Respiration in Plants Mock Test – Class 11 Biology

1. Two tissues show the following gas exchange.

Which interpretation is best supported?

2. Match each component with its respiratory role. A Column II entry is used once.

3. Leaf discs are placed in a sealed transparent chamber containing carbon dioxide but no external molecular oxygen. In light, oxygen concentration inside the chamber rises and mitochondrial ATP production continues. When the chamber is transferred to darkness, oxygen concentration and mitochondrial ATP production both decline. The strongest inference is:

4. Arrange the following events in the order followed by electrons after they have entered reduced ubiquinone.
P. Ubiquinol is oxidised by complex III.
Q. Cytochrome c receives electrons.
R. Complex IV accepts electrons from cytochrome c.
S. Oxygen receives electrons at the terminal stage.

5. Seven glucose molecules undergo complete glycolysis followed by either alcoholic or lactic acid fermentation. What is the total net ATP gain from the fermentative metabolism?

6. Match each respiratory component with its correct spatial relation in a eukaryotic cell. A Column II entry is used once.

7. Green and non-green sectors of a variegated leaf are enclosed together in a transparent chamber containing carbon dioxide but no external oxygen. In light, oxygen around the non-green sector remains sufficient for mitochondrial respiration. Covering only the green sector with an opaque screen causes oxygen around the non-green sector to fall. The strongest inference is:

8. Intact mitochondria fail to consume oxygen when supplied with either NADH-linked substrates or succinate. Complexes I and II can reduce ubiquinone normally. Addition of externally reduced cytochrome c restores oxygen consumption without repairing the original defect. Which component is most likely blocked?

9. Arrange the stages that connect controlled substrate oxidation with cellular work.
P. An organic substrate undergoes an enzyme-catalysed oxidation step.
Q. Part of the released energy is conserved through an energy-coupling process.
R. ATP is formed from ADP and inorganic phosphate.
S. ATP is used during an energy-requiring cellular activity.

10. Complex IV is inhibited in isolated mitochondria supplied with NADH, oxygen and ADP. Reduced cytochrome c accumulates, while oxygen consumption and ATP production decline. The observations show that complex IV normally:

11. Electron transport establishes movement of toward the intermembrane space. A membrane defect allows of these protons to return without passing through ATP synthase. Using the relation through per ATP, how many ATP molecules can be formed from the remaining proton flow?

12. The pathway whose name literally refers to sugar splitting and whose historical alternative name is the Embden-Meyerhof-Parnas pathway is:

13. Four respiratory profiles are shown below.

Which profile is biologically inconsistent?

14. A graph plots oxygen concentration inside identical green tissues against time. Under illumination, Curve P rises and reaches a plateau. In darkness, Curve Q steadily declines. External oxygen conditions are identical for both tissues. The pattern is best explained by:

15. Arrange the events that allow a stored fat to contribute carbon to respiration.
P. The fat is split into glycerol and fatty acids.
Q. Glycerol and fatty acids undergo different preparatory conversions.
R. Glycerol-derived carbon enters near PGAL, while fatty-acid-derived carbon enters as acetyl CoA.
S. Both routes become connected with the central respiratory pathway.

16. Carbohydrate and fat are oxidised simultaneously. Which symbolic relation correctly gives the overall respiratory quotient?

17. Four proposed pathway profiles are shown below.

The internally consistent profile is:

18. Four mitochondrial preparations are supplied with ADP, inorganic phosphate, electron donors and oxygen.

Substantial oxidative ATP formation is expected in:

19. Assertion: An observed RQ of always proves that protein is the only respiratory substrate.
Reason: Protein respiration is assigned an approximate RQ of .

20. Oxygen is restored after a brief, fully reversible oxygen-free interval in isolated mitochondria. The electron carriers and membrane complexes have not been damaged. The most likely response is:

21. Arrange the following events in the correct order during the ATP-investment part of glycolysis.
P. Glucose is converted into glucose-6-phosphate using ATP.
Q. Glucose-6-phosphate is rearranged into fructose-6-phosphate.
R. Fructose-6-phosphate is phosphorylated using another ATP.
S. Fructose-1,6-bisphosphate becomes available for cleavage.

22. A graph follows a facultative anaerobe before and after oxygen is introduced at time . After , the slope of ethanol accumulation decreases, oxygen consumption begins, the slope of ATP accumulation increases and glucose consumption per unit ATP falls. Which interpretation best fits the graph?

23. In a labelled-carbon experiment, fatty-acid carbon appears first in acetyl CoA and later in TCA intermediates. At the same time, carbon from one TCA intermediate is detected in newly synthesised amino acids. The combined observations demonstrate that:

24. Glycolysis is strongly inhibited in an oxygenated tissue that is mobilising stored fat. Some TCA-cycle activity continues, although glycerol-derived respiratory flow declines. The continued cycle activity is best explained by:

25. Four pathway descriptions are proposed for the respiratory use of fat.

The internally consistent profile is:

26. Arrange the following carbon events for complete aerobic oxidation of one glucose molecule.
P. One glucose forms two pyruvates.
Q. Two pyruvates form two acetyl groups and release .
R. Each acetyl group combines with oxaloacetate and enters one TCA turn.
S. The two TCA turns release a further .

27. Isolated mitochondria supplied with pyruvate and oxygen show active TCA turnover. Oxygen is then removed. NADH accumulates, declines and the TCA rate falls, although pyruvate and oxaloacetate remain available. The strongest inference is:

28. Pyruvate decarboxylase is completely inhibited in anaerobic yeast while glycolysis initially continues. The expected immediate pattern is:

29. The theoretical ATP balance for one glucose is modified in two ways: one glycolytic NADH is not oxidised through the mitochondrial system, and one of the two TCA-derived FADH molecules also fails to donate electrons. All other products retain their stated yields. What is the revised ATP total?

30. Metabolite levels are measured after a glycolytic lesion.

Which step is most likely blocked?

31. Fermentation is best described as:

32. Assess the following claims about oxygen availability and respiration.
I. Aerobic respiration depends on the availability of oxygen.
II. Facultative anaerobes can alter their respiratory mode when oxygen conditions change.
III. Obligate anaerobes grow equally well in oxygen-rich and oxygen-free environments.
IV. Anaerobic energy-releasing pathways can operate without oxygen.

33. Match each component with its role in mitochondrial electron transport. A Column II entry is used once.

34. The most accurate relationship between glycolysis and fermentation is:

35. Two tissues oxidise pure glucose and each consumes of oxygen while releasing of carbon dioxide. Tissue P produces abundant ATP with moderate heat release. Tissue Q produces much less ATP and releases more heat. Which interpretation is best supported?

36. A leaf cell receives adequate water, minerals and respiratory substrate, but its ATP production falls sharply. The pair of processes most directly affected will be:

37. A radial section of a woody stem is described from outside inward: protective bark containing scattered openings, a narrow zone of living cells, and a broad central region composed mainly of dead supportive elements. The principal respiratory-gas route is:

38. Two glucose molecules undergo complete aerobic oxidation under the theoretical -per-glucose assumptions. What combined gas and energy values are expected?

39. Match each feature of a woody stem with its most direct biological significance. A Column II entry is used once.

40. Four acetyl CoA molecules each complete one TCA turn. What combined output is obtained from the cycle?

41. Intact mitochondria are supplied with pyruvate, oxygen, ADP and inorganic phosphate. After Treatment P, oxygen consumption remains high, the proton gradient becomes very small and ATP production falls sharply. Which change most directly explains the observations?

42. The stomata of all leaves and the lenticels of all woody stems are sealed with an impermeable material, while root surfaces remain exposed to aerated soil. The earliest direct effect is expected to be:

43. During a defined interval, a cell produces equivalents from respiratory reactions but simultaneously uses equivalents for transport, synthesis and movement. What increase in the cellular ATP pool is expected during the interval, assuming no other ATP inputs or losses?

44. Assertion: Complex IV receives electrons directly from ubiquinone.
Reason: Complex IV receives electrons from cytochrome c and transfers them to oxygen.

45. One glucose molecule completes glycolysis. One of its two pyruvates is reduced to lactate, while the other undergoes complete aerobic oxidation through the link reaction, one TCA turn and oxidative phosphorylation. Use the assignments per NADH and per FADH. What total ATP yield and carbon-dioxide release are predicted?

46. Citrate synthase is selectively inhibited in mitochondrial matrix preparations supplied with abundant oxaloacetate and acetyl CoA. The earliest expected change is:

47. Consider the following statements about the organisation of glycolysis.
I. The complete pathway consists of ten enzyme-catalysed reactions.
II. One six-carbon glucose ultimately forms two three-carbon pyruvates.
III. Every reaction before hexose cleavage occurs twice per glucose.
IV. Reactions after cleavage proceed through two triose-level streams.

48. Two mitochondrial preparations show high NADH, reduced cytochrome c, low oxygen consumption and low ATP formation. Preparation P had oxygen removed; Preparation Q contains abundant oxygen but has a defective complex IV. Oxygen is restored to P, while no other treatment is applied to Q. Which result is expected?

49. Match each component with its role in supplying carbohydrate to glycolysis. A Column II entry is used once.

50. Consider the following statements about responses to changing oxygen availability.
I. A facultative anaerobe may shift from aerobic respiration to fermentation when oxygen is removed.
II. Its ATP yield per glucose generally falls after this shift.
III. An obligate anaerobe necessarily grows faster when oxygen is introduced.
IV. Fermentation products may accumulate in the oxygen-free condition.