Respiration in Plants Mock Test – Class 11 Biology

1. Four metabolic profiles are evaluated for eligibility for the theoretical balance.

The profile that satisfies all required idealised conditions is:

2. A cell is separated into cytoplasmic, mitochondrial-matrix and inner-membrane fractions. The cytoplasmic fraction forms pyruvate from glucose. The matrix fraction forms acetyl CoA and carbon dioxide when supplied with pyruvate. The inner-membrane fraction oxidises reduced coenzymes and consumes oxygen when supplied with the required carriers. The strongest conclusion is:

3. Select the symbolic output relation for the two TCA turns supplied by one glucose molecule. The link reactions are excluded.

4. Respiring mitochondria are supplied with molecular oxygen labelled as , while pyruvate and all other substrates are unlabelled. Label appears rapidly in newly formed water but not initially in respiratory carbon dioxide. What does this result demonstrate?

5. A plant tissue receives protein containing labelled carbon and nitrogen. Later, labelled carbon appears in pyruvate, acetyl CoA and TCA-cycle intermediates, while much of the labelled nitrogen is found in a separately removed fraction. The strongest inference is:

6. Assertion: Fatty-acid-derived carbon can enter respiration without first passing through the glycolytic PGAL-to-pyruvate sequence.
Reason: Fatty acids are converted into acetyl CoA, which can enter the TCA cycle.

7. Cellular respiration is most accurately described as:

8. Equal numbers of NADH and FADH molecules donate electrons to intact mitochondria. More ATP is assigned to the NADH group. The most relevant pathway explanation is:

9. An actively respiring yeast culture is shifted from an oxygenated medium to an oxygen-free medium while glucose remains abundant. The most appropriate pathway-level prediction is:

10. Preparation P is a soluble extract supplied with PEP and ADP; it forms ATP without a membrane or oxygen. Preparation Q is an inner-membrane vesicle supplied with ADP and inorganic phosphate; it forms ATP only when a proton gradient is imposed. Which classification is correct?

11. A graph plots growth rate against increasing oxygen concentration for two microorganisms. Curve P shows substantial growth at zero oxygen and continues growing as oxygen becomes available. Curve Q shows growth only near zero oxygen and falls to no measurable growth as oxygen concentration rises. The best interpretation is:

12. The contributions of glycolysis and the following fermentative reactions are being completed in a pathway summary.

The correct pair of missing entries is:

13. Waterlogged roots are supplied continuously with abundant sucrose. Adding more sucrose does not raise their ATP level, whereas aerating the surrounding solution increases ATP production and lowers ethanol accumulation. Which conclusion best explains the results?

14. 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:

15. One enzyme acting in the middle of glycolysis is selectively inhibited. Its substrate accumulates, while all intermediates and products beyond that reaction decline. This result most strongly demonstrates that glycolysis:

16. Consider the following statements about aerobic respiration.
I. It permits substantially more energy capture from glucose than fermentation.
II. Complete oxidation yields carbon dioxide and water.
III. Oxygen availability is essential for the full aerobic pathway.
IV. Oxygen is directly consumed during the cytoplasmic reactions of glycolysis.

17. Assertion: Oxidative phosphorylation is the direct transfer of phosphate from phosphoenolpyruvate to ADP.
Reason: Oxidative phosphorylation uses energy from respiratory electron transfer to create proton-motive conditions that drive ATP synthesis.

18. A short segment of a woody stem has all its lenticels sealed, while lenticels on adjacent segments remain open. Oxygen falls and carbon dioxide rises mainly in living bark cells directly beneath the sealed segment; tissues several centimetres away remain nearly unchanged. Which inference is strongest?

19. Match each mitochondrial feature with its principal role. A Column II entry is used once.

20. Consider the following statements about respiratory quotient.
I. Carbon-dioxide volume forms the numerator.
II. Oxygen-consumption volume forms the denominator.
III. RQ is ordinarily interpreted for aerobic respiration.
IV. ATP production is not included directly in its calculation.

21. A graph plots light intensity on the horizontal axis and net carbon-dioxide exchange of a green leaf on the vertical axis. At one light intensity, net exchange is zero even though mitochondrial respiration continues. A respiratory quotient calculated directly from the leaf’s net carbon-dioxide and oxygen exchange at this point would be unreliable because:

22. Carbon numbers of four consecutive TCA intermediates are shown below.

If P is citrate and Q is isocitrate, the strongest conclusion is:

23. Suppose a plant evolved tissues with a respiratory demand as high as that of continuously active animal muscle, while retaining the same diffusion surfaces and internal air spaces. The most likely consequence would be:

24. Compare two carbon inputs from their stated entry points. Input P is glycerol-derived carbon already converted into PGAL. Input Q is a deaminated amino-acid carbon skeleton entering as malate. Which comparison is correct if each proceeds as far as its entry position permits?

25. A graph follows an aerobic cell through two changes. At time , oxygen is removed. NADH rises, oxygen consumption becomes zero and mitochondrial ATP production falls, while lactate begins accumulating. At time , oxygen is restored. NADH declines, lactate accumulation slows and mitochondrial ATP production recovers. The best interpretation is:

26. Isolated mitochondria receive either matrix NADH or succinate as the electron source. After complex I is selectively inactivated, NADH-supported oxygen consumption falls sharply, but succinate-supported oxygen consumption continues. The strongest inference is:

27. Arrange the events by which stored carbohydrate can support cellular respiration.
P. A storage carbohydrate is mobilised.
Q. Glucose or another usable sugar becomes available.
R. The sugar enters the glycolytic pathway.
S. Pyruvate is formed and can undergo further metabolism.

28. Three sealed respirometer chambers are maintained at the same temperature.

Which interpretation is best supported?

29. Use the arrangement described below. Component P is embedded across the inner mitochondrial membrane and forms a passage for protons. Component Q projects toward the matrix and contains catalytic sites for ATP formation. The correct identification is:

30. 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.

31. The following data apply to glycolysis of one glucose molecule.

The net ATP gain and total reduced coenzyme formation are:

32. Evaluate the following propositions about glycolysis.
I. It occurs in the cytoplasm.
II. One glucose molecule forms two molecules of pyruvic acid.
III. It completely oxidises all glucose carbon to carbon dioxide.
IV. It occurs in organisms using either aerobic or anaerobic metabolism.

33. 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:

34. Assertion: A finite standard respiratory quotient can always be calculated for alcoholic fermentation.
Reason: Alcoholic fermentation may release carbon dioxide without consuming molecular oxygen, while the standard RQ denominator is oxygen consumed.

35. During the first interval, a tissue oxidises carbohydrate and consumes of oxygen. During the second interval, it oxidises fat with and consumes of oxygen. What is the RQ for the two intervals combined?

36. During one interval, total oxygen consumption by a tissue is . Carbohydrate accounts for of this oxygen use. The remaining oxygen consumption is divided equally between protein and fat. Using RQ values of , and , respectively, what is the overall RQ?

37. An aerobic plant cell has abundant glucose and oxygen. Its demand for ATP suddenly falls, and measurements show that respiratory pathway rates decrease while the ATP concentration remains within a narrow range. The most appropriate explanation is:

38. A plant fixes labelled carbon dioxide into leaf carbohydrate. An insect eats the leaf, and a bird later eats the insect. Label is subsequently detected in carbon dioxide released by the bird. The most appropriate interpretation is:

39. Assertion: Complete aerobic oxidation of pyruvate in a eukaryotic cell occurs entirely in the cytoplasm.
Reason: Pyruvate formed by glycolysis must enter the mitochondrial matrix before oxidative decarboxylation and the TCA cycle proceed.

40. Four metabolic records are obtained from aerobic cells.

Which record most strongly indicates selective failure of pyruvate oxidation with glycolysis still functioning?

41. All lenticels of a short woody twig are sealed. After several hours, oxygen concentration and ATP-dependent solute transport decline in living bark cells, whereas the central heartwood shows no comparable metabolic change. Which explanation best accounts for the contrast?

42. An artificial membrane vesicle contains mitochondrial ATP synthase. The head faces the vesicle interior, which contains ADP and inorganic phosphate. Proton concentration is higher outside the vesicle, and the membrane is otherwise impermeable to protons. What is expected when the channel opens?

43. Four cellular records are obtained during glucose metabolism.

Which record most strongly supports simultaneous aerobic respiration and lactic acid fermentation within the cell population?

44. A glucose sample initially contains energy units. During fermentation, units are released: are trapped in ATP and are dissipated as heat. What percentages of the original energy are captured in ATP and retained in organic fermentation products, respectively?

45. A living cell lacks mitochondria but retains an intact cytoplasm, glycolytic enzymes, glucose, ADP and inorganic phosphate. Which process can still occur directly?

46. A graph plots oxaloacetate concentration against time in an isolated mitochondrial preparation receiving acetyl CoA continuously. Curve P falls briefly after each acetyl addition but returns near its starting level before the next addition. Curve Q falls after each addition and never recovers. The best interpretation is:

47. A waterlogged germinating seed has abundant stored carbohydrate but limited access to oxygen. Ethanol and carbon dioxide accumulate, the seed gains only a small amount of ATP per glucose and reserve consumption becomes rapid. Which explanation fits all observations?

48. A growing tissue sharply increases fatty-acid synthesis from acetyl CoA, while the total rate of acetyl CoA formation remains unchanged. The most likely immediate respiratory consequence is:

49. A pure-substrate preparation evolves of carbon dioxide and consumes of oxygen. Which substrate class is most consistent with the result?

50. Four treatments are applied separately to respiring cells.

Which pair directly removes oxidative phosphorylation without directly blocking a substrate-level phosphorylation enzyme?