Biochemistry – Zoology Optional PYQs (2004–2026)

Here are all 90 Biochemistry questions asked in UPSC Zoology Optional Paper II from 2004 to 2026, arranged under the 6 topics of the official syllabus. Within each topic the latest questions come first.

Each question ends with a code such as [2024/15m/3b] – the year, the marks, the word limit (where UPSC set one) and the question number in the paper.

5.1] Biomolecules and bioenergetics

14 questions

1. Explain various levels of protein organization with suitable examples. [2026/20m/6a]

2. Structure of dipeptide unit of a protein. [2025/10m/150w/5d]

3. Draw structure of cholesterol and explain its role in health and diseases. [2025/15m/8b]

4. Classify carbohydrates by giving suitable examples. Also, mention characteristics of each category. [2023/20m/6a]

5. Fatty acids regulate the nature of lipids, justify. [2021/10m/150w/5a]

6. What is bioenergetics? Discuss the role of second law of thermodynamics in energy transduction. [2021/15m/6c]

7. Secondary structure of proteins. [2019/10m/5b]

8. Give the structural formula of an amino acid and show how a peptide bond formation occurs. Also explain how amino acids differ from each other. [2016/10m/5b]

9. Differentiate between saturated and unsaturated fatty acids and their functions. [2015/10m/5d]

10. Which eukaryotes do not contain repetitive DNA? Give a brief account of biological macromolecules found in all living organisms. [2013/15m/3c]

11. Interactions that stabilize the secondary and tertiary structure of proteins. [2010/15m/150w/5c]

12. Classify L-amino acids on their structural basis. What is the biochemical importance of sulphur containing amino acids? [2010/20m/6b]

13. Structure of fatty acids and lipids. [2009/20m/200w/8a]

14. Ketone bodies. [2006/20m/5a]

5.2] Metabolism and ATP

24 questions

1. Write down the reactions that produce NADH during Krebs cycle. [2025/10m/6a(i)]

2. Explain the role of proton gradient in oxidative ATP synthesis. [2025/10m/6a(ii)]

3. Discuss the role of oxidative phosphorylation in cellular and tissue metabolism. [2024/15m/8b]

4. Describe the balance sheet of ATP production in glycolysis. [2023/10m/150w/5b]

5. Draw the molecular structure of ATP synthase and diagrammatically explain the chemiosmotic concept of ATP synthesis. [2022/20m/6a]

6. Cyclic AMP is a second messenger, justify. Discuss the importance of cyclic AMP in intracellular signal transduction with suitable example. [2021/15m/6b]

7. Define oxidative phosphorylation. Describe the theories of mechanism of ATP synthesis. [2020/20m/6a]

8. “Glycolysis is considered as metabolic hub.” Justify. [2020/15m/7b]

9. Make a diagrammatic presentation of Krebs’ cycle. [2019/15m/7c]

10. Describe in detail about the respiratory chain or electron transport during oxidative phosphorylation in Mitochondria. [2018/20m/7a]

11. Give the structure of cyclic AMP and discuss its role as a second messenger by giving suitable examples. [2017/15m/7c]

12. Illustrate the organisation of electron transport particles on the inner mitochondrial membrane and explain their role in ATP synthesis. [2017/20m/8a]

13. Discuss that TCA cycle is the central pathway in the energy metabolism of a cell. [2016/20m/6b]

14. Describe with suitable diagrams the role of G-protein in the synthesis of C-AMP. Demonstrate how C-AMP activate protein kinase. [2015/10m/5a]

15. Illustrate and narrate structure of $F_1-F_0$ particles of mitochondria. How do they facilitate movement of protons across the mitochondrial membrane leading to ATP generation? [2014/10m/1b]

16. What is cyclic AMP? How is it derived? Mention the role of cyclic AMP in eukaryotic cells. [2013/10m/5b]

17. Discuss the role of various oxidoreductases in metabolism of glucose (aerobically/anaerobically) to differentially release ATP molecules. [2011/15m/1a]

18. Draw a labelled flow chart of β-oxidation of fats to display the types of enzymes that catalyze the formation of intermediates and step-wise release of ATP. [2011/20m/7a]

19. Cyclic-AMP as a second messenger. [2010/15m/150w/5a]

20. What are high energy compounds? Substantiate their role in biological systems. [2010/20m/6a]

21. Describe briefly Mitchell’s chemi-osmotic hypothesis for ATP synthesis. [2010/20m/7a]

22. Give an account of structure and role of cyclic AMP. [2009/30m/6a]

23. Explain the biochemical mechanism of conservation and release of energy in a cell. [2009/30m/6b]

24. Structure and function of cyclic AMP. [2007/20m/5a]

5.3] Hormones

19 questions

1. Biosynthesis of peptide hormones. [2026/10m/150w/5c]

2. Describe the role of pancreas in blood sugar regulation. [2026/15m/8b]

3. Classify hormones and write down the process of steroid hormone biosynthesis. [2024/15m/6b]

4. Explain the cellular mechanism of action of steroid hormones. [2022/15m/6c]

5. What are peptide hormones? With the help of schematic diagram, discuss the epinephrine cascade for the glucose release from hepatocytes. [2021/20m/6a]

6. Give a brief account of tropic hormones which affect the endocrine glands. [2019/20m/7a]

7. Describe the role of Calcitonin, Parathormone and Vitamin $D_3$ in calcium metabolism. [2018/20m/8a]

8. Explain in brief about the synthesis and functions of steroid and peptide hormones. [2016/15m/6a]

9. Define hormones. Distinguish between Steroid and Peptide hormones. Give the name of the hormones and its mechanism of action that uses $C{a}^{+2}$ and/or Calcitonin as second messenger. [2015/15m/6c]

10. Name the enzymes and hormones released by liver and pancreas. Discuss their functions in digestion of food and maintenance of blood glucose balance. [2014/10m/5b]

11. Describe the short-term and long-term effects of stress on human body. [2013/10m/5d]

12. Describe the mechanism of synthesis of protein and steroid hormones. How do they affect cellular activity? [2013/15m/6a]

13. Mention the hypothalamic-adenohypophysial secretions that stimulate, sustain and regulate adrenal cortex functions. Add a note on feedback systems. [2013/15m/7a]

14. Compare the action of steroidal and peptide hormones at organismal and cellular levels. [2012/20m/2c]

15. Mention the principal steps in the biosynthesis of insulin in β-cells of the islets of Langerhans. Add a note on the reasons for hypoglycemia and hyperglycemia, and their effects on body functions. [2011/20m/4a]

16. Compare the functions of prostaglandins and histamine. Give reasons for their being considered as hormones. [2011/20m/6c]

17. Give a schematic representation of thyroxin biosynthesis. [2010/20m/6c]

18. Biosynthesis of steroid hormones and their functions. [2009/20m/5a]

19. Mechanism of Hormone action. [2007/20m/5b]

5.4] Enzymes

8 questions

1. Activation energy based mechanism of enzyme action. [2025/10m/150w/5c]

2. Explain competitive and non-competitive enzyme inhibition. [2023/10m/150w/5e]

3. Explain enzymes, their characteristics as well as induced-fit model of mechanism of enzyme action. [2023/20m/8a]

4. Illustrate the following: (i) $A=T$ and $G\equiv C$ base pairing as a part of DNA double strand (ii) Michaelis-Menten kinetic pattern of an enzymatic reaction. [2022/15m/6b]

5. Define and explain the ‘Michaelis-Menten equation’, and write its significance in enzyme kinetics. [2019/20m/6a]

6. What is an active site? How does enzyme catalysis take place in an active site? Explain with suitable examples. [2015/15m/7c]

7. Enzymes. [2005/20m/5b]

8. What is an enzyme? Give a detailed account of the structure and functions of enzymes. [2004/60m/6]

5.5] Vitamins and co-enzymes

11 questions

1. Define vitamins. How are vitamins different from co-enzymes in their structure and functions? [2026/15m/8c]

2. Why are vitamins also called coenzymes? Justify. [2024/15m/7b]

3. Explain the source(s) and functions of the following: (i) Vitamin $B_1$ (ii) Vitamin $B_2$ (iii) Vitamin $B_{12}$ [2023/15m/7b]

4. Define coenzyme. Explain the role of coenzymes in the regulation of metabolic reactions by giving suitable examples. [2021/10m/150w/5b]

5. What are vitamins? Describe the types and biological roles of fat-soluble vitamins. [2020/15m/8b]

6. What are ‘Co-enzymes’? Explain their importance in metabolism. [2017/10m/5a]

7. Explain the functions of coenzymes with suitable examples. [2016/15m/7a]

8. What are vitamins and co-enzymes? Describe fat soluble vitamins with examples. [2015/10m/5b]

9. What are vitamins? Name and give the functions of water soluble vitamins. Tabulate the diseases that occur in humans due to hypo and hypervitaminosis. [2014/10m/5e]

10. What is anti-vitamin? Classify and describe the function of vitamins in human nutrition. [2013/15m/8c]

11. Describe the structure & physiology of fat soluble vitamins. [2006/60m/6]

5.6] Immunoglobulins and immunity

14 questions

1. Describe the mechanism of generation, differentiation and activation of T-cells. [2026/15m/7b]

2. Discuss the mechanism of action of cytotoxic-T cell. [2025/15m/7b]

3. Functions of immunoglobulins. [2024/10m/150w/5a]

4. Define immunity. Explain cell-mediated immune response in vertebrates with suitable diagram. [2022/10m/150w/5a]

5. Describe the basic structure and functions of immunoglobulins. [2020/10m/5a]

6. Explain the structure and functions of IgG immunoglobulin. [2019/15m/6b]

7. Discuss antibodies as key players of humoural immunity. [2017/15m/7b]

8. Give the classification of immunoglobulins and state their functions. Draw a labelled diagram of IgM. [2016/15m/8b]

9. Differentiate between Innate and Adaptive immunity. Justify your answer with suitable examples. [2015/10m/5e]

10. What are immunoglobulins? Describe the structure of IgG and add a note on its diversity. [2014/20m/7b]

11. How does the structure of antibody give its specificity of functions? Add a note on the causes of allergic reaction. [2012/15m/1a]

12. Role of immunoglobulins in immunity. [2009/20m/200w/8c]

13. Discuss active and passive immunity. Mention autoimmune disorders. [2007/60m/6]

14. Give short descriptions of any three of the following: Immunoglobulins. [2004/20m/5a]

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Last updated: 31 October 2026