I?
A. Chlorophyll b
B. P700
C. P680
D. Carotene
Answer: B. P700
Q2. First stable product of Calvin cycle is:
A. OAA
B. RuBP
C. PGA
D. PEP
Answer: C. PGA
Q3. Kranz anatomy is found in:
A. Wheat
B. Rice
C. Maize
D. Sunflower
Answer: C. Maize
Q4. Most abundant enzyme on Earth is:
A. DNA Polymerase
B. ATP Synthase
C. RuBisCO
D. Pepsin
Answer: C. RuBisCO

Final Revision Tips for NEET

Read every NCERT line carefully.
Memorize diagrams of chloroplast and Calvin cycle.
Practice previous year questions.
Focus on C3 vs C4 differences.
Revise photosystems and photophosphorylation repeatedly.

Conclusion

Photosynthesis in Higher Plants is one of the highest-scoring chapters in NEET Biology. Most questions are directly based on NCERT concepts, diagrams, and terminology. A strong understanding of light reaction, Calvin cycle, C3 plants, C4 plants, and photorespiration can help you secure easy marks in the exam.
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