This set covers the basics of biotechnology, from the structure of DNA to gene editing, vaccines and genetically modified crops. UPSC often frames questions on these topics around applications in health and agriculture, so the underlying concepts matter.
How to practise: read each question and tap the option you think is correct. You will see right away whether you got it, along with a short explanation, and your score is tracked at the bottom of the screen. This set has 15 questions.
Topics covered in this set
- DNA structure and base pairing
- Recombinant DNA, restriction enzymes and plasmids
- CRISPR-Cas9, PCR and DNA fingerprinting
- Vaccine platforms
- Stem cells and gene therapy
- GM crops, antibiotics and antivirals
UPSC Science and Technology MCQs with answers and explanations
Q1. The double helix model of DNA was proposed in 1953 by
a) Gregor Mendel and Charles Darwin
b) James Watson and Francis Crick
c) Louis Pasteur and Robert Koch
d) Har Gobind Khorana and Marshall Nirenberg
Q2. Which of the following is correct about nitrogen bases in nucleic acids?
a) In DNA, adenine pairs with guanine
b) RNA contains thymine in place of uracil
c) In DNA, adenine pairs with thymine and guanine pairs with cytosine
d) DNA contains uracil but RNA does not
Q3. In recombinant DNA technology, restriction enzymes are used to
a) join two DNA fragments together
b) copy DNA many times at high temperature
c) translate DNA into protein
d) cut DNA at specific recognition sequences
Q4. Why are plasmids widely used as vectors in genetic engineering?
a) They are small circular DNA molecules that replicate independently inside bacteria
b) They are proteins that carry genes into the nucleus
c) They are found only in human cells
d) They destroy foreign DNA entering a cell
Q5. Human insulin for diabetes is now mainly produced by
a) extracting it from the pancreas of cattle and pigs
b) inserting the human insulin gene into microbes such as E. coli
c) chemically synthesising it from glucose
d) growing human pancreatic tissue in laboratories
Q6. Which of the following is correct about CRISPR-Cas9?
a) It is a vaccine platform based on weakened viruses
b) It is a method of cloning whole animals
c) It uses a guide RNA to direct the Cas9 enzyme to cut DNA at a chosen site
d) It can only be used in bacteria
Q7. The polymerase chain reaction (PCR) is used to
a) sequence proteins
b) kill bacteria in blood samples
c) separate DNA fragments by size
d) make millions of copies of a specific DNA segment
Q8. Which of the following is correct about mRNA vaccines?
a) They give cells instructions to make a viral protein, which then triggers an immune response
b) They contain live, weakened virus
c) They permanently change the DNA of the person vaccinated
d) They contain ready-made antibodies
Q9. Covishield, used in India's COVID-19 vaccination drive, is an example of which vaccine type?
a) Inactivated whole-virus vaccine
b) Viral vector vaccine
c) mRNA vaccine
d) Live attenuated vaccine
Q10. Induced pluripotent stem cells (iPSCs) are produced by
a) taking cells from early embryos
b) fusing two adult cells
c) reprogramming adult body cells to an embryo-like state
d) extracting cells from umbilical cord blood only
Q11. Bt cotton is resistant to bollworm because
a) it has a thicker cell wall
b) it releases a smell that repels insects
c) its leaves contain high levels of nicotine
d) it carries a gene from Bacillus thuringiensis that produces a protein toxic to the pest
Q12. Golden Rice was genetically engineered to address which deficiency?
a) Vitamin A deficiency
b) Iron deficiency
c) Iodine deficiency
d) Vitamin C deficiency
Q13. Why are antibiotics not effective against the common cold?
a) The cold is caused by a fungus
b) The cold is caused by viruses, which lack the bacterial structures that antibiotics target
c) Antibiotics are destroyed in the respiratory tract
d) The cold is caused by an allergy, not an infection
Q14. Gene therapy aims to
a) replace a person's entire genome
b) treat diseases using only antibiotics
c) treat a genetic disorder by introducing a working copy of a gene into a patient's cells
d) change the blood group of a patient
Q15. DNA fingerprinting, used in forensic science, is based on
a) the number of chromosomes in a cell
b) the shape of red blood cells
c) differences in blood groups
d) differences in repetitive DNA sequences between individuals
Quick revision notes
- DNA is a double helix with A-T and G-C base pairing, and RNA uses uracil in place of thymine.
- Restriction enzymes cut DNA, DNA ligase joins it, and plasmids act as vectors in recombinant DNA technology.
- CRISPR-Cas9 uses a guide RNA to make targeted cuts in DNA (Nobel Prize in Chemistry, 2020).
- PCR amplifies DNA using heat-stable Taq polymerase.
- Covishield is a viral vector vaccine, Covaxin is an inactivated vaccine, and mRNA vaccines do not alter human DNA.
- Bt cotton carries a Cry gene from Bacillus thuringiensis, and Golden Rice produces beta-carotene.
Frequently asked questions
What is the difference between gene editing and genetic modification?
Genetic modification usually inserts a gene from another organism, as in Bt cotton. Gene editing, such as CRISPR, makes precise changes to an organism's own DNA. Some edits, like small deletions, leave no foreign DNA.
Why do antivirals work differently from antibiotics?
Viruses use the host cell's machinery to multiply, so antivirals target specific viral steps such as entry or replication enzymes. Antibiotics target structures found only in bacteria. This is why one class does not work against the other.
What are embryonic and adult stem cells?
Embryonic stem cells are pluripotent and can form almost any cell type. Adult stem cells, such as those in bone marrow, are usually multipotent and form a limited range of cells. iPSCs are adult cells reprogrammed to become pluripotent.
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