UPSC Prelims 2021 Question Paper & Analysis
Get the UPSC Prelims Previous Year Question (PYQ) Paper with subject-wise trends, difficulty analysis, and detailed model answers — including diagrams, flowcharts, and structured writing for GS.
Subject-wise MCQ Distribution
Difficulty Analysis
Type of questions
Key Insights
- Environment & Ecology, Indian Polity, Economy carried the highest weightage, together accounting for 51% of the paper.
- The paper strongly favoured statement-based questions — multi-statement and assertion-reasoning questions together made up 60% of the paper, making careful reading and elimination especially important.
- The paper was largely easy to moderate in difficulty, with 73% of questions falling in the easy or medium range and only 27% classified as hard.
- Questions were spread across 13 subject areas, making broad syllabus coverage important rather than relying on a few traditionally dominant subjects.
- The question format demanded more than direct recall, with only 40% of questions being direct, while most required evaluating multiple statements or reasoning through assertions.
PYQs with Detailed Answers
- View Answer for: Consider the following: Bacteria Fungi VirusWhich of the above can be cultured in artificial/synthetic medium?
Consider the following:
- Bacteria
- Fungi
- Virus
Which of the above can be cultured in artificial/synthetic medium?
- View Answer for: In the nature, which of the following is/are most likely to be found surviving on a surface without soil? Fern Lichen Moss MushroomSelect the correct answer using the code given below
In the nature, which of the following is/are most likely to be found surviving on a surface without soil?
- Fern
- Lichen
- Moss
- Mushroom
Select the correct answer using the code given below
- View Answer for: With reference to street lighting, how do sodium lamps differ from LED lamps? Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps. As street-lights, sodium lamps have longer life span than LED lamps. The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street lighting.Select the correct answer using the code given below
With reference to street lighting, how do sodium lamps differ from LED lamps?
- Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps.
- As street-lights, sodium lamps have longer life span than LED lamps.
- The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street lighting.
Select the correct answer using the code given below
- View Answer for: Which one of the following is a reason why astronomical distances are measured in light-years?
Which one of the following is a reason why astronomical distances are measured in light-years?
- View Answer for: Consider the following statements: Adenoviruses have single-stranded DNA genomes whereas retroviruses have double-stranded DNA genomes. Common cold is sometime caused by an adenovirus whereas AIDS is caused by a retrovirus.Which of the statements given above is/are correct?
Consider the following statements:
- Adenoviruses have single-stranded DNA genomes whereas retroviruses have double-stranded DNA genomes.
- Common cold is sometime caused by an adenovirus whereas AIDS is caused by a retrovirus.
Which of the statements given above is/are correct?
- View Answer for: Water can dissolve more substances than any other liquid because
Water can dissolve more substances than any other liquid because
- View Answer for: Bollgard I and Bollgard II technologies are mentioned in the context of
Bollgard I and Bollgard II technologies are mentioned in the context of
- View Answer for: With reference to recent developments regarding ‘Recombinant Vector Vaccines’, consider the following statements: Genetic engineering is applied in the development of these vaccines. Bacteria and viruses are used as vectors.Which of the statements given above is/are correct?
With reference to recent developments regarding ‘Recombinant Vector Vaccines’, consider the following statements:
- Genetic engineering is applied in the development of these vaccines.
- Bacteria and viruses are used as vectors.
Which of the statements given above is/are correct?
- View Answer for: Which one of the following is used in preparing a natural mosquito repellent?
Which one of the following is used in preparing a natural mosquito repellent?
- View Answer for: In the context of hereditary diseases, consider the following statements: Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of egg. A child inherits mitochondrial diseases entirely from mother and not from father.Which of the statements given above is/are correct?
In the context of hereditary diseases, consider the following statements:
- Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of egg.
- A child inherits mitochondrial diseases entirely from mother and not from father.
Which of the statements given above is/are correct?
- View Answer for: The term ‘ACE2’ is talked about in the context of
The term ‘ACE2’ is talked about in the context of
- View Answer for: In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following? Area of the hole in the lid. Temperature of the flame Weight of the lidSelect the correct answer using the code given below.
In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following?
- Area of the hole in the lid.
- Temperature of the flame
- Weight of the lid
Select the correct answer using the code given below.
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