Acme Ai
A
अ
GS Paper IUPSC Prelims 2021
Biodiversity & Conservation
Question No. 31Interactive Test Mode
00:00
+2-0.66

Q31. 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?

Select the correct option below (or cross out options to eliminate)
PrevNext Question

Official Answer Key & Detailed Solution

3D PYQ Realm

Ready to check the official UPSC Answer Key?

Click any option above to test yourself under exam conditions, or reveal the explanation directly.

Official UPSC Answer KeyUPSC Prelims 2021 • Environment and Ecology

Correct Answer: Option (C) — Lemongrass

Concept & Option Breakdown

Standard Reference Verified

Option (c) is correct: Lemongrass (Cymbopogon species) contains essential oils rich in citronellol, geraniol, and citronellal, which are widely utilized as natural repellents against mosquitoes and other insects.

Reviewed by Avinash Sir & Acme AI Research Team

Practice Full-Length & Sectional Prelims Mocks on this Interface

50 simulated tests in the APT Prelims Test Series (₹1,493) or 1-on-1 Mentorship with Avinash Sir.

1-on-1 MentorshipOpen Test Platform

Question Specifications & Syllabus Mapping

Examination & YearUPSC Civil Services Preliminary Examination 2021 (Q31)
Paper & Marking SchemeGS Paper I • 2 Marks (-0.66 Negative for incorrect response)
Syllabus Subject & TopicEnvironment and Ecology → Biodiversity & Conservation
Official Answer KeyOption (C) — Lemongrass

More PYQs from Environment and Ecology (Biodiversity & Conservation)

Master the Environment and Ecology syllabus cluster by practicing these related previous year questions.

View All Environment and Ecology PYQs
2024 • Q24Biodiversity & Conservation

The organisms “Cicada, Froghopper, and Pond skater” are:

Environment and EcologyPractice
2023 • Q25Biodiversity & Conservation

Consider the following statements: Statement-I: Marsupials are not naturally found in India. Statement-II: Marsupials can thrive only in montane grass

Environment and EcologyPractice
2023 • Q26Biodiversity & Conservation

Consider the following fauna: 1. Lion-tailed Macaque 2. Malabar Civet 3. Sambar Deer How many of the above are generally nocturnal or most active afte

Environment and EcologyPractice
2023 • Q27Biodiversity & Conservation

Which of the following organisms perform waggle dance for others of their kin to indicate the direction and the distance to a source of their food?

Environment and EcologyPractice
2023 • Q28Biodiversity & Conservation

Consider the following statements: 1. Some microorganisms can grow in environments with temperature above the boiling point of water. 2. Some microorg

Environment and EcologyPractice
2023 • Q29Biodiversity & Conservation

Which one of the following makes a tool with a stick to scrape insects from a hole in a tree or a log of wood?

Environment and EcologyPractice
2023 • Q30Biodiversity & Conservation

Consider the following statements: 1. In India, the Biodiversity Management Committees are key to the realisation of the objectives of the Nagoya Prot

Environment and EcologyPractice
2021 • Q32Biodiversity & Conservation

The vegetation of savannah consists of grassland with scattered small trees, but extensive areas have no trees. The forest development in such areas i

Environment and EcologyPractice

Frequently Asked Questions — UPSC Prelims 2021 Q31

What is the official answer for UPSC Prelims 2021 GS Paper I Question 31 (Environment and Ecology)?

The official UPSC answer key for this 2021 Environment and Ecology (Biodiversity & Conservation) question is Option (C): "Lemongrass". Correct attempts carry 2 Marks with -0.66 Negative penalty for wrong answers.

Which UPSC Prelims syllabus topic does this 2021 question belong to?

This question belongs to GS Paper I under the subject "Environment and Ecology" and micro-topic "Biodiversity & Conservation". You can explore all repeated questions from Biodiversity & Conservation in Acme AI's 3D Prelims PYQ Realm or practice 50 full-length and sectional tests in the APT Prelims Test Series.

How can I solve this Biodiversity & Conservation UPSC Prelims question using option elimination?

To solve Biodiversity & Conservation questions in UPSC Prelims, identify extreme modifiers, verify core NCERT conceptual definitions, and eliminate mutually contradictory statement pairs before locking your final option.

Beyond Previous Year Questions

Structured Prelims Practice & Mentorship

Pair previous year question analysis with full-length simulated mock tests and 1-on-1 faculty guidance.

APT 2027 • 50 Prelims Tests17% OFF

Acme Prelims Test Series (APT)

Built to eliminate 1/3rd negative marking losses and 50–50 option traps through structured simulation and NCERT-backed keys.

  • 50 High-Yield Tests: Subject Sectionals, Current Affairs, CSAT Paper II & Full-Length Simulators
  • 1/3rd Penalty & Trap Analytics: Identify whether marks are lost to over-attempting or conceptual gaps
  • Option-by-Option NCERT Keys: Detailed distractor analysis and elimination logic for every question
  • Custom PDF-to-Mock Generator: Convert your revision notes or current affairs PDFs into practice tests
Complete 50-Test Package
₹1,493₹1,799• Valid till Prelims 2027
Explore APT Test SeriesTry Free Mock
1-on-1 Personal MentorshipCapped at 10 Seats

1-on-1 UPSC Mentorship with Avinash Sir

Weekly 1-on-1 strategy reviews, daily study accountability, and personalized MCQ attempt audits with an experienced UPSC mentor.

  • Weekly 1-on-1 Sessions: Direct mentorship with Avinash Sir (Former Plutus IAS Mentor, UPSC & UPPCS Mains Written)
  • APT 50-Test Series Included: Full Prelims GS1 & CSAT test series bundled at no additional cost
  • Mock Attempt & Elimination Audit: Question-by-question review to calibrate your risk and attempt accuracy
  • Prelims & Integrated Tracks: Available as dedicated Prelims mentorship or end-to-end Prelims + Mains guidance
Prelims & Integrated Tracks
17% OFF• Includes APT 50-Test Series
Explore 1-on-1 MentorshipCompare Tracks
Previous QuestionWhat was the exact constitutional status of India on 26th January, 1950?
Next QuestionThe vegetation of savannah consists of grassland with scattered small trees, but extensive areas have no trees. The forest development in such areas is generally kept in check by one or more or a combination of some conditions. Which of the following are such conditions? 1. Burrowing animals and termites 2. Fire 3. Grazing herbivores 4. Seasonal rainfall 5. Soil properties Select the correct answer using the code given below.