NEET MCQs Practice on Photosynthesis in Higher Plants Class-XI Biology, Free unlimited practice on Photosynthesis in Higher Plants Class-XI Biology Mcqs

Question 31 of 100

📘 CLASS XI

Consider the following statements regarding the site and components of the water-splitting complex:

I. The water-splitting complex is associated with PS II.
II. It is physically located on the outer (stroma-facing) surface of the thylakoid membrane.
III. Water is split into protons (H+), oxygen ([O]), and electrons (e−).
IV. Photolysis occurs in the stroma lamellae where PS II is abundant.

Which of the statement(s) given above is/are correct?

Statements I and III are correct because PS II carries out photolysis of water. Statement II is incorrect because the water-splitting complex is located on the lumen side of the thylakoid membrane. Statement IV is incorrect because stroma lamellae lack PS II.

Question 32 of 100

📘 CLASS XI

Regarding the structural and functional differences between grana thylakoid membranes and stroma lamellae membranes:

I. Grana lamellae possess both PS I and PS II.
II. Stroma lamellae membranes lack PS II as well as NADP reductase enzyme.
III. Non-cyclic photophosphorylation occurs predominantly in the grana thylakoids.
IV. Cyclic photophosphorylation takes place in stroma lamellae when only light beyond 680 nm is available.

Which of the statement(s) given above is/are correct?

All four statements are correct. Grana contain both photosystems and perform non-cyclic photophosphorylation, whereas stroma lamellae lack PS II and NADP reductase, carrying out cyclic photophosphorylation under suitable conditions.

Question 33 of 100

📘 CLASS XI

Consider the following statements regarding the Chemiosmotic Hypothesis proposed by Peter Mitchell for chloroplasts:

I. Proton accumulation during light reactions occurs inside the thylakoid lumen.
II. In mitochondria, proton accumulation during electron transport occurs in the intermembrane space.
III. Chemiosmosis requires a membrane, a proton pump, a proton gradient, and ATP synthase.
IV. Protons are pumped from the lumen into the stroma to build the electrochemical gradient.

Which of the statement(s) given above is/are correct?

Statements I, II and III are correct because chloroplasts accumulate protons inside the thylakoid lumen, mitochondria accumulate them in the intermembrane space, and chemiosmosis requires a membrane, proton pump, proton gradient and ATP synthase. Statement IV is incorrect because protons are accumulated in the lumen, not pumped into the stroma to generate the gradient.

Question 34 of 100

📘 CLASS XI

With reference to the role of Plastoquinone and NADP reductase in proton gradient formation:

I. The primary electron acceptor of PS II transfers its electron to a hydrogen carrier (Plastoquinone) located towards the outer side of the membrane.
II. Plastoquinone removes a proton from the stroma when accepting an electron.
III. When Plastoquinone passes its electron to an electron carrier on the inner side, it releases the proton into the lumen.
IV. NADP reductase on the lumen side consumes protons from the lumen to reduce NADP+.

Which of the statement(s) given above is/are correct?

Statements I, II and III are correct because plastoquinone transports electrons and protons from the stroma to the lumen, contributing to the proton gradient. Statement IV is incorrect because NADP reductase is located on the stroma side and utilizes protons from the stroma.

Question 35 of 100

📘 CLASS XI

Regarding the ATP Synthase enzyme in thylakoid membranes, consider the following statements:

I. CF0 forms a transmembrane channel across the thylakoid membrane.
II. Proton movement through CF0 occurs via active transport against the concentration gradient.
III. CF1 protrudes on the outer surface of the thylakoid membrane facing the stroma.
IV. Flow of protons through CF0 causes conformational changes in CF1 leading to catalytic synthesis of ATP.

Which of the statement(s) given above is/are correct?

Statements I, III and IV are correct because CF0 is the membrane channel, CF1 projects into the stroma, and proton flow through CF0 drives ATP synthesis by conformational changes in CF1. Statement II is incorrect because proton flow is passive down the electrochemical gradient.

Question 36 of 100

📘 CLASS XI

Consider the following statements regarding radioactive isotope tracer studies in photosynthesis:

I. Melvin Calvin used radioactive 14C in algal photosynthesis studies.
II. Radioactive isotope 18O was used to prove that oxygen evolved during photosynthesis originates from water.
III. Calvin discovered that the initial fixed carbon product in C3 plants was a 4-carbon acid.
IV. Work with 14C allowed mapping of the complete dark reaction sequence, earning Calvin the Nobel Prize in 1961.

Which of the statement(s) given above is/are correct?

Statements I, II and IV are correct. Calvin used 14C-labelled carbon dioxide to map the Calvin cycle and received the Nobel Prize in 1961. 18O experiments demonstrated that oxygen released during photosynthesis originates from water. Statement III is incorrect because the first stable product is 3-phosphoglycerate (3-PGA).

Question 37 of 100

📘 CLASS XI

Regarding the primary CO2 acceptor in the Calvin cycle, evaluate the following statements:

I. Scientists initially expected a 2-carbon acceptor compound because the first product was a 3-carbon acid.
II. The primary CO2 acceptor was discovered to be Ribulose-1,5-bisphosphate (RuBP).
III. RuBP is a 5-carbon aldose sugar.
IV. One molecule of RuBP combines with one molecule of CO2 to yield two molecules of 3-PGA.

Which of the statement(s) given above is/are correct?

Statements I, II and IV are correct. RuBP is the primary CO2 acceptor and combines with CO2 to produce two molecules of 3-PGA. Statement III is incorrect because RuBP is a 5-carbon ketose sugar, not an aldose.

Question 38 of 100

📘 CLASS XI

Consider the following statements regarding the Carboxylation step of the Calvin Cycle:

I. Carboxylation is the most crucial step of the Calvin cycle.
II. CO2 is utilized for the carboxylation of RuBP to form two molecules of 3-PGA.
III. The reaction is catalysed by the enzyme RuBP carboxylase-oxygenase (RuBisCO).
IV. Carboxylation requires the direct consumption of 2 ATP and 2 NADPH per CO2 fixed.

Which of the statement(s) given above is/are correct?

Statements I, II and III are correct because RuBisCO catalyses fixation of CO2 into RuBP to form two molecules of 3-PGA. Statement IV is incorrect because ATP and NADPH are consumed during reduction and regeneration, not during carboxylation.

Question 39 of 100

📘 CLASS XI

Regarding the Reduction stage of the Calvin cycle, consider the statements below:

I. Reduction involves a series of reactions leading to triose phosphate and sugar synthesis.
II. Per CO2 fixed, 2 molecules of ATP are used for phosphorylation and 2 molecules of NADPH for reduction.
III. To produce one molecule of glucose, 6 turns of the Calvin cycle are required.
IV. A total of 12 ATP and 12 NADPH are consumed exclusively in the reduction stage to manufacture one glucose molecule.

Which of the statement(s) given above is/are correct?

All four statements are correct. Each CO2 fixed requires 2 ATP and 2 NADPH during reduction. Six turns of the Calvin cycle are required for one glucose, consuming 12 ATP and 12 NADPH in the reduction stage.

Question 40 of 100

📘 CLASS XI

Consider the following statements regarding the Regeneration step of the Calvin Cycle:

I. Regeneration of the CO2 acceptor RuBP is essential for the cycle to continue uninterrupted.
II. The regeneration steps require 1 ATP molecule for phosphorylation per CO2 molecule entering the cycle.
III. Regeneration involves the consumption of 1 NADPH per turn.
IV. For 6 turns of the cycle, 6 ATP molecules are consumed during regeneration.

Which of the statement(s) given above is/are correct?

Statements I, II and IV are correct because regeneration of RuBP requires one ATP per CO2 fixed, amounting to six ATP for six turns. Statement III is incorrect because regeneration does not consume NADPH.

Photosynthesis in Higher Plants MCQs