Consider the following statements regarding Joseph Priestley's bell jar experiment:
I. Priestley performed his bell jar experiments in 1770 to demonstrate the essential role of air in green plant growth. II. Priestley discovered oxygen gas in the year 1774. III. He observed that a burning candle placed inside a sealed bell jar soon got extinguished. IV. A mouse placed in a sealed bell jar alongside a mint plant suffocated within minutes.
Which of the statement(s) given above is/are correct?
Statements I, II and III are correct because Priestley (1770) demonstrated the role of air using bell jar experiments, discovered oxygen in 1774, and observed that a candle extinguishes in a sealed jar. Statement IV is incorrect because the mouse survived when a mint plant was present inside the bell jar.
Question 52 of 100
📘 CLASS XI
Regarding Jan Ingenhousz's experimental setup and observations, evaluate the following statements:
I. Ingenhousz used a setup similar to Priestley's to demonstrate the necessity of sunlight for plant processes. II. He showed that green parts of an aquatic plant formed small bubbles in the dark, but not in bright sunlight. III. The bubbles formed around green parts in sunlight were identified as oxygen gas. IV. Ingenhousz concluded that only the green parts of plants can release oxygen in the presence of light.
Which of the statement(s) given above is/are correct?
Statements I, III and IV are correct because Ingenhousz demonstrated that green parts of plants release oxygen only in sunlight. Statement II is incorrect because oxygen bubbles appeared in bright sunlight, not in darkness.
Question 53 of 100
📘 CLASS XI
Consider the following statements regarding the findings of Julius von Sachs (1854):
I. Julius von Sachs provided evidence that green parts of plants produce glucose during growth. II. He established that glucose is usually stored in plants in the form of starch. III. Sachs proved that chlorophyll is uniformly distributed throughout the plant cell cytoplasm. IV. He showed that green substance (chlorophyll) is located in specialized bodies (chloroplasts) inside plant cells.
Which of the statement(s) given above is/are correct?
Statements I, II and IV are correct because Sachs demonstrated glucose formation, starch storage, and localization of chlorophyll within chloroplasts. Statement III is incorrect because chlorophyll is not uniformly distributed throughout the cytoplasm.
Question 54 of 100
📘 CLASS XI
Regarding T.W. Engelmann's experiment with Cladophora, consider the statements below:
I. Engelmann used a glass prism to split light into its spectral components to illuminate a green alga (Cladophora). II. The alga was suspended in a medium containing aerobic bacteria to detect sites of oxygen evolution. III. Aerobic bacteria accumulated predominantly in the green and yellow regions of the spectrum. IV. Engelmann's work led to the description of the first action spectrum of photosynthesis.
Which of the statement(s) given above is/are correct?
Statements I, II and IV are correct because Engelmann split light using a prism, used aerobic bacteria to detect oxygen evolution, and described the first action spectrum. Statement III is incorrect because bacteria accumulated mainly in the blue and red regions.
Question 55 of 100
📘 CLASS XI
Consider the following statements regarding Cornelius van Niel's microbial studies on photosynthesis:
I. Van Niel conducted experiments using purple and green sulphur bacteria. II. He demonstrated that photosynthesis is a light-dependent reaction where hydrogen reduces carbon dioxide. III. Van Niel proved that the oxygen evolved by green plants originates from carbon dioxide. IV. In purple and green sulphur bacteria, H₂S acts as the hydrogen donor, yielding sulphur or sulphate as the oxidation product.
Which of the statement(s) given above is/are correct?
Statements I, II and IV are correct because Van Niel studied sulphur bacteria and proposed the general equation of photosynthesis. Statement III is incorrect because oxygen released by green plants originates from water, not carbon dioxide.
Question 56 of 100
📘 CLASS XI
With reference to photosynthetic leaf pigments separated by paper chromatography, evaluate these statements:
I. Chlorophyll a appears as a bright or blue-green color on the chromatogram. II. Chlorophyll b shows a yellow-green appearance. III. Xanthophylls appear distinctly yellow. IV. Carotenoids appear as brilliant red to deep purple spots.
Which of the statement(s) given above is/are correct?
Statements I, II and III are correct because chlorophyll a is blue-green, chlorophyll b is yellow-green, and xanthophylls are yellow. Statement IV is incorrect because carotenoids appear yellow to yellow-orange.
Question 57 of 100
📘 CLASS XI
Consider the following statements regarding Photosystem II (PS II) and its reaction centre:
I. The reaction centre Chlorophyll a in PS II has an absorption peak at 680 nm (P680). II. PS II is located exclusively on the stroma lamellae membranes. III. PS II is physically coupled with the water-splitting enzyme complex on the lumen side. IV. Excitation of P680 transfers electrons to a primary acceptor, which passes them downhill along a cytochrome chain.
Which of the statement(s) given above is/are correct?
Statements I, III and IV are correct because PS II contains the P680 reaction centre, is associated with the water-splitting complex on the lumen side, and transfers electrons through the cytochrome chain. Statement II is incorrect because PS II is present in grana thylakoids, not stroma lamellae.
Question 58 of 100
📘 CLASS XI
Regarding the splitting of water during the photochemical phase, consider the statements below:
I. Photolysis of water occurs on the stroma side of the thylakoid membrane. II. Two molecules of water split to form 4 protons (H⁺), one O₂ molecule, and 4 electrons. III. Electrons released during water splitting replace those lost by the reaction centre of PS II. IV. Protons produced during water splitting accumulate inside the thylakoid lumen.
Which of the statement(s) given above is/are correct?
Statements II, III and IV are correct because photolysis (2H₂O → 4H⁺ + O₂ + 4e⁻) supplies electrons to PS II and releases protons into the thylakoid lumen. Statement I is incorrect because water splitting occurs on the lumen side of the thylakoid membrane.
Question 59 of 100
📘 CLASS XI
Consider the following statements comparing Non-cyclic and Cyclic photophosphorylation:
I. Non-cyclic photophosphorylation involves both PS I and PS II operating in a series (Z-scheme). II. Cyclic photophosphorylation involves only PS I operating in a closed loop. III. Non-cyclic photophosphorylation produces both ATP and NADPH + H⁺. IV. Cyclic photophosphorylation predominates when light of wavelengths below 680 nm is supplied.
Which of the statement(s) given above is/are correct?
Statements I, II and III are correct because non-cyclic electron flow uses both PS II and PS I to generate ATP and NADPH, while cyclic flow uses only PS I. Statement IV is incorrect because cyclic photophosphorylation predominates when light beyond 680 nm is available.
Question 60 of 100
📘 CLASS XI
Regarding the structural features and biochemical activity of stroma lamellae:
I. Stroma lamellae membranes lack PS II. II. Stroma lamellae membranes lack the enzyme NADP reductase. III. Stroma lamellae perform non-cyclic photophosphorylation when illuminated with white light. IV. In stroma lamellae, excited electrons from PS I cycle back through the electron transport system to P700.
Which of the statement(s) given above is/are correct?
Statements I, II and IV are correct because stroma lamellae lack PS II and NADP reductase, resulting in cyclic electron flow back to P700. Statement III is incorrect because stroma lamellae carry out cyclic, not non-cyclic, photophosphorylation.
