Here are all 124 Biochemistry questions asked in UPSC Medical Science Optional Paper I from 1995 to 2026, arranged under the 4 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.
3.1] Organ function tests
31 questions
A 55-year-old male presented in surgery OPD with yellow-coloured sclera and greasy stools. On detailed examination, he was diagnosed with carcinoma of head of pancreas. Based on these clinical findings, discuss the following: (i) Serum markers of cholestasis (ii) Biochemical findings in serum, urine and stool sample in this patient (iii) Cause of greasy stools. [2026/10m/1c]
Define glomerular filtration rate (GFR). Discuss the different clearance tests used to measure glomerular filtration rate. [2026/10m/4b(i)]
Classify jaundice according to its aetiology. Make a tabular representation of the blood, urinary and stool findings observed in different types of jaundice. [2025/10m/1c]
Enumerate any five tests for the assessment of renal tubular functions. Explain the underlying principle and their interpretation. [2025/10m/2b(i)]
Define renal clearance. What key features should be present in a compound for it to be considered as a ‘gold standard’ for measurement of renal clearance? Explain why urea is not considered as a ‘gold standard’ for this. [2024/10m/4b(i)]
Discuss the serum biochemical markers of cholestasis. [2023/5m/3b(ii)]
Describe the role of iodine in the synthesis of thyroid hormones. Discuss briefly about Hashimoto’s Thyroiditis and the biochemical investigations that will be done for its diagnosis. [2023/15m/4b(i)]
Define physiological jaundice of the newborn. What are the predisposing causes and effects of this condition? [2022/10m/1c]
Explain the diagnostic role of thyroid function test (TFT) in the diagnosis of thyroid disorders. [2022/5m/4a(ii)]
A 14-year-old girl presented with low-grade fever, loss of appetite and yellow discolouration of conjunctiva. The attending physician suggested evaluation of liver functions of the patient. (i) Define and classify jaundice. (ii) Describe the laboratory tests for jaundice and their clinical interpretation. [2021/10m/1c]
A 15 year old boy from city slum presented with complaints of low grade fever, vomiting and yellowish discoloration of eyes. The liver function test was done and the report is as follows:
| Total Bilirubin | 7.5 mg/dl (0.1 – 1.2 mg/dl) |
| Direct Bilirubin | 3 mg/dl (0.1 – 0.3 mg/dl) |
| Indirect Bilirubin | 4.5 mg/dl (0.1 – 1.0 mg/dl) |
| Alanine Transaminase (ALT) | 500 (< 35 IU/L) |
| Aspartate Transaminase (AST) | 300 (< 40 IU/L) |
| Alkaline phosphatase (ALP) | 250 (40 – 130 IU/L) |
(i) Write the most likely diagnosis and justify it with the findings. (ii) Classify jaundice on the basis of aetiopathology and write their main biochemical findings. [2020/10m/1c]
A 35 year old man presented with complaints of generalised weakness, loss of appetite and yellowish discolouration of eyes. The liver function test was done and the report is as follows:
| Total bilirubin: | 10 mg/dL (0.1–1.2 mg/dL) |
| Direct bilirubin: | 9 mg/dL (< 0.3 mg/dL) |
| Alanine transaminase (ALT): | 31 IU/L (< 35 IU/L) |
| Aspartate transaminase (AST): | 33 IU/L (< 40 IU/L) |
| Alkaline phosphatase (ALP): | 800 IU/L (45–150 IU/L) |
(i) What is the most likely diagnosis and why? (ii) What will be the expected findings in urine and stool? [2019/10m/1c]
Define clearance. Explain its significance and enumerate the methods available for its determination. [2019/10m/4a(ii)]
Tabulate the findings of various biochemical tests in blood and urine of patients of pre-hepatic, hepatic and post-hepatic jaundice. [2017/10m/1e]
Enumerate the thyroid function tests. Give the biochemical findings in hyper- and hypo-thyroidism. [2016/20m/2a]
Discuss the laboratory investigations in a case of myocardial infarction. [2016/10m/5d]
Define ‘clearance’ of a substance by kidneys. Which clearance tests provide an estimate of glomerular filtration rate (GFR)? Explain which of these is the test of choice for assessment of GFR. What is eGFR? [2015/10m/150w/1e]
Discuss briefly: (i) Vitamin D resistant rickets (ii) Chromium as a trace element (iii) Role of plasma enzymes in evaluation of liver function. [2015/15m/3c]
What is obstructive jaundice? Enumerate the various biochemical tests which you would prescribe to the patient. Write their biochemical basis of changes you expect. [2014/15m/3c]
Write in brief:– (i) Reverse transcriptase–P.C.R. (ii) Significance of S. enzymes in liver diseases. [2013/10m/4c]
Nodular growth in neck is very common among population living in mountain areas. – Why? How will you investigate such cases? [2012/20m/4b]
Define Jaundice. Write briefly about formation and fate of bilirubin. Give the major differences between the three types of Jaundice. [2011/10m/1c]
What are the tests based on the intermediary metabolic functions of liver? Explain the basis of each of these tests. [2011/10m/1f]
Explain: (i) Non-standard amino acids and their biological functions. (ii) Importance of enzyme assay to assess liver function. [2010/20m/4c]
Describe in brief the functions of plasma proteins. Where are they synthesized? Give the role of serum electrophoresis in the diagnosis of various diseases with the help of diagrams. [2002/20m/4c]
With the help of a diagram depict the metabolic interlinks between chylomicron, VLDL and LDL. [2001/20m/4c]
Sequence the events contributing to the regulation of plasma cholesterol levels as a consequence of receptor mediated uptake of LDL by hepatic and extra-hepatic tissues. [2000/30m/4a]
What is ketoacidosis? How will you differentiate between metabolic acidosis and respiratory acidosis? [2000/30m/4b]
Describe, with the aid of diagram, the metabolic changes in a case of uncontrolled diabetes mellitus. Mention the various biochemical investigations for the diagnosis and follow-up of a diabetic patient. [1998/20m/200w/1e]
Define GFR, giving its normal value. Describe the forces determining GFR. Describe the determination of GFR based on renal clearance method. [1998/20m/2b]
How is hypercholesterolaemia harmful? Mention the causes for hypercholesterolaemia and enumerate various measures that are used to decrease serum cholesterol level and give their mechanism of action. [1995/20m/2b]
3.2] Protein synthesis
23 questions
Define genetic code. What are the salient features of genetic code? [2026/5m/3b(i)]
What are posttranslational modifications? Discuss in brief the post-translational modifications involving various amino acids. [2026/10m/3b(ii)]
Which antibiotics and toxins inhibit protein synthesis in prokaryotes and eukaryotes? Briefly explain the mechanism of action of each of them. [2024/10m/3b(i)]
What are ribozymes? Explain briefly the role of any one ribozyme in protein synthesis. [2024/5m/3b(ii)]
Define Genetic code and explain the Wobble Hypothesis. Discuss briefly the post-translational modifications of proteins. [2023/10m/2b(ii)]
Explain the process of initiation of protein synthesis in eukaryotes. Enumerate any four inhibitors of protein synthesis with their mechanism of action. [2022/10m/2c(i)]
Illustrate the structure of t-RNA with a suitable diagram and its role in protein synthesis. [2020/5m/4a(ii)]
Describe the structure of tRNA in detail. What is the energetics of synthesis of one peptide bond? What are the inhibitors of protein synthesis? [2018/20m/4a]
Write a note on post translational modifications of protein. [2012/12m/1e]
Outline the components of the translation apparatus in eukaryotes. [2011/20m/4b]
There is a precise molecular mechanism for initiating and terminating the synthesis of a polypeptide on ribosome. Explain in your own terms what happens if the termination has failed. [2009/20m/4b]
The protein molecular ultimately needed by a cell often differs from the polypeptide chain synthesised. How is the chain modified to impart biological activity? Describe with suitable examples. [2006/20m/1d]
Non-essential amino acid tyrosine is formed from phenylalanine. How does the conversion take place and how is tyrosine utilised for the formation of hormones? [2006/30m/4c]
A famous experiment was carried out by two scientists, Alfred Hershey and Martha Chase in 1952, which has shown that DNA is the chemical bearing the Genetics information in living cells. Briefly describe that Hershey Chase experiment. [2005/20m/1d]
In terms of biochemistry and molecular biology, discuss the characteristic features of ‘Living Organisms.’ [2005/20m/4c]
The DNA is the bearer of hereditary information was demonstrated long time back by scientists Avery Macleod and McCarty. Describe briefly how did they do it. [2004/20m/200w/1d]
As per the latest knowledge of the Biochemistry, how do you define a ‘Gene’? Discuss the changes that have taken place in this definition over the years. [2004/20m/4a]
State the salient features of human DNA. Outline the steps involved in the synthesis of eukaryotic DNA. Mention the major goals of human genome project. [2003/20m/4a]
Describe with the aid of a flow chart the metabolism of any one of the aromatic amino acids. Indicate the associated metabolic defects. How can this be diagnosed by laboratory tests? [2002/20m/4a]
Give a flow chart to depict synthesis of mRNA in eucaryote. State the post-transcriptional modifications. [2001/30m/4b]
Name the enzymes involved in DNA and RNA synthesis. Describe post-transcriptional modifications. [1999/20m/3c]
Briefly describe the salient features of eukaryotic DNA. What is “Recombinant DNA”? In your opinion, how does the recombinant DNA technology find practical application in biology and medicine? [1998/20m/3a]
Describe the process of protein synthesis. Name the inhibitors of protein synthesis along with their site of action. [1997/20m/3c]
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49 questions
Describe the role of various proteins regulating the iron absorption, transport and storage in the body. [2026/10m/2b(i)]
Explain the biochemical role of vitamin B6. Explain why the deficiency of vitamin B6 causes pellagra-like symptoms. [2026/10m/2b(ii)]
Explain the role of biotin in intermediary metabolism with suitable examples. Add a note on the mechanism of action of any biotin-antagonist with its application in medicine. [2025/10m/2b(ii)]
Describe Selenium under the headings of ‘its dietary sources’, ‘its biochemical roles’ and ‘its deficiency diseases’ with their clinical manifestations. [2025/10m/3b(i)]
Enumerate haematopoietic vitamins. Explain the biochemical basis of the deficiency manifestations of any ‘two’ of them which lead to anaemia. [2025/10m/4b(ii)]
Explain the ‘Mucosal Block Theory’ for iron absorption. Discuss briefly the complications of excess of iron deposition in the body. [2024/10m/1c]
Explain why vitamin D can be considered to be a ‘hormone’. Describe the role of vitamin D in calcium homeostasis. [2024/10m/2b(i)]
Discuss the sources and Recommended Daily Allowance (RDA) of vitamin B12. Briefly discuss the absorption of vitamin B12 in the GIT and the clinical manifestations of the disorder of absorption of vitamin B12. [2024/10m/2b(ii)]
Discuss the sources and Recommended Daily Allowance (RDA) of Folic Acid and the clinical manifestations of its deficiency in the body. Add a note on ‘Folate Trap’. [2023/10m/1c]
Describe the biochemical role of copper in the body. Discuss briefly about Wilson disease and the biochemical investigations that will help in its diagnosis. [2023/10m/2b(i)]
Describe the role of iodine in the synthesis of thyroid hormones. Discuss briefly about Hashimoto’s Thyroiditis and the biochemical investigations that will be done for its diagnosis. [2023/15m/4b(i)]
Explain briefly the biochemical role of Vitamin-K in the body. What is the biochemical basis of using Warfarin as an anticoagulant drug? [2023/5m/4b(ii)]
Explain the biochemical role of the different derivatives of vitamin A. Add a note on the causes, clinical manifestations and management of vitamin A deficiency. [2022/15m/3b]
Explain the mechanism of iron absorption in the intestine. What are the factors regulating the process? [2022/15m/4a(i)]
Write a note on different vitamers of vitamin and write their biochemical role in cellular metabolism. [2021/10m/2c(ii)]
Describe the sources, RDA and biochemical significance of vitamin C. Write a note on clinical manifestations of vitamin C deficiency. [2021/15m/3b]
Explain in detail the absorption and hormonal regulation of blood calcium in body. Discuss in brief the clinical manifestations of hypocalcemia. [2021/20m/4a]
Explain the role of vitamin-B₃ (Niacin) in biochemical processes. Write a note on its three main deficiency manifestations and the line of management. [2020/5m/2c(ii)]
Describe the synthesis and functions of Vitamin-D in the body. Write a note on the deficiency disorders along with relevant laboratory investigations and line of management. [2020/15m/4a(i)]
Explain the significance of selenium in biochemical processes. [2019/5m/2c(ii)]
Explain in detail the absorption and biochemical role of vitamin K in the body. Add a note on the deficiency manifestations of vitamin K along with relevant laboratory investigations for confirmation. [2019/10m/4a(i)]
What is the regulatory mechanism of iron absorption at the level of intestine? What is the role of TIBC in iron metabolism? How does the body conserve iron? [2018/10m/1c]
Describe briefly:
(i) Role of PCR (Polymerase Chain Reaction) in the diagnosis and management of Mycobacterium tuberculosis. [2018/7m/2c(i)]
(ii) Role of iodine in synthesis and function of thyroid hormone. What is Graves Disease? [2018/8m/2c(ii)]
What is folate trap? What are the methods of assessment of vitamin B₁₂ deficiency. [2018/7m/3b(ii)]
Describe how iron is absorbed, transported and stored in our body. Give the different tests done to assess status of iron in the body. [2017/20m/2a]
Justify the statement ‘Vitamin D is a hormone’. Describe the synthesis, mechanism of action and physiological functions of vitamin D. [2017/15m/4c]
Give the role of vitamin C in scurvy and cholesterol metabolism. [2016/10m/1e]
Outline the biochemical functions and the deficiency symptoms of sulphur-containing vitamins. [2016/15m/3c]
What are the main important functions of pyridoxine (vitamin )? Explain. [2015/20m/2a]
Discuss briefly: (i) Vitamin D resistant rickets (ii) Chromium as a trace element (iii) Role of plasma enzymes in evaluation of liver function. [2015/15m/3c]
Enumerate the various anti-oxidant vitamins and write about any one of them. [2014/10m/1e]
Avidin an egg protein has great affinity to a vitamin. Discuss the biochemical role of that vitamin. [2013/10m/1e]
Which mineral irreversibly inhibits glycolysis? Discuss clinical manifestations due to its deficiency and toxicity. [2013/20m/4b]
Describe the role of vitamins in prevention of Anaemia. [2012/20m/4a]
Nodular growth in neck is very common among population living in mountain areas. – Why? How will you investigate such cases? [2012/20m/4b]
Give the role of a micronutrient as a component of ‘glucose tolerance factor’. What is its RDA and deficiency manifestation? [2011/10m/1e]
Explain the effect of anticonvulsant drugs (Phenobarbital/diphenylhydantoin) on the vitamin requirements in the body. State the role that the relevant vitamin/vitamins play(s) in the human body. [2011/20m/4a]
What could be the nutritional deficiencies encountered in an ‘Alcoholic’ person? Explain the reasons clearly. [2011/20m/4c]
Chronic renal failure leads to Osteodystrophy. Outline the chain of events. [2010/12m/1f]
Substantiate the following statement: “Deficiency of a trace element leads to diminished glucose tolerance.” [2010/20m/4a]
The use of oral contraceptives appears to increase the requirement of a vitamin. Which vitamin is involved? Explain why. How is this identified clinically? [2010/20m/4b]
Describe the mechanism of mineralization of bone. Enumerate the clinical features of deficiency of the factor responsible for mineralization. [2007/20m/1d]
Enumerate with suitable examples vitamin coenzymes involved in oxidation-reduction reactions. Describe at least three vitamers. [2006/20m/4a]
Explain the biochemical role of vitamins in the prevention of megaloblastic anaemia. State their dietary sources. [2003/20m/200w/1d]
Write a transamination reaction. How is this reaction important in amino acid metabolism? Which vitamin is required in this reaction? [2001/20m/4a]
Explain why toxicity of vitamins is seen mainly with respect to fat soluble vitamins only. Describe different forms and roles of vitamin A. [1999/20m/2c]
Why are the trace elements called so? Enumerate the various trace elements required in human nutrition and mention their biochemical role. [1998/20m/2a]
Explain why excessive intake of fat soluble vitamins is toxic as compared to the water soluble vitamins. Describe the biochemical role of vitamin A. [1996/20m/3b]
Discuss the biochemical basis of different types of vitamin deficient anaemias. [1995/20m/3b]
3.4] Molecular techniques
21 questions
Discuss briefly the different steps of polymerase chain reaction (PCR) technique. Write three applications of PCR technique in clinical medicine. [2026/10m/4b(ii)]
Restriction Fragment Length Polymorphism has a number of applications in clinical medicine. Briefly state any three. [2025/5m/3b(ii)]
Explain the principle of radioimmunoassay (RIA) and outline its role in the diagnosis of thyroid disorders. Add a note on the advantages and disadvantages of this technique. [2025/10m/4b(i)]
Briefly describe the role of Restriction Fragment Length Polymorphism (RFLP) in DNA fingerprinting. [2024/10m/4b(ii)]
Explain the principle and steps of Polymerase Chain Reaction (PCR). Write its clinical applications. [2023/10m/3b(i)]
Explain the principle and applications of radioimmunoassay. [2022/10m/2c(ii)]
Discuss the principle and steps involved in Polymerase Chain Reaction (PCR). Mention any five of its applications in clinical medicine. [2021/10m/2c(i)]
Discuss the principle and the steps involved in Restriction Fragment Length Polymorphism (RFLP). Write any three applications of RFLP in clinical medicine. [2020/10m/2c(i)]
Discuss the principle and the steps involved in real time PCR. Enlist any five applications of PCR in medicine. [2019/10m/2c(i)]
Describe briefly:
(i) Role of PCR (Polymerase Chain Reaction) in the diagnosis and management of Mycobacterium tuberculosis. [2018/7m/2c(i)]
(ii) Role of iodine in synthesis and function of thyroid hormone. What is Graves Disease? [2018/8m/2c(ii)]
Describe the principle of Radio Immuno Assay (RIA). What are the main advantages and disadvantages of RIA technique. [2018/8m/3b(i)]
Discuss the principle of ‘Polymerase Chain Reaction (PCR)’ technology and outline the steps involved. Write its clinical application. [2017/15m/3c]
What is the basic principle behind the RFLP technique? Outline the clinical applications of RFLP. [2016/15m/4c]
Write in brief:– (i) Reverse transcriptase–P.C.R. (ii) Significance of S. enzymes in liver diseases. [2013/10m/4c]
Write in brief about: (i) Real time PCR (ii) Hepcidin (iii) VNTR (iv) Tag Polymerase. [2012/20m/4c]
How are deletions in ‘gene causing diseases’ detected? Explain in terms of Duchenne Muscular Dystrophy (DMD). [2010/12m/1e]
In 1977, Rosalyn Yalow was awarded the Nobel Prize in Medicine for innovating an important technique which was considered a breakthrough in endocrinology. What is this technique? Describe, briefly, the principle behind this technique. [2009/15m/1e]
What is real time polymerase chain reaction (rt. PCR)? How does it differ from regular polymerase chain reaction? How does this technique help to examine the single nucleotide polymorphism? [2009/20m/4c]
Outline the steps involved in recombinant DNA technology. State the applications in medicine. [2002/20m/200w/1d]
Discuss briefly basic procedure and clinical applications of polymerase chain reaction. [2001/20m/200w/5b]
Briefly describe the salient features of eukaryotic DNA. What is “Recombinant DNA”? In your opinion, how does the recombinant DNA technology find practical application in biology and medicine? [1998/20m/3a]
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Last updated: 31 October 2026