Respiration in Plants Mock Test – Class 11 Biology

1. Equal quantities of the same organic substrate release energy units when fully oxidised in two experimental systems.

Which conclusion is most appropriate?

2. An inhibitor prevents glycerol from being converted into a glycolytic intermediate, but conversion of fatty acids into acetyl CoA remains functional. In a tissue using stored fat, the most likely result is:

3. Four metabolic records are obtained from aerobic cells.

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

4. Isolated mitochondria are supplied separately with NADH or succinate. A treatment blocks complex III but leaves complexes I and II capable of accepting electrons. Oxygen consumption falls sharply with both substrates. The strongest inference is:

5. A cell oxidises labelled glucose while simultaneously converting unlabelled fatty acids into acetyl CoA. Some respiratory carbon dioxide and reduced coenzymes arise from the unlabelled acetyl groups. Which conclusion is most accurate?

6. Two growing tissues receive the same amount of respiratory substrate.

Assuming comparable respiratory conditions, the pattern in tissue Q is best explained by:

7. Four respiratory profiles are compared.

Which profile consistently represents predominant aerobic fat respiration?

8. Anaerobic yeast cells receive glucose and initially produce both ATP and ethanol. A drug then blocks the first committed reactions of glycolysis. Pyruvate, ethanol and ATP production all decline sharply. The strongest inference is:

9. Select the correct order for the early processing of glucose in glycolysis.
P. Glucose is phosphorylated using ATP.
Q. Glucose-6-phosphate is formed.
R. Glucose-6-phosphate is isomerised.
S. Fructose-6-phosphate is produced.

10. A graph follows an intact mitochondrial preparation after electron donors are added. Curve P, representing the proton concentration difference across the inner membrane, rises first. Curve Q, representing ATP accumulation, begins rising shortly afterward. When the membrane becomes freely permeable to protons, both curves fall. The pattern indicates that:

11. Three pyruvate molecules undergo complete matrix oxidation through the link reaction and the TCA cycle. What total matrix output is obtained?

12. A mitochondrial matrix initially contains oxaloacetate, , FAD and all required enzymes. Its reduced coenzymes cannot be reoxidised after they form. The most likely long-term outcome is:

13. Match each biological context with the fermentative pathway that fits it best. A Column II entry may be reused.

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

The internally consistent profile is:

15. Following normal glycolysis of one glucose, one pyruvate is withdrawn intact for biosynthesis and the other undergoes complete aerobic oxidation. Both glycolytic NADH molecules receive the full stated oxidative yield. What total ATP and carbon-dioxide output are predicted?

16. A mitochondrial preparation oxidises NADH molecules and FADH molecules completely. Using the assignments of per NADH and per FADH, the predicted ATP yield is:

17. Labelled glucose is supplied to an aerobic eukaryotic cell. Label first appears in cytoplasmic pyruvate, then in matrix acetyl CoA and carbon dioxide. At the same time, reduced coenzymes formed in the matrix support oxygen consumption and ATP formation at the inner membrane. The complete pattern demonstrates:

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

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

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

20. A theoretical respiratory balance lists from oxidation of reduced coenzymes, from glycolysis and equivalents from the TCA cycle. The complete total is:

21. 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.

22. Equal amounts of glucose are supplied to two cell preparations. Preparation P lacks oxygen and converts pyruvate into lactate. Preparation Q has functional mitochondria and completely oxidises pyruvate. Both initially complete glycolysis. Which comparison is most accurate?

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

24. Consider the following statements about ATP-forming mechanisms in respiration.
I. Substrate-level phosphorylation involves direct phosphate transfer from a metabolic intermediate.
II. Oxidative phosphorylation depends on electron transfer, a proton gradient and ATP synthase.
III. Every substrate-level phosphorylation reaction stops immediately when oxygen is removed.
IV. Formation of GTP during conversion of succinyl CoA into succinate is substrate-level phosphorylation.

25. Consider the following statements about the energy needs of living organisms.
I. Uptake of some mineral ions by roots may require metabolic energy.
II. Formation of complex cellular molecules requires an energy supply.
III. Diffusion of every gas molecule across a membrane directly consumes ATP.
IV. Cell division and reproductive activity depend on energy-releasing metabolism.

26. A pathway map shows arrows entering from carbohydrates, glycerol, fatty acids and amino-acid carbon skeletons. Other arrows leave acetyl CoA and TCA-cycle intermediates toward fatty-acid and amino-acid synthesis. The outward arrows represent:

27. Two sealed aerobic preparations receive equal masses of different pure substrates. Preparation P gives , while Preparation Q gives . Which inference is best supported?

28. Identical mitochondria are supplied with NADH, oxygen, ADP and inorganic phosphate. Preparation P has an intact inner membrane, while Preparation Q has a disrupted inner membrane but functioning electron carriers. Both oxidise some NADH, yet substantial ATP forms only in P. The strongest inference is:

29. 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?

30. Arrange the events connecting respiratory electron transfer with ATP formation.
P. Electrons move through inner-membrane carriers toward oxygen.
Q. Released redox energy promotes proton accumulation in the intermembrane space.
R. A proton concentration difference develops across the inner membrane.
S. Protons return through , allowing to catalyse ATP formation.

31. Pyruvate dehydrogenase is inhibited in isolated mitochondria supplied with pyruvate, coenzyme A and . Which result is expected relative to an untreated control?

32. Arrange the early events followed by electrons donated by matrix NADH.
P. NADH is oxidised by complex I.
Q. Electrons are transferred from complex I to ubiquinone.
R. Ubiquinone is reduced to ubiquinol.
S. Ubiquinol carries the electrons toward complex III.

33. Gas exchange is recorded for four aerobic samples.

Which sample is most consistent with complete oxidation of carbohydrate?

34. Equal amounts of glucose undergo anaerobic metabolism in yeast and oxygen-limited muscle. Which comparison is correct?

35. Match each ATP-forming event with its phosphorylation type. A Column II entry may be reused.

36. Fermentation is best described as:

37. Arrange the events expected after oxygen is restored to cells that had been relying partly on lactic acid fermentation.
P. Oxygen again accepts electrons through complex IV.
Q. Respiratory carriers, including NADH, become more oxidised.
R. Oxidised coenzymes become available for pyruvate oxidation and TCA reactions.
S. Dependence on pyruvate reduction to lactate decreases.

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

Substantial oxidative ATP formation is expected in:

39. 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:

40. A mitochondrial ATP-synthase complex is inserted in the inner membrane with its headpiece facing the intermembrane space instead of the matrix. A normal proton gradient is present, but ADP and inorganic phosphate are available only in the matrix. Which outcome is most likely?

41. 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?

42. Two identical mitochondrial preparations contain reduced cytochrome c, active complex IV and suitable hydrogen ions. Preparation P receives oxygen, while Preparation Q is kept oxygen-free. P oxidises cytochrome c and forms water; Q shows neither change. The strongest inference is:

43. A cell has two simultaneous defects: glucose cannot pass through the early ATP-investment portion of glycolysis, and cytosolic pyruvate cannot enter the mitochondrial matrix. The TCA-cycle and electron-transport systems remain functional. Which pair of alternative substrates can still supply mitochondrial respiration downstream of both defects?

44. During one observation period, carbohydrate oxidation contributes of carbon dioxide and consumes of oxygen. Fat oxidation simultaneously contributes of carbon dioxide and consumes of oxygen. What is the overall RQ?

45. Oxygenated cells show normal glycolytic ATP formation but accumulate pyruvate and lactate. Their isolated mitochondria consume oxygen normally when supplied with succinate. Supplied pyruvate fails to produce acetyl CoA, carbon dioxide or NADH, whereas supplied acetyl CoA restores citrate formation and TCA activity. Which diagnosis best integrates the observations?

46. Carrier states are recorded after four treatments.

A block at complex IV is most consistent with:

47. Two sucrose molecules are hydrolysed completely, and every released monosaccharide completes glycolysis. What is the combined glycolytic output?

48. Assertion: Oxidative phosphorylation and photophosphorylation both use a proton gradient to support ATP synthesis.
Reason: The original energy establishing the gradient comes from respiratory redox reactions in oxidative phosphorylation and from light-driven reactions in photophosphorylation.

49. Preparation P contains acetyl CoA and active citrate synthase but lacks oxaloacetate. Preparation Q contains acetyl CoA and oxaloacetate but has inactive citrate synthase. Malate and are added to both preparations. Citrate forms only in P. Which interpretation is correct?

50. In cultured plant cells, oxygen enters normally and carbon dioxide can leave, but an intracellular enzyme defect prevents controlled oxidation of organic substrate. ATP production declines. The observation supports the conclusion that: