1. Science-tech= “D” Option Guess-mastergiriTM
  2. Trend analysis of the Sci-Tech Qs in UPSC prelim exams?
  3. Biology: Basic Theory MCQs asked in UPSC Prelims-2020
  4. Biotech MCQs in UPSC Prelims-2020 Answer Key
  5. Counter-view: 2nd statement wrong answer should be “C”
  6. ICT & Electronic Gadgets
  7. Counter-view: 5th statement wrong and Q shd be cancelled
  8. Space Technology
  9. Physics / electricity

Science-tech= “D” Option Guess-mastergiriTM

analysis of  science and technology answer key for UPSC Prelims 2020

Since most students want  shortcuts without hard work, and e-learning thugs want pageviews and followers. So, they are peddling this new rule of “Guess-master GiriTM / meta keyword analysis that says:

“In science technology MCQs, if you cannot solve the answer, then simply tick “D” option.”

Let’s quickly check the validity of this:

Year No. of Science MCQs were “D” is the right Answer NET GAIN or NET LOSS?
2020 7 out of 11 MCQ= 63%* (7*2)-(4*0.66)=+11.36
2019 2 out of 11 MCQs = 19% -1.94
2018 5 out of 13 MCQs = 38% +4.72
2017 2 out of 6 MCQs = 33% +1.36
  • *For 2020 exam, the official answer key is yet to be declared. For the remaining exams, I have used the official UPSC answer key.
  • Thus, if a candidate is unsure about a particular MCQ in science technology, and gives D as the answer, then overall he may gain a few marks, except the 2019 paper.
  • I do not like peddling this type of hacks/cheat codes/shortcuts. But I have mentioned this phenomenon here so that UPSC examiner can take cognizance of this matter and frame better quality of questions next year.
  • ✋and No, I donot make any claims that →
    • A) In future exams also this “Science = D Answer” will be equally useful OR that
    • B) You should stop studying science technology and engage in this type of shortcuts!

Trend analysis of the Sci-Tech questions in UPSC prelim exams?

Science-Tech in 2015 to 2019 Prelim Papers 2020 Prelims: Continuity and change in the Science-Tech questions
2019: Last year 11 questions asked While the number of questions same (11), but difficulty level increased
Less MCQs from theory, more from contemporary issues Same.
2019: Number of MCQs: Biotech > ICT > Physics similar
In 2019 paper: 5 science MCQs were one liner. i.e. Question and directly ABCD option given Only 3 science MCQs were ‘one liner’. Rest of them- Two statements, Three statements, Five statements given and you have to find the correct statements! So it was more time consuming and mentally exhaustive.
Virus used to be a favorite topic. Asked about H1N1, Ebola, Zika etc No question on virus despite coronavirus! 
2019 asked about

  1. Microbial pathogens drug resistance
  2. Hepatitis vaccine
  3. Even in past there have been questions related to biotechnology Medical Research such as CRISPR technology, gene silencing therapy  etc.

  1. Pneumococcal vaccine & Drug resistance
  2. Utility of carbon nanotubes in biotech asked
ICT “service technology” asked: NFC, Project Loon, LIFI, LTE vs VOLTE Again asked about LIFI (VLC Technology)
Ask about Electronics gadgets / technology like GPS, 3D printer, Internet of things (IoT), Augmented reality vs virtual reality, Wearable devices Asked about gadgets- Drones
2017: asked about ELISA. But it was a much easier because simply 1 word association asked “Elisa= Detecting gravitational waves” 2020: again asked, But this time in the much tougher manner.
Cyber security related organisations / provisions asked. Wannacry Ransomware, Digital signature Trend continued
Questions from the pure physics such as -light and gravity, string theory, Magnetic field of the earth, Blackholes etc. = pure Class-11-12 Physics book type theory. Application / research based science technology asked. So, command over Class-11-12 Physics theory, not very useful. So, the cynicism on negativity that paper was more friendly towards the IIT/JEE/NEET type crowd- may be in some cases but NOT entirely.
Sometimes asked about ISRO/India space satellite exploration related Qs such as IRNSS nothing from ISRO
2019: Ask about Caveman fossils  (आदिमानव के अवशेषों के बारे में) ●       Thankfully that “Fossil-Tamasha is NOT asked.

●       God forbid, if tomorrow UPSC asks a question about dinosaur fossils (Since the Hindu writes  50 articles on each every year)  then, some of the e-Learning channels will create a separate “subject” out of it “Dinosaur fossils Compilation”, Just like they have invented a new subject “PIB Compilation”!

Was the paper more friendly towards the IIT-JEE/NEET crowd?

  • If you look at theory questions like “Plant cell versus Animal cell”, You may feel it is more friendly towards the Science / Engineering crowd.
  • However, the nature of the many science-tech questions was such that research level topics were asked. Not directly given in books. Even private answer keys vary depending on which research paper they use for solving the MCQ.
  • So, paper can’t be said to be “fully IIT-JEE/NEET/ Class 11-12-PCM friendly”. Because their pure theory is not automatically useful in each and every question. . यह जरूरी नहीं है कि IIT-वाला हर science का जवाब सही से ठीक कर के आया, क्योंकि बहुत सारे MCQ ऐसे थे जो सीधे-सीधे किताब में है ही नहीं
  • I am saying it here, because when the UPSC Prelim result will be out, many of the failed-candidates will blame “IIT/NEET/B.Sc Agriculture -walle took my seat.” But you should also introspect on what other mistakes you had made in the paper by yourself & fix it in the next attempt.
  • Besides, do not expect competitive exams to be full of justice and unbiased towards every stream. The UPSC is not going to give the ready-made things on a platter to you. You will have to work for it (And hope that luck is also on your side!)
  • So, if a Commerce / Arts / MBA student is thinking, “I’ll ignore Sci-Tech and make up the deficit through Environment, Polity, Economy, History-Culture.” Well, then he’s making a mistake because those topics are not getting any easier.

“General Science observation” APOLOGISTs & their SAPNA Theory

  • Nehru apologists cannot find any fault in Prime Minister Nehru’s policies.
  • Modi apologists cannot find any fault in Prime Minister Modi’s policies.
  • Similarly UPSC’s “General Science observation” APOLOGISTs, typically say the following: “Because we use the water pump sets and therefore UPSC asked a tricky question from whether solar energy can be used for submersible pump or not?…It is all about general observation from your day today life around you. – इसलिए आपको सपना आ जाना चाहिए था की ये सब पूछा जानेवाला है. IQ nhi EQ chaahiye…” 
  • …. Bhai Given such a large Syllabus of UPSC, who has the time to bring his head out of the books and PDF files, to go around the world and observe everything like Sheldon Cooper?
  • So I do not subscribe to their theories.

Utility of theHindu newspaper?

  • The scene is similar to the agriculture questions asked in UPSC Prelims 2020
  • Basically some questions may be solved but it requires you to go back to the newspapers of 2016 and 17 which is normally not possible for candidates at present. So for answers, I am not crediting theHindu आपको सपना आ जाना चाहिए था की 2016-2017 के  अख़बार से ये सब पूछा जानेवाला है.

Utility of current affairs pdf files?

  • While they cover the science technology in great detail in their monthly free current affair PDF files but Only 1 out of the 11 MCQs could be solved- ‘Pronuclear transfer’.
  • For remaining questions, A) either the material was not available, or B) it was not giving the particular information which is asked in the MCQ.
  • At the same time, it doesn’t mean you should stop reading it all together. You should glance over it just to be familiar with what has been happening around. Save the time and trouble of not having to maintain your own notes out of newspapers.
  • ✋But at the same time you should not be spending a disproportionate amount of your time in current affairs.

Prelims-2021 Strategy: Science Theory

  • Way back in 2013-14, UPSC asked very silly and easy questions from science like name of diseases caused by Vitamin deficiency. So, NCERT (Class7-10) + LucentGK type combo would have sufficed.
  • But in recent exams, hardly any direct questions are coming from there
  • For example, Newton’s laws, laws of electricity, friction and optics, various uses of basic chemicals ….nothing is asked in recent years. Therefore, going through bulky General Studies Manuals = poor cost benefit.
  • Yes you should be familiar with those Basic concepts (Newton’s laws etc.) because They may indirectly help you in elimination of some wrong options And also in the other exams such as CDS,CAPF, StatePSC,SSC.
  • but in the NCERT you should focus more on study of chapters / topics having relevance with environment, agriculture, public health, biotech, space and ICT/communication.

Prelims-2021 Strategy: Science Current Affairs & Contemporary Affairs

  • While preparing science Current/Contemporary affairs, the target areas should be: Environment, Agriculture, Public Health, Biotech, ICT/communication and Space.
  • Within Space, first priority to ISRO than NASA, then other countries and lastly to the randomly discovered stars and planets.
  • Go through the science technology questions asked in the previous years. Because
    • 1) sometimes the themes / wrong options are again asked (e.g. CAS9). And
    • 2) at least it gives you a rough idea in defining the boundary of your syllabus and preparation for science-tech.
  • Contemporary Affairs (ie. topics older than one year): Book such as Ravi Agrahari and/or
  • Current Affairs (i.e. 1/1/2019 onwards): Free PDF compilations- whichever catches your fancy (VisionIAS, IASparliament etc).
    • While such PDF compilations have given very little utility / benefit in Prelim-2020’s Science-Tech portion, as if UPSC examination had carefully monitored them and carefully avoided asking anything given it.
    • But, the opposite strategy that,” I will prepare my super speciality notes on science technology from newspapers directly!” = poor cost:benefit, because:
    • 1) For majority of the topics in your handmade notes will overlap with those freely available PDF compilations.
    • 2) To think like a UPSC examiner, first you will have to go through all PDF compilations then compare them with the newspaper, then identify which topic is not covered there, so you will make a super speciality note on it. This is impracticable and complete waste of time. Because such minutes things from Sci-tech are not asked in Mains. Besides cutoff is never 200/200 marks and your Prelim score is not counted in the final selection.
  • Read theHindu / IndianExpress daily: Make notes from it Only If you’ve a very compelling reason to do so, e.g. This quotation or case study is very useful for the mains/essay/ethics/optional paper; or This news-item from my graduation subject / homeState/ Hobby / Employer-Company may be asked in an interview.

How to prepare Science for UPSC Mains-2021 (GSM3)?

  • Mains General Studies Paper 3 (GSM3): Topic wise past questions & strategy for Science Tech has already been given in the following article: Click Me.
  • To conclude, there is no rocket science or secret formula to crack the science questions in IAS prelims. You prepare what you can, and then focus on the other subjects. जितना खुद से पढ़ सकते हो वह पढ़ो. फिर दूसरे विषयों की तैयारी करो. पूरा दिन इसको लेकर मत बैठे रहो. ✋

Anyways let’s now solve the science technology questions asked in UPSC Prelims 2020

Biology: Basic Theory MCQs asked in UPSC Prelims-2020

(Pre’20-SetB) Q.07. Which of the following statements are correct regarding the general difference between plant and animal cells ?

  1. Plant cells have cellulose cell walls whilst animal cells do not.
  2. Plant cells do not have plasma membrane unlike animal cells which do.
  3. Mature plant cell has one large vacuole whilst an animal cell has many small vacuoles.

Select the correct answer using the code given below :

[a) 1 and 2 only

[b) 2 and 3 only

[c) 1 and 3 only

[d) 1, 2 and 3

Difficulty : Easy ? Directly given in the NCERT textbooks.

Type: Theory ?


  • NCERT Class10 Science: page 61– Plant cells, in addition to the plasma membrane, have another rigid outer covering called the cell wall. So, statement#2 is incorrect, so by elimination answer is C.

? GuessMaster-GiriTM: ??Anti-GuessMaster.  If you believe in the rule#6 that in science-technology questions, more than often, the answer is “D/ All statements correct”. 

Biotech MCQs in UPSC Prelims-2020 Answer Key

(Pre’20-SetB) Q.17. In the context of recent advances in human reproductive technology, ‘Pronuclear Transfer” is used for

[a) Fertilization of egg in vitro by the donor sperm

[b) Genetic modification of sperm producing cells

[c) Development of stem cells into functional embryos

[d) Prevention of mitochondrial diseases in offspring

Difficulty :  Medium ?  toTough ? This is asked from 2016 current affair about three parent baby. Although in 2019, CA-PDFs such as Vision/Shankar etc had covered it, So depending on your memory and recollection power, you may have ticked.

Type: Contemporary ?


  • 2016-TheHindu: Pronuclear transfer technology was used for creation of a “three-parent baby” — It has DNA from 1) father 2) mother 3) female donor- so as to prevent mitochondrial disease.

(Pre’20-SetB) Q.05. What is the importance of using Pneumococcal Conjugate Vaccines in India?

  1. These vaccines are effective against pneumonia as well as meningitis and sepsis.
  2. Dependence on antibiotics that are not effective against drug-resistant bacteria can be reduced.
  3. These vaccines have no side effects and cause no allergic reactions.

Select the correct answer using the code given below :

[a) 1 only

[b) 1 and 2 only

[c) 3 only

[d) 1, 2 and 3

Difficulty : Tough ? Because routine preparation sources  are only mentioning this vaccine is given under the universal immunization programme but beyond that sufficient information is not available within a single source to validate the statements.

Type: Contemporary ? Because it was first introduced in the year 2000 in USA


  • As per Google books: It is 80% effective against meningitis, sepsis and pneumonia → #1 is right.
  • Pneumococcal b conjugate vaccines have reduced the burden of antibiotic-resistant bacterial disease globally says the Lancet study-report 2017 → #2 is right. We are ? 50:50 between B or D.
  • Various research papers have indicated that vaccine may cause certain side effects and allergic reactions so, #3 is wrong. Accordingly, Answer is B

? GuessMaster-GiriTM: ?Partially Possible. If you believe in the rule#1 that extreme worded statements are always wrong  → Then the third statement should be wrong because it contains extreme words “No side effects and no allergic reactions”. Then We are ? 50:50 between A or B.

? GuessMaster-GiriTM: ??Anti-GuessMaster. If you believe in the rule#6 that in science-technology questions, more than often, the answer is “D: All statements correct”. 

(Pre’20-SetB) Q.01. With reference to the carbon nanotubes, consider the following statement :

  1. They can be used as the carriers of drugs and antigens in the human body.
  2. They can be made into artificial blood capillaries for an injured part of human body.
  3. They can be used in biochemical sensors.
  4. Carbon nanotubes are biodegradable.

Which of the statements given above are correct ?

[a) 1 and 2 only

[b) 2, 3 and 4 only

[c) 1, 3 and 4 only {?}

[d) 1, 2, 3 and 4

Difficulty : Tough ? All statements are not available in a single place

Type:   Contemporary ? It was invented in the year 1991, so it’s not theory.


  • 2019-Sept: Delhi researchers have made a carbon nanotube based sensor for detecting cancer cells, says theHindu So, #3 is right. Option-A is eliminated. In all the remaining options, statement#4 is common, so We have to accept it as correct without checking.
  • For biomedical applications, carbon nanotubes show promise as vehicles for targeted drug-delivery and nerve cell regeneration. says Britannica so #1 may be true. → We are ? 50:50 between C or D.
  • Some of the research paper say that Artificial blood vessels could be made so answer should be “C”.

Counter-view: Second statement wrong answer should be “C”

  • 2015: Research paper from Dublin says that Using carbon nanotube as an artificial blood vessel can create blood clotting Therefore it is unsafe. If we believe this, then #2 wrong → Answer should be “C” ELSE answer should be “D”.
  • Final judge: we’ve to wait for UPSC’s Official answer key.

(Pre’20-SetB) Q.04. Consider the following statements :

  1. Genetic changes can be introduced in the cells that produce eggs or sperms of a prospective parent.
  2. A person’s genome can be edited before birth at the early embryonic stage.
  3. Human induced pluripotent stem cells can be injected into the embryo of a pig.

Which of the statements given above is/are correct ?

[a) 1 only

[b) 2 and 3 only

[c) 2 only

[d) 1, 2 and 3

Difficulty : Tough ? Because all statements are not easily available within a single source.  And those from non science graduation may face difficulties in deciphering the statements.

Type: Contemporary ?


  • 2017’s theHindu article says that CRISPR genome editing tool can be used for accomplishing statement#1. So, We are ? 50:50 between A or D.
  • 2020-May: AsiaTimes says that #3 was done in China. So, #3 is correct, We are left with the answer “D”.
  • Recall that in 2018 too, UPSC had asked a question from CRISPR genome editing Technology but it was a much simpler one liner question.

? GuessMaster-GiriTM: ?Fully Possible. If you believe in the rule#6 that in science-technology question, more than often, the answer is “D: All statements correct”. 

ICT & Electronic Gadgets

(Pre’20-SetB) Q.18. With the present state of development, Artificial Intelligence can effectively do which of the following?

  1. Bring down electricity consumption in industrial units
  2. Create meaningful short stories and songs
  3. Disease diagnosis
  4. Text-to-speech conversion
  5. Wireless transmission of electrical energy

Select the correct answer using the code given below:

[a) 1, 2, 3 and 5 only

[b) 1, 3, and 4 only {?}

[c) 2, 4, and 5 only

[d) 1, 2, 3, 4 and 5

Difficulty : Easy ? by general visualization about A.I.

Type: Contemporary ?


  • As per the articles published in Time.com and theverge, AI has been used for writing songs and stories → #2 is correct.
  • I. can be used for speech-to-text and text-to-speech, assistive diagnostic solutions; → #3 #4 are correct. Say Niti Aayog document page 81
  • Only in the d option 2, 3 and 4 are together so answer should be “D”

Counter-view: Fifth statement is wrong and question should be cancelled

  • Statement#5 is a different branch of science all together, unrelated to computer technology. wireless electricity/power transfer involves a transmitter that converts AC into a magnetic field. The device picks up the field and converts it back to AC. Nikola Tesla was Experimenting on it in 1899. says Britannica.
  • Using ‘Artificial Intelligence’ Technology this transfer can be regulated in better manner. But “Regulation by A.I.” as not the same as “A.I. itself transmitting the energy by something inside it. It’s like saying Smartphone itself can do heart surgery.” So, #5 not related with A.I. By elimination the answer should be “B“.
  • But in the “B” option, statement#2 is missing even though #2 is right,
  • So, it means all options are wrong. And this question should be cancelled. Ultimate judge- UPSC Answer Key. We have to wait and see how they interpret this?

(Pre’20-SetB) Q.19. With reference to visible light communication (VLC) technology, which of the following statements are correct?

  1. VLC uses electromagnetic spectrum wavelengths 375 to 780nm
  2. VLC is known as long-range optical wireless communication
  3. VLC can transmit large amounts of data faster than Bluetooth
  4. VLC has no electromagnetic interference

Select the correct answer using the code given below

[a) 1, 2 and 3 only

[b) 1, 2 and 4 only

[c) 1, 3 and 4 only

[d) 2, 3 and 4 only

Difficulty : Medium ?. It’s basically related to LIFI technology, which has been asked in the past Prelims as well. But you can tick it, only if you know that LIFI works on VLC.

Type: Contemporary ? Li-fi is a contemporary  topic since 2015


  • Li-Fi is a Visible Light Communications (VLC) system for running wireless communication. Li-Fi’s main disadvantage: It is effective for short range only. Says, Ravi Agrahari’s Book, chapter14 on the Internet.
  • So, #2 is wrong. By elimination, the answer is “C”.

? GuessMaster-GiriTM: ??Anti-GuessMaster.  If you believe in the rule#1 that extreme worded statements are always wrong  → Then Forth statement should be wrong because it contains extreme word “has no electromagnetic interference”  → But then by elimination, you will arrive at wrong answer “A”

? GuessMaster-GiriTM: ??Anti-GuessMaster. If you believe in the rule#6 that in science-technology questions, more than often, the answer is “D: All statements correct”. 

(Pre’20-SetB) Q.06. In India, the term “Public Key Infrastructure” is used in the context of

[a) Digital security infrastructure

[b) Food security infrastructure

[c) Health care and education infrastructure

[d) Telecommunication and transportation infrastructure

Difficulty : Easy ? Public key authentication, digital signature -these are recurring themes asked in the UPSC exams.

Type: Contemporary ?


  • Ravi Agrahari Science Tech Ch. 15:
  • India is among those few nations that have the Digital Signature Legislation.
  • Digital signatures deploy the Public Key Infrastructure (PKI) technology.

? GuessMaster-GiriTM: ??Anti-GuessMaster. If you believe in the rule#6 that in science-technology questions, more than often, the answer is “D/All statements correct”.

(Pre’20-SetB) Q.02. Consider the following activities :

  1. Spraying pesticides on a crop field
  2. Inspecting the craters of active volcanoes
  3. Collecting breath samples from spouting whales for DNA analysis

At the present level of technology, which of the above activities can be successfully carried out by using drones ?

[a) 1 and 2 only

[b) 2 and 3 only

[c) 1 and 3 only

[d) 1, 2 and 3

Difficulty: Medium ?  Because all three statements are not available within one place. Although relatively easier than carbon nanotubes because you can use some imagination.

Type: Contemporary ?


  1. 2019-Dec: Drone used for spraying pesticides on a crop field says  theHindu#1 is correct.
  2. 2020-June: Drone can be used for monitoring active volcanoes, says Science USA news
  3. 2019-Feb: Drones can be used for doing statement#3, says reuters.com article
  4. So all three correct

? GuessMaster-GiriTM: ?Fully Possible.  If you believe in the rule#6 that in science-technology questions, more than often, the answer is “D/ All statements correct”. 

Space Technology

(Pre’20-SetB) Q.03. The experiment will employ a trio of spacecraft flying in formation in the shape of an equilateral triangle that has sides one million kilometres long, with lasers shining between the craft.” The experiment in question refers to

[a) Voyager-2

[b) New Horizons

[c) LISA Pathfinder

[d) Evolved LISA

Difficulty: Tough ? Because candidates prepare the ISRO’s missions in great detail but this is a non-ISRO space mission where UPSC asked Technical details.

Type: Contemporary ?


  • Ravi Agrahari’s Science and Tech book Chapter10 on Space research:
    • 1977: NASA’s Voyager’s aimed to probe Jupiter, Saturn, Uranus and Neptune. Returned pictures and data.
    • 2006: NASA’s New Horizons spacecraft’s primary objective was to make a fly-by study of the Pluto system
  • Since Voyager 2 and New Horizons are 1-1 space crafts. So A and B are gone. We are ? 50:50 between C or D.
  • LISA Pathfinder aimed to study gravitational waves.
  • 2016’s thehindu Article gives a description about Evolved LISA fitting the question statement. So, D answer.

Physics / electricity

(Pre’20-SetB) Q.68. With reference to solar water pumps, consider the following statements:

  1. Solar power can be used for running surface pumps and not for submersible pumps,
  2. Solar power can be used for running centrifugal pumps and not the ones with piston.

Which of the statements given above is/are correct?

[a) 1 only

[b) 2 only

[c) Both 1 and 2

[d) Neither 1 nor 2

Difficulty :  Medium ? to tough Prima facie it appears to be a question related to “Solar/Clean Energy” so it should be classified under the Environment. But it requires understanding of physics / electronics / Motor mechanism / Mechanical engineering. So I have put it under the Science-Tech category.

Type: Contemporary ?


  • As such many candidates would have simply applied to some “guess-work” that yes solar energy could be used for running all type of pumps. While it may turn out to be correct in this answer, but it is not necessary that in all the Physics and electronics principles it will turn out to be correct. e.g. what if Piston pumps worked only using diesel and not electricity? We cannot say for sure without studying, that every time our guess will turn out to be right.
  • As per Google Books-Ref#1: Some solar submersible pumps use a centrifugal mechanism as a surface pump, While others use a positive displacement mechanism. So that means statement#1 is WRONG, and second#2 is partially correct.
  • As per Google Book-Ref#2: Has given a chapter on solar powered piston pump systems that can pump water from a well and delivers it to an elevated Storage tank. #2 is wrong.

? GuessMaster-GiriTM: ?Partially Possible.  If you believe in the rule#6 that in science-technology questions, more than often, the answer is “D/ All statements correct”. Then, Answer could be D- both wrong or C Both right. So, you’re @50:50. 


  1. Same as what I said in the economy Prelims-2020 Answerkey.
  2. Next we will see the History, Art & Culture Questions asked in Prelims-2020.
  3. Any errors? let me know in the comment section!
  4. Also my thanks to Shri Brijesh Patel (Faculty, SPIPA, Ahmedabad) for his assistance in preparation of this answer key.

Stay Tuned for the Detailed Answerkeys with Explanations at Mrunal.org/prelims