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Photosynthesis in Higher Plants — NEET MCQs with answers
Chapter 11 covers the process of photosynthesis in higher plants, from early experimental discoveries to the molecular mechanisms of the light reactions (PS I, PS II, photophosphorylation) and the Calvin cycle (dark reactions), culminating in an analysis of the environmental factors that limit photosynthetic rate. It establishes that photosynthesis occurs in two distinct but coupled stages: the light-dependent reactions in thylakoid membranes and the light-independent (Calvin) cycle in the stroma.
Topics in this chapter
- 11.1 What Do We Know?
- 11.2 Early Experiments
- 11.3 Where Does Photosynthesis Take Place?
- 11.4 How Many Types of Pigments Are Involved in Photosynthesis?
- 11.5 What is Light Reaction?
- 11.6 The Electron Transport
- 11.7 Where are the ATP and NADPH Used?
- 11.8 The C4 Pathway
- 11.9 Photorespiration
- 11.10 Factors Affecting Photosynthesis
Free practice questions
Photorespiration begins with the reaction of O2 with:
- A. 3PGA
- B. PEP
- C. OAA
- D. RuBP
Show answer
Answer: D — In photorespiration, RuBP (the same substrate of the carboxylation step) binds with O2 instead of CO2.
NCERT Class 11 Biology Ch 11.9
For every molecule of CO2 entering the Calvin cycle, the total requirement is
- A. 2 ATP and 2 NADPH
- B. 2 ATP and 3 NADPH
- C. 3 ATP and 3 NADPH
- D. 3 ATP and 2 NADPH
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Answer: D — NCERT: 'Hence for every CO2 molecule entering the Calvin cycle, 3 molecules of ATP and 2 of NADPH are required.' That is 2 ATP + 2 NADPH in reduction plus 1 ATP in regeneration.
NCERT Class 11 Biology Ch 11.7
A graph plotting the rate of photosynthesis against wavelength of light is called the:
- A. Emission spectrum
- B. Absorption spectrum
- C. Visible spectrum
- D. Action spectrum
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Answer: D — NCERT Figure 11.3b shows the wavelengths at which maximum photosynthesis occurs and is labelled the action spectrum of photosynthesis; the absorption spectrum instead plots light absorbed by a pigment.
NCERT Class 11 Biology Ch 11.4
Which of the following correctly describes the site of OAA formation in C4 plants?
- A. Mesophyll cells
- B. Bundle sheath cells
- C. Epidermis
- D. Vascular tissue
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Answer: A — NCERT states that the C4 acid OAA is formed in the mesophyll cells, where PEPcase carboxylates PEP.
NCERT Class 11 Biology Ch 11.8
By placing a Priestley-like set-up once in the dark and once in the sunlight, Jan Ingenhousz demonstrated that:
- A. Carbon dioxide is the source of evolved oxygen
- B. Chlorophyll is located in special bodies
- C. Glucose is stored as starch
- D. Sunlight is essential for the plant process that purifies fouled air
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Answer: D — NCERT: Ingenhousz 'showed that sunlight is essential for the plant process that somehow purifies the air fouled by burning candles or breathing animals.'
NCERT Class 11 Biology Ch 11.2
Which factor is described by NCERT as the MAJOR limiting factor for photosynthesis?
- A. Carbon dioxide concentration
- B. Water
- C. Temperature
- D. Light intensity
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Answer: A — NCERT opens section 11.10.2 with the statement that carbon dioxide is the major limiting factor for photosynthesis, its atmospheric concentration being very low (0.03–0.04 per cent).
NCERT Class 11 Biology Ch 11.10
Chlorophyll is described in NCERT section 11.1 as:
- A. A colourless enzyme of the leaf
- B. The red pigment of the leaf
- C. The yellow pigment of the leaf
- D. The green pigment of the leaf
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Answer: D — NCERT 11.1 refers to 'chlorophyll (green pigment of the leaf)'.
NCERT Class 11 Biology Ch 11.1
The immediate carbohydrate product of the enzymatic reactions of the stroma, before starch is formed, is:
- A. cellulose
- B. sugar
- C. starch
- D. pectin
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Answer: B — NCERT states that in the stroma enzymatic reactions synthesise sugar, which in turn forms starch — sugar is therefore the earlier product.
NCERT Class 11 Biology Ch 11.3
Which combination correctly lists ALL four events of the light reaction as given in NCERT?
- A. Light absorption, water splitting, oxygen release, ATP and NADPH formation
- B. Light absorption, photorespiration, ATP hydrolysis, oxygen uptake
- C. Light absorption, CO2 fixation, sugar formation, oxygen release
- D. Water splitting, CO2 fixation, NADPH oxidation, starch synthesis
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Answer: A — NCERT: light reactions include light absorption, water splitting, oxygen release, and formation of the high-energy chemical intermediates ATP and NADPH.
NCERT Class 11 Biology Ch 11.5
If a chloroplast is illuminated only with light of wavelength 720 nm, which of the following will NOT be produced?
- A. ATP
- B. NADPH + H+
- C. Excited P700
- D. Proton gradient
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Answer: B — Light beyond 680 nm drives only cyclic photophosphorylation (PS I alone). NCERT states cyclic flow gives only ATP, not NADPH + H+; without PS II there is also no water splitting and no O2. ATP will still be made.
NCERT Class 11 Biology Ch 11.6
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