Photosynthesis in Higher Plants — Class 11 Biology NCERT Solutions (Free)

Free step-by-step NCERT solutions for Class 11 Biology chapter "Photosynthesis in Higher Plants" — 8 important questions with detailed answers for CBSE board exam preparation.

TL;DR: Free step-by-step NCERT solutions for Class 11 Biology chapter "Photosynthesis in Higher Plants" — 8 important questions with detailed answers for CBS…

By Syllab.in · Updated Jun 14, 2026

Key Questions Covered:

What is photosynthesis?
Where do light reactions occur in the chloroplast?
What are the products of light reactions?
Explain the Calvin cycle in brief.
What is the difference between C3 and C4 photosynthesis?
What is photorespiration? Why is it considered wasteful?
+ 2 more questions in the full chapter

Solutions Summary:

Question	Status
What is photosynthesis?	✓ Solved
Where do light reactions occur in the chloroplast?	✓ Solved
What are the products of light reactions?	✓ Solved
Explain the Calvin cycle in brief.	✓ Solved
What is the difference between C3 and C4 photosynthesis?	✓ Solved
What is photorespiration? Why is it considered wasteful?	✓ Solved

Showing 6 of 8 questions

Q1: What is photosynthesis?

Photosynthesis is an anabolic process in which light energy is used to synthesize organic compounds from carbon dioxide and water. It occurs primarily in chloroplasts of green plants and can be summarized as: CO2 + H2O + light energy → (CH2O) + O2 The process has two stages: light-dependent reactions (light reactions) and light-independent reactions (dark reactions or Calvin cycle).

Q2: Where do light reactions occur in the chloroplast?

Light reactions occur in the thylakoid membrane of the chloroplast. The thylakoids are flattened sac-like structures stacked to form grana. Photosystem II and Photosystem I are embedded in the thylakoid membrane, along with electron transport chains and ATP synthase that participate in capturing light energy and producing ATP and NADPH.

Q3: What are the products of light reactions?

The light reactions produce three main products: 1. ATP (adenosine triphosphate) - energy currency 2. NADPH (reduced form of NADP+) - reducing agent/electron donor 3. Oxygen (O2) - released as a byproduct from photolysis of water Both ATP and NADPH are used in the Calvin cycle (dark reactions) to synthesize glucose.

Q4: Explain the Calvin cycle in brief.

The Calvin cycle is a light-independent reaction occurring in the stroma. It has three stages: 1. Carbon fixation: CO2 combines with RuBP (5-carbon sugar) via enzyme RuBisCO to form 3-PGA (3-carbon compound) 2. Reduction: 3-PGA is reduced to G3P using ATP and NADPH from light reactions 3. Regeneration: G3P molecules regenerate RuBP using ATP For every 6 molecules of CO2 fixed, one glucose molecule is synthesized.

Q5: What is the difference between C3 and C4 photosynthesis?

C3 photosynthesis (Calvin pathway): CO2 directly combines with RuBP to form 3-carbon compound (3-PGA). Found in most plants (rice, wheat, peas). C4 photosynthesis: CO2 first combines with PEP (3-carbon) to form oxaloacetate (4-carbon), then converted to malate. Found in tropical plants (maize, sugarcane). C4 is more efficient in hot, dry conditions as it reduces photorespiration.

Q6: What is photorespiration? Why is it considered wasteful?

Photorespiration is the oxidation of RuBP when O2 concentration is high and CO2 is low. It occurs in C3 plants and results in the release of CO2 and consumption of ATP/NADPH without producing glucose. It is wasteful because: - No glucose is synthesized - Organic compounds are oxidized - Energy (ATP/NADPH) is consumed C4 and CAM plants minimize photorespiration by maintaining high CO2 concentrations around RuBisCO.

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