Respiration in Plants Mock Test – Class 11 Biology

1. A mitochondrial preparation supplied continuously with acetyl CoA shows the following changes: citrate rises markedly, isocitrate remains very low, alpha-ketoglutarate and succinyl CoA decline, and carbon-dioxide production falls. Which reaction is most likely impaired?

2. Assertion: Complex III oxidises ubiquinol during mitochondrial electron transport.
Reason: Cytochrome c is a mobile carrier that transfers electrons from complex III to complex IV.

3. 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?

4. The carbon-number pattern for the decarboxylating part of one TCA turn is best represented by:

5. A plant tissue depleted of readily available carbohydrate continues consuming oxygen and producing ATP when supplied with an organic acid. Fat and protein mobilisation are experimentally prevented. This result classifies the organic acid as:

6. During intense muscular activity, oxygen supply becomes inadequate and lactate dehydrogenase is experimentally inhibited. The most likely immediate metabolic effect is:

7. Both ATP-consuming hexose-phosphorylation reactions of glycolysis are disabled in a cell-free extract. The downstream triose-level enzymes remain active. Glucose or a compound already converted from glycerol into PGAL is supplied separately. Which outcome is expected?

8. Use the mitochondrial arrangement described below. Region P is the soluble compartment enclosed by the inner membrane. Region Q is the extensively folded inner membrane itself. The correct assignment of major aerobic processes is:

9. Both pyruvates produced from one labelled glucose are formed normally. One is withdrawn intact for amino-acid synthesis, while the other undergoes complete aerobic oxidation. Which pattern is most consistent with this condition?

10. Malate is added to two mitochondrial matrix preparations containing adequate . Preparation P contains active malate-oxidising enzyme; Preparation Q contains an inhibitor of that enzyme. P forms oxaloacetate and , whereas Q does not. The result shows that:

11. Four metabolic profiles are compared.

The profile that most completely represents an amphibolic respiratory network is:

12. 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.

13. A graph plots RQ against time in a germinating seed. The curve begins near , then gradually falls and stabilises near . Which change is most consistent with this trend?

14. Arrange the four-carbon intermediates in the order leading back to oxaloacetate.
P. Succinate
Q. Fumarate
R. Malate
S. Oxaloacetate

15. A tissue completely oxidises carbohydrate and consumes of oxygen. Assuming the expected carbohydrate RQ, what volume of carbon dioxide is released?

16. The following values apply to complete mitochondrial processing of the two pyruvates produced from one glucose.

The combined matrix output is:

17. 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?

18. Arrange the events linking cytoplasmic glycolysis to entry of carbon into the TCA cycle.
P. Glycolysis forms pyruvate.
Q. Pyruvate enters the mitochondrial matrix.
R. Pyruvate undergoes oxidative decarboxylation.
S. Acetyl CoA becomes available to combine with oxaloacetate.

19. 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?

20. Consider the following statements about entry of acetyl CoA into the TCA cycle.
I. Citrate synthase catalyses condensation of the acetyl group with oxaloacetate.
II. A acetyl group combines with oxaloacetate to form citrate.
III. Coenzyme A remains permanently incorporated into citrate.
IV. Water participates while coenzyme A is released.

21. Arrange the events of lactic acid fermentation in their correct order.
P. Glycolysis produces pyruvate and .
Q. Pyruvate accepts reducing equivalents.
R. Lactic acid is formed.
S. becomes available again for glycolysis.

22. Carbon flow from pyruvate is compared in two anaerobic pathways.

The most accurate inference is:

23. Consider the following statements about pyruvate as a metabolic branch point.
I. Glycolysis produces pyruvate before the aerobic and fermentative routes diverge.
II. Oxygen availability and organismal type influence the later fate of pyruvate.
III. Every fate of pyruvate releases carbon dioxide.
IV. Under aerobic conditions in eukaryotic cells, pyruvate can enter the mitochondrion.

24. A mitochondrial defect prevents ubiquinone from accepting electrons, while complexes I and II can still interact with their respective donors. The expected consequence is:

25. Respiratory quotient is calculated as the ratio of:

26. Anaerobic yeast is treated with an inhibitor of alcohol dehydrogenase. Acetaldehyde and accumulate, while ethanol and formation decline. The observations indicate that alcohol dehydrogenase normally:

27. A living tissue has a stable RQ of . No information is available about whether it is oxidising one substrate or a mixture. The most defensible conclusion is:

28. Two treatments are applied separately to inner-mitochondrial-membrane preparations.
Treatment P removes a small mobile protein from the membrane surface and interrupts transfer from complex III to complex IV.
Treatment Q removes a lipid-soluble mobile carrier and interrupts transfer from both complexes I and II to complex III.
The removed carriers in P and Q are, respectively:

29. Using the tripalmitin relation , the closest respiratory-quotient value is:

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

31. 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.

32. Match each carbohydrate-related component with its most appropriate role. A Column II entry is used once.

33. Four glucose molecules are metabolised in the same cell population. Two undergo complete aerobic respiration, one undergoes alcoholic fermentation and one undergoes lactic acid fermentation. If total carbon dioxide evolved is divided by total oxygen consumed, the resulting value is greater than one. Why should this value not be interpreted as the RQ of a pure aerobic respiratory substrate?

34. GTP formed during the TCA cycle is biologically relevant mainly because it can:

35. 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:

36. Match each blocked respiratory event with the ATP-forming consequence that follows most directly. A Column II entry is used once.

37. 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.

38. One deaminated amino-acid carbon skeleton enters the TCA pathway as alpha-ketoglutarate, while two others enter separately as malate. Each proceeds until oxaloacetate is regenerated. Using per NADH and per FADH, which combined record is correct?

39. A terminal membrane complex receives electrons from cytochrome c. At that site, the net terminal relation is represented by . This relation identifies:

40. Consider the following statements about gaseous exchange in plants.
I. Plants do not possess animal-like specialised respiratory organs.
II. Local diffusion can satisfy much of the gas requirement of individual plant parts.
III. Respiratory gases are routinely transported over long distances through vascular tissues.
IV. Relatively low respiratory demand helps make local gas exchange adequate.

41. Assertion: Organic food respired by non-green root cells ultimately originates from photosynthesis.
Reason: Root cells manufacture all their respiratory carbohydrates directly from inorganic carbon in darkness.

42. The channel is selectively blocked while respiratory electron transfer initially continues. The earliest major consequence is:

43. Six pyruvate molecules undergo complete oxidative decarboxylation. The resulting products are:

44. Evaluate the following statements about glycolysis under anaerobic conditions.
I. Glycolysis does not directly use oxygen as a reactant.
II. Many anaerobic organisms depend on glycolysis for their direct ATP gain from glucose.
III. Glycolysis completely oxidises glucose into carbon dioxide and water.
IV. Fermentation can support continued glycolysis by restoring oxidised coenzyme.

45. A variegated plant has green leaves, a non-green stem region and actively growing roots. The roots continue to respire in darkness. The most direct source of their respiratory organic substrate is:

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

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

48. An enzyme required for conversion of PEP into pyruvate is inhibited while all earlier glycolytic reactions remain functional. The expected pattern is:

49. 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.

50. 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.