Chapter 14: Respiration in Plants – Case-Based / Source-Based Questions with Answers
CBSE Class 11 Biology – Respiration in Plants | Case-Based / Source-Based Questions with Answers (NCERT Based)
Course & Examination Details
Course: CBSE Class 11 Biology
Unit: Unit IV – Plant Physiology
Chapter: Chapter 14 – Respiration in Plants
Prescribed Textbook: NCERT
Board: CBSE
CBSE Board Examination Context
- Case-based questions assess application, reasoning, and conceptual understanding
- Aligned with competency-based questions in CBSE examinations
- All answers are concise, NCERT-specific, and exam-oriented
Section A: Glycolysis (Case-Based Questions 1–8)
Case 1
A germinating seed releases energy even in absence of oxygen.
Q1. Which respiratory pathway is active initially in this condition?
Ans: Glycolysis is active as it does not require oxygen and occurs in the cytoplasm.
Case 2
A student observes ATP formation in cytoplasm without involvement of mitochondria.
Q2. Name the process responsible for this ATP formation.
Ans: Substrate-level phosphorylation during glycolysis is responsible.
Case 3
A cell shows accumulation of pyruvic acid after glucose breakdown.
Q3. Identify the stage of respiration completed.
Ans: Glycolysis has been completed, producing pyruvic acid.
Case 4
An experiment shows two ATP molecules consumed and four produced during glucose breakdown.
Q4. Name the pathway and state net ATP gain.
Ans: The pathway is glycolysis with a net gain of two ATP molecules.
Case 5
A metabolic pathway occurs in both aerobic and anaerobic organisms.
Q5. Identify the pathway and justify.
Ans: Glycolysis, as it does not require oxygen and is universal.
Case 6
A plant tissue survives temporary oxygen deficiency.
Q6. Which feature of glycolysis supports survival?
Ans: Glycolysis can continue without oxygen, supplying ATP.
Case 7
A compound links cytoplasmic and mitochondrial respiration.
Q7. Name the compound.
Ans: Acetyl-CoA links glycolysis and Krebs cycle.
Case 8
ATP is formed directly without ETS involvement.
Q8. Identify the process.
Ans: Substrate-level phosphorylation.
Section B: Krebs Cycle (Case-Based Questions 9–15)
Case 9
A reaction sequence releases CO₂ inside mitochondria.
Q9. Which cycle is responsible?
Ans: Krebs cycle.
Case 10
A six-carbon compound is formed after acetyl-CoA entry.
Q10. Name the compound formed.
Ans: Citric acid.
Case 11
Three NADH molecules are produced from one acetyl-CoA.
Q11. Identify the metabolic pathway.
Ans: Krebs cycle.
Case 12
A plant cell stops Krebs cycle under oxygen deficiency.
Q12. Give the reason.
Ans: NAD⁺ regeneration stops due to inactive ETS.
Case 13
A pathway provides intermediates for amino acid synthesis.
Q13. Name the pathway.
Ans: Krebs cycle.
Case 14
An experiment shows one ATP formed per cycle turn.
Q14. Name the process involved.
Ans: Substrate-level phosphorylation in Krebs cycle.
Case 15
Carbohydrate, fat, and protein metabolism converge at one pathway.
Q15. Identify the pathway.
Ans: Krebs cycle, the central metabolic pathway.
Section C: Electron Transport System (ETS) (Case-Based Questions 16–20)
Case 16
A structure on inner mitochondrial membrane produces maximum ATP.
Q16. Name the structure and process.
Ans: ATP synthase performing oxidative phosphorylation.
Case 17
Electrons from NADH pass through carriers to oxygen.
Q17. Identify the system involved.
Ans: Electron Transport System (ETS).
Case 18
ATP synthesis stops when oxygen supply is cut off.
Q18. Why does this happen?
Ans: Oxygen is the final electron acceptor in ETS.
Case 19
Proton gradient is essential for ATP formation.
Q19. Which mechanism explains this?
Ans: Chemiosmosis.
Case 20
Most ATP molecules are produced at one respiratory stage.
Q20. Name the stage.
Ans: Electron Transport System.
Section D: Fermentation & Respiratory Quotient (Case-Based Questions 21–25)
Case 21
A plant tissue produces ethanol and carbon dioxide.
Q21. Identify the process.
Ans: Alcoholic fermentation.
Case 22
Only two ATP molecules are produced per glucose molecule.
Q22. Which type of respiration is occurring?
Ans: Anaerobic respiration (fermentation).
Case 23
NAD⁺ must be regenerated for glycolysis to continue without oxygen.
Q23. Which process ensures this?
Ans: Fermentation regenerates NAD⁺.
Case 24
A respiratory substrate shows RQ value equal to 1.
Q24. Identify the substrate.
Ans: Carbohydrates.
Case 25
A plant uses fats as respiratory substrate.
Q25. What will be the RQ value trend?
Ans: RQ will be less than 1.
Best Suited For
- CBSE Class 11 Annual Examinations
- Competency-based & case-study questions
- NCERT-aligned conceptual assessment