Class XI · Biology practice
Photosynthesis in Higher Plants PYQs Check your understanding, bookmark questions and revisit your mistakes.
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23 questions in this collection · Page 2 of 3
Photosynthesis In Higher Plants
Which of the following statements is incorrect?
A RuBisCO is a bifunctional enzyme B In C4 plants, the site of RuBisCO activity is mesophyll cell C The substrate molecule for RuBisCO activity is a 5-carbon compound D RuBisCO action requires ATP and NADPH
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Explanation: Option 2 is incorrect because in C4 plants, RuBisCO is active mainly in bundle sheath cells, not in mesophyll cells. In C4 photosynthesis, CO2 is initially fixed in mesophyll cells into a 4‑carbon compound, which is then released to bundle sheath cells where RuBisCO fixes CO2 in the Calvin cycle.
🧠 Did You Know? RuBisCO is a bifunctional enzyme—it can act as both a carboxylase and an oxygenase, catalyzing CO2 fixation as well as O2 reaction with RuBP.
💡 NCERT Memory Line: RuBisCO fixes CO2 in the Calvin cycle; ATP and NADPH are used in regenerating RuBP, not in the direct carboxylation step by RuBisCO.
Photosynthesis In Higher Plants
During non-cyclic photophosphorylation, when electrons are lost from the reaction centre at PS II, what is the source which replaces these electrons?
A Oxygen B Water C Carbon dioxide D Light
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Photosynthesis In Higher Plants
Which of the following are required for the dark
reaction of photosynthesis?2
A D and E only B A, B and C only C C, D and E only D B, C and D only
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Photosynthesis In Higher Plants
How many molecules of ATP and NADPH are required for every molecule of CO? fixed in the Calvin cycle?
A 2 molecules of ATP and 2 molecules of NADPH B 2 molecules of ATP and 3 molecules of NADPH C 3 molecules of ATP and 2 molecules of NADPH D 3 molecules of ATP and 3 molecules of NADPH
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Explanation: NCERT Page. 145 (Topic: 11.7.2 The Calvin Cycle)
Photosynthesis In Higher Plants
Given below are two statements:Statement I: In C3 plants, some O2 binds to RuBisCO, hence CO2 fixation is decreased.Statement II: In C4 plants, mesophyll cells show very little photorespiration while bundle sheath cells do not show photorespiration.
A Both Statement I and Statement II are false B Both Statement I and Statement II are true C Statement I is false but Statement II is true D Statement I is true but Statement II is false
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Explanation: NCERT Page No.147, (Topic-11.9 PHOTORESPIRATION)
Photosynthesis In Higher Plants
Which pigment has absorption peak at 700 nm in the photosynthetic reaction centre PS I (P700)?
A Chlorophyll b B Chlorophyll a C Xanthophylls D Carotenoids
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The reaction centre of Photosystem I is P700, a special form of chlorophyll a that absorbs light maximally at 700 nm.
Photosynthesis In Higher Plants
Select the correct sequence of experiments that led to a gradual understanding of photosynthesis in green plants.
A Absorption spectra of chlorophyll a and b → production of glucose → release of oxygen → role of air B Role of air → release of oxygen → production of glucose → absorption spectra of chlorophyll a and b C Release of oxygen → production of glucose → absorption spectra of chlorophyll a and b → role of air D Production of glucose → role of air → release of oxygen → absorption spectra of chlorophyll a and b
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The understanding of photosynthesis progressed from proving the role of air, to oxygen evolution, carbohydrate formation and finally pigment absorption studies.
Photosynthesis In Higher Plants
How many turns of Calvin cycle are required for the formation of three molecules of glucose?
A 6 B 3 C 1 D 18
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Six turns of the Calvin cycle produce one glucose molecule. Therefore, three glucose molecules require 18 turns.
Photosynthesis In Higher Plants
Which of the following statements regarding photorespiration are correct?2 is consumed and O2 is generated
A (a) and (d) only B (c) and (d) only C (b) and (d) only D (a) and (b) only
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Photorespiration occurs in C3 plants, forms phosphoglycolate and does not produce ATP or NADPH.
Photosynthesis In Higher Plants
Photorespiration reaction catalyzed by RuBisCo is shown below:2 → 3-Phosphoglycerate + X
A Phosphoenolpyruvate B 2-Phosphoglycolate C Oxaloacetate D Malate
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During photorespiration, RuBisCo oxygenates RuBP to produce one molecule of 3-phosphoglycerate and one molecule of 2-phosphoglycolate.
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