Genetic Engineering and Biotechnology

VidyaarOctober 24, 20260225 views

Q150. Consider genetic medicines:
1. They can correct or compensate for defective genes.
2. Engineered viruses and lipid nanoparticles may deliver them.
3. They always rewrite the entire genome.

Which are correct?

[UPSC CSE (Pre) 2026]

(a) 1, 2 and 3
(b) 1 and 2 only
(c) 1 only
(d) 2 and 3 only

Answer: (b) 1 and 2 only

Explanation: Genetic medicines address particular genes or their products rather than rewriting all chromosomes. Engineered viral vectors and lipid nanoparticles help deliver therapeutic genetic material into cells. Therefore the first two statements are correct, while the third is an overgeneralisation.

Q149. What is the fundamental hereditary material of most cellular organisms?

[UPSC CSE — Practice]

(a) DNA
(b) Glycogen
(c) Cellulose
(d) ATP

Answer: (a) DNA

Explanation: DNA stores inherited biological instructions through the sequence of its nitrogenous bases. It is replicated and transmitted during cellular division. RNA is the genetic material in some viruses, but most cellular organisms use DNA as their principal information-bearing molecule.

Q148. Which nucleotide base pairs with adenine in ordinary double-stranded DNA?

[WBCS — Practice]

(a) Guanine
(b) Uracil
(c) Cytosine
(d) Thymine

Answer: (d) Thymine

Explanation: In standard DNA, adenine pairs with thymine through two hydrogen bonds, while guanine pairs with cytosine through three. Complementary base pairing permits faithful replication and accurate copying of genetic information across generations.

Q147. Which sugar is present in the backbone of DNA?

[MPPSC — Practice]

(a) Sucrose
(b) Ribose
(c) Deoxyribose
(d) Fructose

Answer: (c) Deoxyribose

Explanation: DNA nucleotides contain the pentose sugar deoxyribose, a phosphate group and a nitrogenous base. RNA instead generally contains ribose. The absence of an oxygen at the second carbon helps distinguish deoxyribose chemically.

Q146. A DNA nucleotide consists of which three components?

[UPPCS — Practice]

(a) Protein, cholesterol and phosphate
(b) Sugar, phosphate and nitrogenous base
(c) Glucose, water and enzyme
(d) Amino acid, lipid and sugar

Answer: (b) Sugar, phosphate and nitrogenous base

Explanation: A nucleotide contains one pentose sugar, one or more phosphate groups and a nitrogenous base. Joining nucleotides through phosphodiester bonds produces a polynucleotide. The base sequence carries information, while the sugar-phosphate backbone provides structural continuity.

Q145. Regarding the GenomeIndia Project, assess:
1. It forms part of the Human Genome Project.
2. It is funded by India’s Department of Biotechnology.
3. It catalogues genetic diversity in Indian populations.

Which statements are correct?

[UPSC CSE (Pre) 2026]

(a) 2 and 3 only
(b) 1 only
(c) All three
(d) 1 and 2 only

Answer: (a) 2 and 3 only

Explanation: GenomeIndia is a distinct Indian initiative supported by the Department of Biotechnology. It aims to document genomic variation across Indian populations and support research in health and ancestry. It is not a subdivision of the earlier international Human Genome Project.

Q144. Two strands in the usual DNA double helix run in which orientation?

[RAS / RPSC — Practice]

(a) Perpendicular
(b) Parallel 5-prime to 3-prime
(c) Randomly branched
(d) Antiparallel

Answer: (d) Antiparallel

Explanation: The complementary DNA strands run in opposite chemical directions, one 5-prime to 3-prime and the other 3-prime to 5-prime. This antiparallel organisation allows regular base pairing and is essential to how DNA polymerases copy the strands.

Q143. Which nitrogenous base is usually found in RNA instead of thymine?

[SSC CGL — Practice]

(a) Adenine
(b) Guanine
(c) Uracil
(d) Cytosine

Answer: (c) Uracil

Explanation: RNA generally uses uracil where DNA uses thymine. Both molecules also contain adenine, guanine and cytosine. Although this is a useful distinction, several modified bases occur in specialised RNA molecules and certain unusual nucleic acids.

Q142. DNA replication is called semiconservative because each daughter molecule contains:

[SSC CHSL — Practice]

(a) Only fragments of parental strands
(b) One original strand and one newly synthesised strand
(c) Two completely newly synthesised strands
(d) Three DNA strands

Answer: (b) One original strand and one newly synthesised strand

Explanation: Semiconservative replication preserves one parental template strand in each daughter double helix, paired with one newly synthesised complementary strand. Meselson and Stahl experimentally demonstrated this mechanism using nitrogen isotopes in bacterial DNA.

Q141. Which chemical bond connects successive nucleotides along one DNA strand?

[SSC MTS — Practice]

(a) Phosphodiester bond
(b) Peptide bond
(c) Hydrogen bond
(d) Disulfide bond

Answer: (a) Phosphodiester bond

Explanation: A phosphodiester linkage connects the 3-prime hydroxyl of one sugar with the 5-prime phosphate of the next nucleotide. Hydrogen bonds join opposite complementary bases, whereas peptide bonds connect amino acids in proteins.

Q140. Regarding monoclonal antibodies, assess:
1. They are laboratory-produced proteins.
2. Specific antigen binding can support immune functions.
3. Antibody candidates have been used investigationally against Nipah infection.

Which are correct?

[UPSC CSE (Pre) 2025]

(a) 2 and 3 only
(b) 1 and 2 only
(c) 1 and 3 only
(d) All three

Answer: (d) All three

Explanation: Monoclonal antibodies are produced from selected cell lines or engineered systems and recognise particular antigens. They have therapeutic applications against several diseases. Investigational antibody m102.4 has also been explored for Nipah virus infection; none of this implies a licensed cure for Nipah.

Q139. Which enzyme synthesises DNA using a DNA template during ordinary replication?

[RRB NTPC — Practice]

(a) Protease
(b) Cellulase
(c) DNA polymerase
(d) RNA ligase

Answer: (c) DNA polymerase

Explanation: DNA polymerase adds deoxyribonucleotides to a growing DNA chain using a template strand. Synthesis proceeds in the 5-prime to 3-prime direction. Depending on organism and polymerase, proofreading activities reduce errors during genome copying.

Q138. What is a zygote?

[RRB Group D — Practice]

(a) A cell produced by meiosis after birth
(b) A cell formed by fusion of gametes
(c) An unfertilised ovum only
(d) A mature pollen grain

Answer: (b) A cell formed by fusion of gametes

Explanation: A zygote forms when male and female gametes fuse during fertilisation. It normally contains genetic contributions from both parents and undergoes subsequent mitotic divisions during early development. In humans, it is the first diploid cell of the new individual.

Q137. Restriction endonucleases are useful in biotechnology because they:

[CGPSC — Practice]

(a) Recognise and cut specific DNA sequences
(b) Join protein chains
(c) Destroy all RNA in a cell
(d) Convert DNA into lipids

Answer: (a) Recognise and cut specific DNA sequences

Explanation: Restriction endonucleases recognise particular DNA sequences and cleave phosphodiester bonds at or near those sites. Their selective cutting enables isolation of DNA fragments and assembly of recombinant molecules. Many originated as bacterial defences against foreign genetic material.

Q136. Which enzyme is used to join two compatible DNA fragments into a stable molecule?

[UPSC CDS — Practice]

(a) Pepsin
(b) Topoisomerase only
(c) Amylase
(d) DNA ligase

Answer: (d) DNA ligase

Explanation: DNA ligase seals nicks in DNA by forming covalent phosphodiester links between adjoining ends. When compatible fragments are positioned together, ligase helps produce stable recombinant DNA. The enzyme is also important in normal cellular repair and replication.

Q135. Which among the following human hormones was the earliest to be manufactured commercially through recombinant DNA technology?

[Uttarakhand PCS (Pre) 2024]

(a) Oestrogen
(b) Thyroxine
(c) Insulin
(d) Testosterone

Answer: (c) Insulin

Explanation: Recombinant human insulin was the first human therapeutic hormone produced using genetic engineering and approved for widespread medical use in 1982. The product Humulin replaced dependence on animal-derived insulin and showed that microorganisms could manufacture human proteins.

Q134. The principal purpose of a cloning vector is to:

[UPSC NDA — Practice]

(a) Form chloroplast pigments
(b) Transport a DNA insert into a suitable host
(c) Maintain blood pressure
(d) Break down proteins in a test tube

Answer: (b) Transport a DNA insert into a suitable host

Explanation: A cloning vector carries a foreign DNA fragment into a host and enables its maintenance or replication. Engineered plasmids, bacteriophages and artificial chromosomes can serve as vectors. Useful vectors typically possess replication elements and selectable markers.

Q133. The ori sequence of a bacterial plasmid is required primarily for:

[State PSC — Practice]

(a) Initiation of DNA replication
(b) Antibiotic synthesis
(c) Cell wall breakdown
(d) Protein degradation

Answer: (a) Initiation of DNA replication

Explanation: The origin of replication, abbreviated ori, is the DNA region at which replication can begin. It allows a plasmid to be copied within a compatible host. Its sequence and regulatory context influence plasmid copy number and host range.

Q132. Which selectable marker is often placed in laboratory plasmids?

[UPSC CSE — Practice]

(a) Insulin receptor
(b) Haemoglobin subunit
(c) Starch granule
(d) Antibiotic-resistance gene

Answer: (d) Antibiotic-resistance gene

Explanation: An antibiotic-resistance marker allows researchers to identify bacterial cells that carry a plasmid by growing them under controlled selection. Modern biotechnology also uses alternative selection systems. Laboratory marker use does not imply that antibiotic resistance is desirable in released organisms.

Q131. The term “sticky ends” refers to DNA fragments having:

[WBCS — Practice]

(a) No nucleotide bases
(b) Protein-coated circular ends
(c) Short single-stranded complementary overhangs
(d) An RNA cap at both ends

Answer: (c) Short single-stranded complementary overhangs

Explanation: Certain restriction enzymes generate staggered cuts, leaving short single-stranded overhangs called sticky ends. Complementary overhangs can pair transiently and facilitate ligation. Other restriction enzymes generate blunt-ended fragments that can also be joined using suitable methods.

Q130. Membrane bioreactors are chiefly associated with which biotechnological application?

[UPSC CSE (Pre) 2024]

(a) Drug delivery nanoparticles
(b) Wastewater treatment
(c) Vaccine inoculation
(d) Embryo transfer

Answer: (b) Wastewater treatment

Explanation: A membrane bioreactor combines microbial biodegradation with filtration through a membrane. It treats sewage and other wastewater while retaining suspended solids and many microorganisms. Ordinary fermentation bioreactors have broader uses, but membrane bioreactors chiefly denote wastewater-treatment systems.

Q129. In a recombinant plasmid, the foreign DNA sequence is commonly called the:

[MPPSC — Practice]

(a) Insert
(b) Centromere
(c) Ribosome
(d) Cell membrane

Answer: (a) Insert

Explanation: The inserted DNA fragment is referred to as an insert, while the receiving DNA molecule is the vector backbone. The combination forms a recombinant construct. Confirming insert orientation and sequence is important before downstream gene-expression experiments.

Q128. Which microbial process involves uptake of free DNA from the surrounding environment?

[UPPCS — Practice]

(a) Transcription
(b) Translation
(c) Respiration
(d) Transformation

Answer: (d) Transformation

Explanation: Transformation occurs when a competent cell takes up DNA from its environment. Natural transformation happens in some bacteria, while laboratory procedures can induce competence artificially. Researchers use transformation to introduce recombinant plasmids for cloning or protein production.

Q127. Which technique introduces DNA into cells using short high-voltage electrical pulses?

[RAS / RPSC — Practice]

(a) Dialysis
(b) Autoclaving
(c) Electroporation
(d) Filtration

Answer: (c) Electroporation

Explanation: Electroporation briefly alters cell-membrane permeability through electrical pulses, enabling nucleic acids or other molecules to enter. It is used with bacteria and some eukaryotic cells. Cell viability and delivery efficiency depend on voltage, buffer and cell type.

Q126. What is the primary purpose of downstream processing in recombinant protein production?

[SSC CGL — Practice]

(a) To select genes before cloning
(b) To purify and formulate the required product
(c) To destroy all cultured cells without recovering proteins
(d) To sequence every genome in the environment

Answer: (b) To purify and formulate the required product

Explanation: After a recombinant protein is expressed, downstream processing separates it from cells, culture medium and impurities. Steps can involve filtration, chromatography and formulation. Purity, activity, sterility and stability are particularly important for medical products.

Q125. In genetic studies, microsatellite DNA is particularly useful for which purpose?

[UPSC CSE (Pre) 2023]

(a) Comparing evolutionary relationships among animals
(b) Testing drug effectiveness across patients
(c) Turning stem cells into tissues
(d) Clonal multiplication of fruit plants

Answer: (a) Comparing evolutionary relationships among animals

Explanation: Microsatellites are short tandem-repeat regions whose repeat numbers vary between individuals and populations. This variability supplies genetic markers for population studies, parentage analysis and evolutionary comparisons. Their standard use is not cell differentiation, tissue culture or clinical drug trials.

Q124. Which plant-associated bacterium supplies a widely used gene-transfer system for plants?

[SSC CHSL — Practice]

(a) Mycobacterium leprae
(b) Vibrio cholerae
(c) Salmonella Typhi
(d) Agrobacterium tumefaciens

Answer: (d) Agrobacterium tumefaciens

Explanation: Agrobacterium tumefaciens naturally transfers part of its Ti plasmid into plant cells, causing crown-gall disease. Scientists modify the system by removing disease-causing regions and introducing selected genes. It is therefore an important vector for plant transformation.

Q123. In plant genetic engineering, the term T-DNA refers to:

[SSC MTS — Practice]

(a) A plant-specific amino acid
(b) Only mitochondrial DNA
(c) The portion of Ti plasmid DNA transferred into plant cells
(d) Every transfer RNA molecule

Answer: (c) The portion of Ti plasmid DNA transferred into plant cells

Explanation: T-DNA is the transferred segment of the Agrobacterium Ti plasmid. In engineered systems it can carry selected genes into a plant genome. Border sequences help define the region delivered from the bacterium to the recipient plant.

Q122. What is the principal objective of the polymerase chain reaction (PCR)?

[RRB NTPC — Practice]

(a) Translate proteins in a cell
(b) Rapidly amplify a defined DNA region
(c) Count red blood cells
(d) Separate fats from milk

Answer: (b) Rapidly amplify a defined DNA region

Explanation: PCR repeatedly denatures DNA, anneals primers and extends new strands, producing many copies of a selected region. A thermostable DNA polymerase makes repeated heating possible. PCR supports diagnostics, forensics, cloning and genetic research.

Q121. What does the expression “aerial metagenomics” most directly describe?

[UPSC CSE (Pre) 2023]

(a) Sampling DNA carried in environmental air
(b) Taking blood samples using airborne drones
(c) Collecting soil specimens through aircraft
(d) Sequencing only the genes of birds

Answer: (a) Sampling DNA carried in environmental air

Explanation: Aerial metagenomics examines genetic material captured from airborne biological particles, including microbial cells, spores and environmental DNA. By analysing material collected in air filters, researchers can study biodiversity without directly sampling every organism present in the habitat.

Q120. Taq polymerase was originally isolated from which organism?

[RRB Group D — Practice]

(a) Bacillus anthracis
(b) Escherichia coli
(c) Saccharomyces cerevisiae
(d) Thermus aquaticus

Answer: (d) Thermus aquaticus

Explanation: Taq DNA polymerase comes from the heat-tolerant bacterium Thermus aquaticus. Its thermostability helps it survive the high-temperature DNA-denaturation stages of PCR. This property made automated thermal cycling far more practical than when fresh polymerase had to be added repeatedly.

Q119. During the denaturation step of standard PCR, double-stranded DNA is:

[CGPSC — Practice]

(a) Broken into free amino acids
(b) Converted into proteins
(c) Separated into single strands by heating
(d) Linked to membrane receptors

Answer: (c) Separated into single strands by heating

Explanation: Heating disrupts hydrogen bonds between complementary bases and separates DNA strands. The next cooling step allows short primers to attach, and polymerase then extends those primers. Repetition of these stages amplifies the target sequence.

Q118. What determines the approximate starting and ending positions of a PCR amplicon?

[UPSC CDS — Practice]

(a) The concentration of haemoglobin
(b) Sequence-specific primers
(c) Only the size of the test tube
(d) The colour of DNA

Answer: (b) Sequence-specific primers

Explanation: A forward and reverse primer bind opposite strands on either side of the desired region. Their positions define the amplified segment. Primer sequence and annealing conditions affect specificity, while reaction chemistry affects yield and reliability.

Q117. DNA barcoding can help:
1. determine the exact age of an animal;
2. separate visually similar species;
3. identify undeclared species in processed foods.

Which are valid uses?

[UPSC CSE (Pre) 2022]

(a) 2 and 3
(b) 3 only
(c) 1 only
(d) 1 and 2

Answer: (a) 2 and 3

Explanation: DNA barcoding reads standard genetic markers to identify the species from which a sample originated. It can detect look-alike species and food adulteration. Standard DNA barcodes do not reveal the age of a particular plant or animal.

Q116. Which laboratory method separates DNA fragments mainly by their migration through a gel in an electric field?

[UPSC NDA — Practice]

(a) Titration
(b) Distillation
(c) Centrifugal chromatography only
(d) Gel electrophoresis

Answer: (d) Gel electrophoresis

Explanation: DNA carries a negatively charged phosphate backbone and migrates toward the positive electrode during electrophoresis. In an appropriate gel matrix, smaller fragments generally travel farther than larger ones. The method supports DNA sizing and checking PCR products.

Q115. In typical agarose electrophoresis, DNA migrates towards the:

[State PSC — Practice]

(a) Centre of the gel regardless of charge
(b) Cathode or negative terminal
(c) Anode or positive terminal
(d) Nearest light source

Answer: (c) Anode or positive terminal

Explanation: The phosphate groups of DNA confer an overall negative charge. Under an electric field DNA moves toward the positively charged electrode, the anode. Migration distance varies with fragment size, gel concentration and running conditions.

Q114. Which technique reads the order of nucleotides in a DNA sample?

[UPSC CSE — Practice]

(a) Dialysis
(b) DNA sequencing
(c) Protein precipitation
(d) Osmosis

Answer: (b) DNA sequencing

Explanation: DNA sequencing determines the order of bases in a DNA molecule. Sanger sequencing and high-throughput sequencing use different detection strategies. Sequence data help identify variants, analyse pathogens and map genes across whole genomes.

Q113. In vaccine-platform terminology, which pair is accurate: 1. Covishield uses an mRNA vaccine platform; 2. Sputnik V uses a viral vector; 3. Covaxin contains inactivated virus?

[UPSC CSE (Pre) 2022]

(a) 2 and 3 only
(b) 1 and 3 only
(c) All three
(d) 1 and 2 only

Answer: (a) 2 and 3 only

Explanation: Covishield and Sputnik V both employ adenoviral vector approaches, whereas Covaxin uses inactivated SARS-CoV-2. Messenger-RNA vaccines constitute another platform. Thus the claim assigning an mRNA platform to Covishield is incorrect; the other two descriptions are accurate.

Q112. A genomic library normally contains:

[WBCS — Practice]

(a) Only messenger RNA molecules
(b) Every mineral in a cell
(c) Only circulating blood proteins
(d) DNA fragments representing an organism’s genome

Answer: (d) DNA fragments representing an organism’s genome

Explanation: A genomic library is a collection of cloned genomic DNA fragments. With adequate coverage, the inserts collectively represent the genome, including coding and noncoding regions. Libraries may be stored in plasmid, phage or artificial-chromosome vectors.

Q111. A complementary DNA (cDNA) library differs from a genomic library because it is derived from:

[MPPSC — Practice]

(a) All intergenic DNA exclusively
(b) Mineral salts
(c) Mature RNA transcripts
(d) Cellular membranes

Answer: (c) Mature RNA transcripts

Explanation: A cDNA library is produced by reverse-transcribing RNA, commonly mature messenger RNA, into DNA and cloning it. It chiefly reflects genes expressed in the sampled tissue or condition rather than the entire genomic sequence with introns and intergenic regions.

Q110. Which enzyme creates DNA using RNA as its template?

[UPPCS — Practice]

(a) Restriction enzyme
(b) Reverse transcriptase
(c) DNA ligase
(d) Lipase

Answer: (b) Reverse transcriptase

Explanation: Reverse transcriptase copies RNA into complementary DNA. It is naturally associated with retroviruses and is widely employed in molecular diagnostics and cDNA synthesis. Researchers often combine reverse transcription with PCR when measuring RNA expression.

Q109. Consider recombinant-vector vaccines:
1. Genetic engineering is used in their design.
2. Certain viruses and bacteria serve as gene-delivery vectors.

Which statements are correct?

[UPSC CSE (Pre) 2021]

(a) Both 1 and 2
(b) 1 only
(c) Neither statement
(d) 2 only

Answer: (a) Both 1 and 2

Explanation: Recombinant-vector vaccines employ a modified virus or bacterium to carry genetic instructions for producing an antigen. Creating that construct requires recombinant DNA methods. Depending on the vector and antigen, these vaccines can stimulate antibody and cellular immune responses.

Q108. What does the term “metagenomics” most closely mean?

[RAS / RPSC — Practice]

(a) Examining only one pure bacterial isolate
(b) Measuring atmospheric temperature
(c) Counting chromosomes through a microscope
(d) Studying genetic material recovered directly from mixed environmental communities

Answer: (d) Studying genetic material recovered directly from mixed environmental communities

Explanation: Metagenomics analyses DNA or other genetic information from mixtures of organisms in environmental or clinical samples. It can reveal microbes that are difficult to culture, describe community diversity and identify metabolic capabilities from sequence data.

Q107. The Cas9 protein functions mainly as a:

[SSC CGL — Practice]

(a) Plant hormone
(b) Starch storage molecule
(c) RNA-guided DNA-cutting enzyme
(d) Structural protein of haemoglobin

Answer: (c) RNA-guided DNA-cutting enzyme

Explanation: Cas9 is a nuclease that makes DNA breaks at target sequences specified by guide RNA, subject to suitable PAM recognition. Cellular repair pathways then create the final editing outcome. It is one of several enzymes used in CRISPR-based systems.

Q106. What provides target-sequence recognition in standard CRISPR-Cas9 editing?

[SSC CHSL — Practice]

(a) Ribosomal protein alone
(b) Guide RNA
(c) Insulin hormone
(d) Chlorophyll

Answer: (b) Guide RNA

Explanation: A guide RNA contains a segment complementary to a chosen DNA target and directs Cas9 there. The enzyme also requires an appropriate PAM near the target. Changing the guide sequence can redirect the system to different genomic sites.

Q105. Which statements about mitochondrial replacement therapy are correct?
1. It may be performed before or after fertilisation.
2. Mitochondrial DNA is ordinarily transmitted maternally.

[UPSC CSE (Pre) 2021]

(a) Both 1 and 2
(b) 2 only
(c) Neither 1 nor 2
(d) 1 only

Answer: (a) Both 1 and 2

Explanation: Maternal spindle transfer occurs before fertilisation, whereas pronuclear transfer occurs after fertilisation. Both seek to reduce transmission of harmful maternal mitochondrial variants. Mitochondria in the human embryo are inherited overwhelmingly from the egg, making both statements correct.

Q104. The expansion of CRISPR includes which phrase?

[SSC MTS — Practice]

(a) Chromosomal Repair in Special Prokaryotes
(b) Central RNA-Integrated Protein Repair System
(c) Circular Repeated Information Sequence Process
(d) Clustered Regularly Interspaced Short Palindromic Repeats

Answer: (d) Clustered Regularly Interspaced Short Palindromic Repeats

Explanation: CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. These repeated DNA elements were first studied within microbial defence systems. Engineered CRISPR systems now provide tools for changing, regulating and detecting nucleic-acid sequences.

Q103. An “off-target effect” in genome editing occurs when:

[RRB NTPC — Practice]

(a) A plant grows toward sunlight
(b) PCR is performed at the target temperature
(c) The editing machinery alters an unintended DNA location
(d) A gene undergoes normal transcription

Answer: (c) The editing machinery alters an unintended DNA location

Explanation: Off-target editing means a nuclease or editing system modifies a sequence other than the intended target. Similar DNA sequences can sometimes be recognised inadvertently. Careful guide design and independent validation reduce, but may not completely eliminate, this risk.

Q102. Compared with a conventional Cas9 double-strand break, a base editor is designed primarily to:

[RRB Group D — Practice]

(a) Duplicate every chromosome
(b) Change selected bases without necessarily cutting both DNA strands
(c) Destroy all cellular RNA
(d) Remove the cell nucleus

Answer: (b) Change selected bases without necessarily cutting both DNA strands

Explanation: Base editing couples a targeting protein with a chemical editing activity that can convert particular bases. Many designs avoid deliberate double-strand breaks. Editing windows, bystander changes and off-target activity nevertheless require careful assessment.

Q101. The names Bollgard I and Bollgard II refer primarily to genetically modified varieties of which crop?

[UPSC CSE (Pre) 2021]

(a) Cotton
(b) Mustard
(c) Rice
(d) Wheat

Answer: (a) Cotton

Explanation: Bollgard technologies are associated with insect-resistant Bt cotton. Bollgard I used a Cry toxin gene, while Bollgard II added another Cry gene to broaden protection against certain bollworms. The introduced proteins originated from Bacillus thuringiensis.

Q100. Prime editing is distinguished by its use of:

[CGPSC — Practice]

(a) Radioactive fusion of cells
(b) A microscope with infrared filters
(c) A bacterial ribosome only
(d) A Cas-derived targeting system and reverse-transcriptase activity

Answer: (d) A Cas-derived targeting system and reverse-transcriptase activity

Explanation: Prime editing employs a specialised guide RNA and an engineered Cas protein linked to reverse transcriptase. It can specify various small substitutions, insertions and deletions. Actual editing efficiency and precision depend strongly on cellular and target characteristics.

Q99. Which type of mutation is most directly associated with the insertion or deletion of bases not divisible by three in a coding sequence?

[UPSC CDS — Practice]

(a) Normal recombination
(b) Balanced translocation only
(c) Frameshift mutation
(d) Silent substitution

Answer: (c) Frameshift mutation

Explanation: Insertions or deletions that change the reading frame alter downstream codon grouping in a protein-coding sequence. This may produce an abnormal protein or early stop codon. Insertions in multiples of three can preserve the frame while adding amino acids.

Q98. Gene silencing by small interfering RNA primarily targets which molecule?

[UPSC NDA — Practice]

(a) Cholesterol
(b) Messenger RNA
(c) Cellulose
(d) ATP synthase protein exclusively

Answer: (b) Messenger RNA

Explanation: Small interfering RNA associates with protein complexes that recognise complementary messenger RNA. The target RNA is cleaved or functionally suppressed, reducing production of the corresponding protein. Gene silencing can therefore change expression without editing the DNA sequence.

Q97. Which uses of present-day biotechnology are scientifically possible?
1. Genetic modification of sperm- or egg-forming cells.
2. Editing an early human embryo.
3. Introducing human induced pluripotent stem cells into animal embryos.

[UPSC CSE (Pre) 2020]

(a) 1, 2 and 3
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1 only

Answer: (a) 1, 2 and 3

Explanation: All three procedures have been explored scientifically, though their clinical and research uses face major ethical, safety and legal restrictions. Technical feasibility does not imply unrestricted permission. Germline modification is especially sensitive because heritable alterations could pass to future generations.

Q96. In genetic engineering, a promoter is needed chiefly to:

[State PSC — Practice]

(a) Provide all amino acids
(b) Stop DNA replication permanently
(c) Digest cell walls
(d) Initiate transcription of a downstream gene

Answer: (d) Initiate transcription of a downstream gene

Explanation: Promoters are DNA regulatory regions recognised by transcription machinery. Their position and sequence help determine when and how strongly a gene is transcribed. Expression vectors often place a promoter before the inserted coding sequence.

Q95. A reporter gene such as GFP is included in experiments largely to:

[UPSC CSE — Practice]

(a) Replace every housekeeping gene
(b) Cause universal pest resistance
(c) Make gene expression or cell location observable
(d) Produce vitamin A in all tissues

Answer: (c) Make gene expression or cell location observable

Explanation: Green fluorescent protein and other reporter products generate detectable signals. They help researchers track promoter activity, protein localisation and transformed cells. A reporter is an experimental readout rather than a guaranteed method for improving an organism.

Q94. What was the central objective of the Human Genome Project?

[WBCS — Practice]

(a) Identify only blood-group alleles
(b) Determine a reference sequence and map of the human genome
(c) Create a genetically identical human population
(d) Manufacture all human vaccines

Answer: (b) Determine a reference sequence and map of the human genome

Explanation: The Human Genome Project sought to map and sequence the human genetic blueprint and develop public genomic resources. Begun in 1990, its major project phase concluded in 2003. It laid foundations for variant discovery, genomics and precision medicine.

Q93. In an older biotechnology MCQ, which claim was officially treated as the incorrect one?

[UPSC CSE (Pre) 2019]

(a) Joining DNA from different species readily creates a functional chromosome
(b) Artificial functional DNA segments can be synthesised
(c) Plant and animal cells can divide in laboratory cultures
(d) DNA can be copied outside living cells

Answer: (a) Joining DNA from different species readily creates a functional chromosome

Explanation: The official UPSC key selected the first claim. However, modern artificial-chromosome systems make its categorical wording debatable. DNA synthesis, cell-free amplification and cell culture are established techniques. For revision, distinguish the historical official key from current technical nuance.

Q92. Approximately how many protein-coding genes are recognised in the human genome?

[MPPSC — Practice]

(a) About 2 million
(b) About 200
(c) About 2,000
(d) About 20,000

Answer: (d) About 20,000

Explanation: Modern annotations recognise roughly twenty thousand human protein-coding genes, with estimates varying slightly across databases. Older textbooks sometimes quoted thirty thousand or more. Much of the genome also includes noncoding sequences involved in regulation, chromosome structure and other functions.

Q91. Bioinformatics is best described as the application of which discipline to biological data?

[UPPCS — Practice]

(a) Civil-engineering concrete tests
(b) Road surveying
(c) Computational and statistical methods
(d) Only classical mechanics

Answer: (c) Computational and statistical methods

Explanation: Bioinformatics combines biology, computing, mathematics and statistics to manage and interpret biological datasets. It supports sequence alignment, genome annotation, protein modelling and evolutionary comparison. The field is essential because modern sequencing produces data at large scale.

Q90. What is the central purpose of genome annotation?

[RAS / RPSC — Practice]

(a) Convert every gene to protein in vitro
(b) Identify and describe genes and other functional sequence features
(c) Remove all noncoding DNA
(d) Replace chromosomal centromeres

Answer: (b) Identify and describe genes and other functional sequence features

Explanation: Genome annotation assigns biological information to DNA sequences, including gene boundaries, coding regions, RNA genes and regulatory features. Automated predictions are improved by experimental evidence. Annotation turns a sequence assembly into a resource that scientists can interpret.

Q89. Cas9, frequently mentioned alongside CRISPR, is best described as which of the following?

[UPSC CSE (Pre) 2019]

(a) A DNA-cutting endonuclease guided by RNA
(b) A protein that translates messenger RNA
(c) An antibody against bacterial toxins
(d) A hormone derived from yeast

Answer: (a) A DNA-cutting endonuclease guided by RNA

Explanation: Cas9 is an RNA-guided nuclease that cleaves DNA at a chosen target adjacent to a compatible PAM. CRISPR guide RNA provides sequence specificity. Its molecular-scissor action enables precise gene editing, though repair outcomes require experimental control.

Q88. Genome-wide association studies usually seek associations between:

[SSC CGL — Practice]

(a) Cell size and optical wavelength only
(b) Rainfall and rock hardness
(c) Blood pressure and latitude alone
(d) Genetic variants and measured traits or diseases

Answer: (d) Genetic variants and measured traits or diseases

Explanation: Genome-wide association studies test many genetic variants across a population to locate statistically associated regions. These associations may highlight biological pathways, but an associated variant is not automatically causal. Population structure and multiple testing require careful adjustment.

Q87. What is a single-nucleotide polymorphism (SNP)?

[SSC CHSL — Practice]

(a) Exchange of a complete organ
(b) Deletion of an entire species
(c) A common variation at one nucleotide position
(d) An enzyme that joins DNA fragments

Answer: (c) A common variation at one nucleotide position

Explanation: An SNP is a sequence variant at a single genomic position occurring at appreciable frequency in a population. SNPs are useful markers for mapping traits, investigating ancestry and studying disease susceptibility. Most SNPs are not directly harmful.

Q86. In sequence comparison, homology means that genes or sequences:

[SSC MTS — Practice]

(a) Have equal length with no exceptions
(b) Share a common evolutionary ancestry
(c) Occur only in plants
(d) Always perform the same biochemical function

Answer: (b) Share a common evolutionary ancestry

Explanation: Homologous sequences descend from a common ancestral sequence. Their similarity may indicate related functions, but functions can diverge after duplication or speciation. Homology is an evolutionary relationship, not simply a numerical percentage of sequence identity.

Q85. RNA interference (RNAi) technology suppresses gene expression principally through which mechanism?

[UPSC CSE (Pre) 2019]

(a) Silencing complementary RNA molecules
(b) Forming new ribosomes
(c) Increasing DNA methylation in every gene
(d) Amplifying target chromosomes

Answer: (a) Silencing complementary RNA molecules

Explanation: RNA interference uses short RNA molecules to guide protein complexes towards complementary messenger RNA. The targeted RNA is degraded or its translation blocked. This reduces expression of a selected gene without necessarily changing the underlying DNA sequence.

Q84. Which technique is chiefly used to compare thousands of gene-expression measurements simultaneously?

[RRB NTPC — Practice]

(a) Gravimetric ash testing
(b) Simple hand lens inspection
(c) Rain gauge measurement
(d) Expression microarray or RNA sequencing

Answer: (d) Expression microarray or RNA sequencing

Explanation: Microarrays and RNA sequencing measure expression across many genes within a sample. Researchers compare expression patterns among tissues or treatments to identify biological responses. RNA sequencing additionally detects transcripts without requiring every transcript to have a predesigned probe.

Q83. An organism’s complete protein complement under specified conditions is called its:

[RRB Group D — Practice]

(a) Plasmidome only
(b) Karyotype
(c) Proteome
(d) Cytoskeleton

Answer: (c) Proteome

Explanation: The proteome includes proteins expressed in a cell, tissue or organism under defined conditions. Unlike a relatively stable genomic sequence, protein abundance and modification can change rapidly. Proteomics investigates these molecules, often using mass spectrometry.

Q82. The main target of Bt cotton technology is resistance against:

[CGPSC — Practice]

(a) All bacterial diseases
(b) Certain insect pests, including bollworms
(c) Every weed species
(d) Drought in all conditions

Answer: (b) Certain insect pests, including bollworms

Explanation: Bt cotton expresses selected insecticidal Cry proteins from Bacillus thuringiensis. These proteins affect particular susceptible insects, including important bollworm pests. They do not confer universal resistance to all insects, diseases or environmental stresses.

Q81. DNA fingerprinting depends most fundamentally upon which feature?

[RAS / RPSC (Pre) 2018]

(a) Genetic polymorphism
(b) Constant chromosome length
(c) Identical mitochondrial genomes
(d) Uniform DNA sequences

Answer: (a) Genetic polymorphism

Explanation: DNA polymorphism denotes heritable sequence differences among individuals. Variation in short tandem repeats and other markers forms distinguishing DNA profiles. Since profiles are inherited, the same data can help resolve biological relationships as well as forensic identity.

Q80. Which biological source provides the cry genes widely used in insect-resistant crops?

[UPSC CDS — Practice]

(a) Lactobacillus acidophilus
(b) Rhizobium leguminosarum
(c) Plasmodium vivax
(d) Bacillus thuringiensis

Answer: (d) Bacillus thuringiensis

Explanation: Bacillus thuringiensis is a soil bacterium that produces a range of insecticidal Cry proteins. Scientists can transfer suitable cry genes into plants to obtain resistance to target insects. Different Cry proteins vary in their insect specificity.

Q79. The insecticidal activity of many Bt Cry proteins is associated with:

[UPSC NDA — Practice]

(a) Blocking plant photosynthesis
(b) Destroying all soil fungi
(c) Damage to susceptible insect gut cells
(d) Inducing chlorophyll loss in rice

Answer: (c) Damage to susceptible insect gut cells

Explanation: In susceptible insects, activated Cry proteins interact with midgut structures and disrupt epithelial cell integrity, causing lethal damage. Toxicity depends on the specific protein and insect. Resistance management is needed because pest populations may evolve reduced susceptibility.

Q78. Golden Rice gains its yellow-orange appearance mainly from accumulation of:

[State PSC — Practice]

(a) Haemoglobin
(b) Beta-carotene
(c) Anthocyanin
(d) Melanin

Answer: (b) Beta-carotene

Explanation: Golden Rice has been engineered to synthesise carotenoids in the normally pale endosperm. Beta-carotene gives the grain a golden appearance and can serve as a vitamin A precursor. Its nutrient content can vary with variety and storage conditions.

Q77. In the pair “CRISPR–Cas9 — particle physics”, what is wrong?

[UPSC CSE (Pre) 2018]

(a) CRISPR–Cas9 is actually a genome-editing technology
(b) No RNA is involved in CRISPR
(c) CRISPR stands for an Indian satellite
(d) Cas9 is an astronomical instrument

Answer: (a) CRISPR–Cas9 is actually a genome-editing technology

Explanation: CRISPR–Cas9 belongs to genetic engineering, not particle physics. A guide RNA directs the Cas9 protein to a complementary DNA target for cutting. Its discovery advanced biotechnology, plant improvement and biomedical research, although off-target modifications remain a concern.

Q76. Flavr Savr tomato was engineered primarily to alter which process?

[UPSC CSE — Practice]

(a) Nitrogen fixation in roots
(b) Synthesis of human insulin
(c) Chlorophyll production in seeds
(d) Fruit softening related to polygalacturonase

Answer: (d) Fruit softening related to polygalacturonase

Explanation: Flavr Savr used antisense technology to reduce expression of a polygalacturonase enzyme involved in cell-wall breakdown. It was designed to delay softening of tomatoes. The product became the first commercially marketed genetically engineered whole food in 1994.

Q75. What is antisense RNA designed to do in a gene-regulation experiment?

[WBCS — Practice]

(a) Destroy every ribosome in the cell
(b) Replicate independently as a chromosome
(c) Bind a complementary RNA and interfere with its expression
(d) Convert an amino acid to a nucleotide

Answer: (c) Bind a complementary RNA and interfere with its expression

Explanation: An antisense RNA is complementary to a chosen RNA sequence. Base pairing can interfere with translation, RNA processing or RNA stability. Antisense approaches demonstrated that gene expression could be suppressed without directly deleting the gene.

Q74. Which genetically modified crop was approved for commercial cultivation in India in 2002?

[MPPSC — Practice]

(a) Flavr Savr tomato
(b) Bt cotton
(c) GM wheat
(d) Golden Rice

Answer: (b) Bt cotton

Explanation: Bt cotton received commercial cultivation approval in India in 2002. It became a major example in discussions of agricultural biotechnology, resistance management and biosafety. Approval of one crop does not imply approval of all genetically engineered crops.

Q73. Choose correct statements about environmental bioremediation:
1. It enhances natural microbial degradation.
2. All heavy metals can be completely degraded biologically.
3. Engineered microbes may be used.

[UPSC CSE (Pre) 2017]

(a) 1 and 3 only
(b) 1, 2 and 3
(c) 2 and 3 only
(d) 1 only

Answer: (a) 1 and 3 only

Explanation: Microorganisms can metabolise many organic pollutants, and genetic engineering may improve these pathways. Heavy metals are elements; they cannot be biodegraded into non-elements. Microbes may instead transform, immobilise or accumulate metals. Therefore statements one and three are valid.

Q72. The purpose of an insect-resistance refuge strategy around Bt crops is primarily to:

[UPPCS — Practice]

(a) Increase pesticide use automatically
(b) Prevent root formation
(c) Make crops sterile
(d) Slow selection for Bt-resistant pest populations

Answer: (d) Slow selection for Bt-resistant pest populations

Explanation: Refuge areas maintain susceptible insects that can mate with individuals surviving Bt exposure. This can delay the spread of resistance genes under suitable biological conditions. Effective resistance management also depends on toxin expression and pest biology.

Q71. Which property is targeted by engineering salt-tolerant crop varieties?

[RAS / RPSC — Practice]

(a) Production of red blood cells
(b) Formation of animal antibodies
(c) Tolerance of saline growing conditions
(d) Absence of all stomata

Answer: (c) Tolerance of saline growing conditions

Explanation: Salinity-tolerance engineering explores ion transport, osmotic adjustment, stress signalling and protective metabolites. These pathways can help plants maintain growth when soils contain excess salts. A single genetic modification rarely solves every environmental limitation affecting yields.

Q70. Biofortification is best defined as:

[SSC CGL — Practice]

(a) Changing only packaging colour
(b) Improving the nutritional content of crops
(c) Removing all minerals from grain
(d) Sterilising crop seeds with heat

Answer: (b) Improving the nutritional content of crops

Explanation: Biofortification seeks to increase useful nutrients in edible crop portions through conventional breeding, agronomic methods or biotechnology. Examples include provitamin A, iron and zinc enhancement. It complements, rather than replaces, diverse diets and public-health interventions.

Q69. How can sequencing crop genomes help agriculture?
1. Locate disease- and drought-resistance markers.
2. Accelerate breeding programmes.
3. Study crop–pathogen interactions.

[UPSC CSE (Pre) 2017]

(a) All three
(b) 1 and 3 only
(c) 2 and 3 only
(d) 1 only

Answer: (a) All three

Explanation: Sequencing reveals genetic markers linked with useful crop traits. Breeders use those markers to select desirable plants earlier, while comparative genomic studies clarify interactions between hosts and pathogens. All three stated applications are supported by contemporary crop genetics.

Q68. Marker-assisted selection improves crop breeding through use of:

[SSC CHSL — Practice]

(a) Random chemical fertilisers only
(b) Animal cloning alone
(c) Vaccine antigens
(d) DNA markers linked to desirable traits

Answer: (d) DNA markers linked to desirable traits

Explanation: Marker-assisted selection tracks DNA variants associated with traits such as disease resistance. Breeders can select promising plants before the trait becomes visible. Unlike transgenic engineering, marker-assisted selection need not introduce foreign genes into crop genomes.

Q67. What does a transgenic plant contain by definition?

[SSC MTS — Practice]

(a) Only mitochondria inherited from pollen
(b) No DNA at all
(c) A genetic construct introduced by genetic engineering
(d) Exactly twice the normal number of genes

Answer: (c) A genetic construct introduced by genetic engineering

Explanation: A transgenic plant contains an introduced genetic sequence integrated or maintained through genetic engineering. The introduced sequence may come from another species or be modified from the same species. Transgenesis differs from ordinary cross-pollination and marker-assisted selection.

Q66. Why is recombinant human insulin preferable to some older animal-derived preparations?

[RRB NTPC — Practice]

(a) It requires no purification
(b) It matches the human insulin sequence and can be produced consistently
(c) It cures every type of diabetes permanently
(d) It is an antibiotic

Answer: (b) It matches the human insulin sequence and can be produced consistently

Explanation: Recombinant expression systems manufacture insulin with the human amino-acid sequence. This enabled scalable, controlled production and reduced reliance on animal pancreases. Insulin replacement treats diabetes but does not usually correct its underlying biological causes.

Q65. A bacteriophage can be used in genetic engineering because it:
1. infects bacteria;
2. can carry genetic material into bacterial cells.

[UP RO/ARO (Pre) 2017]

(a) Both 1 and 2
(b) 2 only
(c) Neither
(d) 1 only

Answer: (a) Both 1 and 2

Explanation: Bacteriophages are viruses specialised for infection of bacteria. Their ability to deliver nucleic acids makes certain phages useful as cloning vectors and in molecular genetics. Both statements reflect their natural biology and practical use in laboratories.

Q64. Which microorganism is often engineered to produce therapeutic human proteins?

[RRB Group D — Practice]

(a) Ascaris lumbricoides
(b) Plasmodium falciparum
(c) Taenia solium
(d) Escherichia coli

Answer: (d) Escherichia coli

Explanation: Escherichia coli is a well-characterised bacterium widely used to express recombinant proteins, including some insulin products. Yeast and mammalian cells are alternatives when protein folding or post-translational processing demands different biological machinery.

Q63. Which human disorder is a classic textbook target for gene therapy using corrected lymphocytes?

[CGPSC — Practice]

(a) Scurvy
(b) Simple dehydration
(c) Adenosine deaminase deficiency
(d) Night blindness caused solely by diet

Answer: (c) Adenosine deaminase deficiency

Explanation: Certain severe combined immunodeficiency cases result from deficiency of adenosine deaminase. Ex vivo gene therapy can introduce a functional ADA gene into patient cells. This example illustrates replacement of a missing enzyme through a therapeutic genetic construct.

Q62. Ex vivo gene therapy involves which sequence?

[UPSC CDS — Practice]

(a) Edit only food products
(b) Remove patient cells, modify them outside the body and return them
(c) Replace all chromosomes with proteins
(d) Transfer sperm nuclei into eggs

Answer: (b) Remove patient cells, modify them outside the body and return them

Explanation: In ex vivo gene therapy, cells are collected, genetically modified under controlled conditions and reinfused into the patient. This permits quality testing before administration. The approach is used for selected blood and immune-cell therapies.

Q61. A permanent change in the nucleotide sequence of a gene is termed what?

[UPPCS (Pre) 2016]

(a) Mutation
(b) Hybridisation
(c) Fertilisation
(d) Cloning

Answer: (a) Mutation

Explanation: A mutation alters DNA nucleotide sequence through substitution, insertion, deletion or another change. Some mutations affect protein function or gene regulation, while others are silent. Cloning copies genetic material; it does not inherently describe a sequence alteration.

Q60. In vivo gene therapy differs from ex vivo therapy because genetic material is:

[UPSC NDA — Practice]

(a) Only used in dead cells
(b) Never carried by vectors
(c) Always transferred into plants
(d) Delivered directly into the patient’s tissues

Answer: (d) Delivered directly into the patient’s tissues

Explanation: In vivo therapy delivers genetic material or editing machinery directly into the body, using methods such as viral vectors or nanoparticles. Ex vivo therapy modifies collected cells before returning them. Each approach has distinct challenges of targeting and safety.

Q59. Which cells are modified in standard CAR-T cell therapy?

[State PSC — Practice]

(a) Platelets
(b) Osteoclasts only
(c) T lymphocytes
(d) Mature red blood cells

Answer: (c) T lymphocytes

Explanation: Chimeric antigen receptor T-cell therapy engineers a patient’s or donor’s T lymphocytes to recognise selected cell-surface targets. It has transformed treatment of certain blood cancers. Potential adverse effects include cytokine-release syndrome and neurological complications.

Q58. Monoclonal antibodies are populations of antibodies that typically:

[UPSC CSE — Practice]

(a) Are produced only in plants
(b) Recognise the same specific epitope
(c) Have randomly unrelated binding sites
(d) Contain no protein

Answer: (b) Recognise the same specific epitope

Explanation: Monoclonal antibodies arise from a single antibody-producing cell lineage or engineered equivalent. They target a defined antigenic epitope and are used in diagnostics and medicine. Their specificity distinguishes them from broad mixtures of polyclonal antibodies.

Q57. The term transcriptome denotes which collection?

[UPSC CSE (Pre) 2016]

(a) All RNA transcripts expressed under specified conditions
(b) Every protein of an organism
(c) The entire set of chromosomes in mitosis
(d) The complete DNA sequence only

Answer: (a) All RNA transcripts expressed under specified conditions

Explanation: The transcriptome is the total collection of RNA transcripts expressed by a cell, tissue or organism in a defined condition. Unlike the genome, expression patterns can change with developmental stage, cell type, disease and environmental signals.

Q56. Hybridoma technology usually combines which two cell types?

[WBCS — Practice]

(a) Red blood cell and platelet
(b) Neuron and pollen grain
(c) Skin cell and chloroplast
(d) Antibody-producing B cell and immortal myeloma cell

Answer: (d) Antibody-producing B cell and immortal myeloma cell

Explanation: A hybridoma is formed by fusing a selected antibody-producing B lymphocyte with an immortal myeloma cell. The resulting clone can secrete a specific antibody continuously. This technology made large-scale monoclonal antibody production possible.

Q55. A recombinant subunit vaccine usually contains:

[MPPSC — Practice]

(a) A transplanted human chromosome
(b) Only an antibiotic
(c) A selected pathogen antigen produced by recombinant methods
(d) The complete infectious pathogen in every case

Answer: (c) A selected pathogen antigen produced by recombinant methods

Explanation: Recombinant subunit vaccines expose the immune system to selected antigens, often proteins produced in engineered cells. They do not necessarily contain live pathogens. Because isolated antigens may stimulate weaker responses, formulation and adjuvants are important.

Q54. Recombinant hepatitis B vaccine is produced using genetically engineered cells that express:

[UPPCS — Practice]

(a) Rabies virus genome in full
(b) Hepatitis B surface antigen
(c) Human haemoglobin
(d) Bacterial cellulose

Answer: (b) Hepatitis B surface antigen

Explanation: Many hepatitis B vaccines contain recombinant hepatitis B surface antigen made in expression hosts such as yeast. The purified antigen stimulates protective immunity without requiring live hepatitis B virus in the vaccine preparation.

Q53. Which structure is especially common as a vector in bacterial genetic engineering?

[UPPCS (Pre) 2015]

(a) Plasmid
(b) Lysosome
(c) Plastid
(d) Ribosome

Answer: (a) Plasmid

Explanation: Plasmids are small, generally circular extrachromosomal DNA molecules that can replicate independently in bacteria. Engineered plasmids carry origins of replication, selectable markers and insertion sites, allowing researchers to introduce and amplify genes within appropriate host cells.

Q52. Which genetic material is delivered by an mRNA vaccine to instruct cells to make an antigen?

[RAS / RPSC — Practice]

(a) Only a preformed antibody
(b) Purified starch
(c) An intact human chromosome
(d) Messenger RNA

Answer: (d) Messenger RNA

Explanation: Messenger-RNA vaccines introduce RNA instructions that host cells translate into an antigen. Lipid nanoparticles commonly protect and deliver the RNA. The mRNA does not need to enter the nucleus or alter chromosomal DNA to produce an immune response.

Q51. A viral vector differs from a naked DNA fragment because the vector:

[SSC CGL — Practice]

(a) Cannot enter any cell
(b) Contains no nucleic acid
(c) Uses engineered virus-associated delivery mechanisms
(d) Must always cause the original disease

Answer: (c) Uses engineered virus-associated delivery mechanisms

Explanation: Viral vectors exploit the ability of viruses to deliver nucleic acids into cells. Vectors are engineered to limit unwanted replication or pathology while carrying useful genetic instructions. Targeting, immune response and insertional risks depend on the chosen vector.

Q50. The two defining properties of a stem cell are:

[SSC CHSL — Practice]

(a) Production of haemoglobin and chlorophyll
(b) Self-renewal and capacity to differentiate
(c) Permanent inability to divide and no nucleus
(d) Formation of only cell walls

Answer: (b) Self-renewal and capacity to differentiate

Explanation: Stem cells can maintain their population through self-renewal and can give rise to specialised descendants. Their differentiation capacity varies: embryonic stem cells are pluripotent, whereas many adult stem cells are restricted to particular tissue lineages.

Q49. Who achieved landmark enzymatic synthesis of DNA outside living cells?

[BPSC (Pre) 2015]

(a) Arthur Kornberg
(b) Robert Hooke
(c) Edward Jenner
(d) Louis Pasteur

Answer: (a) Arthur Kornberg

Explanation: Arthur Kornberg isolated DNA polymerase and demonstrated enzymatic DNA synthesis in vitro. His research clarified mechanisms of DNA replication and earned a share of the 1959 Nobel Prize in Physiology or Medicine with Severo Ochoa.

Q48. Embryonic stem cells are traditionally isolated from which embryonic structure?

[SSC MTS — Practice]

(a) Adult skin epidermis
(b) Mature sperm tail
(c) Placental villus only
(d) Inner cell mass of the blastocyst

Answer: (d) Inner cell mass of the blastocyst

Explanation: Embryonic stem cells are classically derived from the inner cell mass of a preimplantation blastocyst. These cells can generate derivatives of the three embryonic germ layers. Their derivation and use raise important ethical and regulatory questions.

Q47. A pluripotent stem cell can produce:

[RRB NTPC — Practice]

(a) Only red blood cells
(b) An entire organism including all extraembryonic tissues in every setting
(c) Cell types derived from all three embryonic germ layers
(d) Only mature sperm cells

Answer: (c) Cell types derived from all three embryonic germ layers

Explanation: Pluripotency means the ability to differentiate into a broad range of cell types originating from ectoderm, mesoderm and endoderm. It differs from totipotency, which includes the capacity to generate extraembryonic supporting structures under suitable conditions.

Q46. Induced pluripotent stem cells are usually produced by:

[RRB Group D — Practice]

(a) Collecting only adult erythrocytes
(b) Reprogramming differentiated somatic cells
(c) Fusing two sperm cells
(d) Removing every gene from an embryo

Answer: (b) Reprogramming differentiated somatic cells

Explanation: Induced pluripotent stem cells are created by reprogramming differentiated cells using defined factors. They acquire properties resembling embryonic pluripotency. This approach supports disease modelling and drug testing while avoiding some issues linked to embryonic-cell derivation.

Q45. Apart from ordinary fingerprints, which characteristics can support biometric identification?
1. Iris patterns;
2. retinal patterns;
3. voice characteristics.

[UPSC CSE (Pre) 2014]

(a) 1, 2 and 3
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1 only

Answer: (a) 1, 2 and 3

Explanation: Biometrics identifies individuals through measurable biological or behavioural characteristics. Iris texture, retinal vascular patterns and voice features can all contribute to authentication. Their reliability differs, so practical systems may combine multiple characteristics and safeguards against impersonation.

Q44. Who is especially associated with the development of induced pluripotent stem-cell technology?

[CGPSC — Practice]

(a) Edward Jenner
(b) Louis Pasteur
(c) Robert Koch
(d) Shinya Yamanaka

Answer: (d) Shinya Yamanaka

Explanation: Shinya Yamanaka and colleagues identified transcription factors that can reprogram somatic cells into induced pluripotent stem cells. The work earned Yamanaka a share of the 2012 Nobel Prize in Physiology or Medicine with John Gurdon.

Q43. Haematopoietic stem cells principally produce which cell family?

[UPSC CDS — Practice]

(a) Plant root hairs
(b) Neurons exclusively
(c) Blood cells
(d) Pancreatic digestive enzymes only

Answer: (c) Blood cells

Explanation: Haematopoietic stem cells reside mainly in bone marrow and generate red cells, white cells and platelets through differentiated precursor lineages. Stem-cell transplantation can restore blood formation after selected cancers, marrow failure and some inherited disorders.

Q42. Which source provides haematopoietic stem cells and is often collected after childbirth?

[UPSC NDA — Practice]

(a) Mature tooth enamel
(b) Umbilical cord blood
(c) Hair shaft without root
(d) Intestinal mucus alone

Answer: (b) Umbilical cord blood

Explanation: Umbilical cord blood contains blood-forming stem and progenitor cells. After birth, it may be collected and stored for potential transplantation. Its clinical usefulness depends on cell dose, donor compatibility and the condition being treated.

Q41. Recombinant DNA methods permit gene transfer:
1. between plant species;
2. from animals to plants;
3. from microorganisms to higher organisms.

[UPSC CSE (Pre) 2013]

(a) All three
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1 only

Answer: (a) All three

Explanation: Recombinant DNA technology does not inherently require donor and recipient to belong to the same species. Subject to successful gene expression and biological compatibility, genetic constructs may move among plants, animals and microorganisms. Thus all three proposed transfers are possible.

Q40. Mesenchymal stromal cells are associated most clearly with formation of:

[State PSC — Practice]

(a) Viruses and bacteriophages
(b) Every type of plant leaf
(c) Only mature neurons without restriction
(d) Bone, cartilage and fat lineages under suitable conditions

Answer: (d) Bone, cartilage and fat lineages under suitable conditions

Explanation: Mesenchymal stromal cells are multipotent stromal populations studied in bone marrow and other tissues. Under appropriate conditions they can show osteogenic, chondrogenic and adipogenic differentiation. Claims of universal cures from such cells are not scientifically justified.

Q39. The cell formed by fusion of sperm and ovum is generally:

[UPSC CSE — Practice]

(a) Haploid mature gamete
(b) A pollen tube
(c) Diploid zygote
(d) A bacterial spore

Answer: (c) Diploid zygote

Explanation: Fertilisation combines haploid genetic contributions from two gametes and normally restores diploidy in the zygote. Early divisions occur through mitosis. Chromosome-number abnormalities can arise, but the usual human zygote contains 46 chromosomes.

Q38. Amniocentesis obtains diagnostic material primarily from:

[WBCS — Practice]

(a) A placental blood vessel without fluid sampling
(b) Amniotic fluid surrounding the fetus
(c) The mother’s lens of the eye
(d) An adult’s bone marrow

Answer: (b) Amniotic fluid surrounding the fetus

Explanation: Amniocentesis samples amniotic fluid containing fetal cells and other biological material. Analyses can assess selected chromosomal and genetic disorders. The procedure involves medical risk, requires informed consent and is subject to laws regulating prenatal testing.

Q37. The enzyme commonly described as the “molecular stitcher” in recombinant DNA technology is:

[RAS / RPSC (Pre) 2013]

(a) DNA ligase
(b) DNA helicase
(c) Restriction endonuclease
(d) RNA polymerase

Answer: (a) DNA ligase

Explanation: DNA ligase forms phosphodiester bonds to seal breaks between compatible DNA ends. Restriction endonucleases cut DNA, while ligases join the resulting fragments. Both enzyme classes underpin conventional recombinant DNA construction and molecular cloning.

Q36. In India, prenatal tests for selecting a child’s sex are:

[MPPSC — Practice]

(a) Equivalent to routine vaccination
(b) An unrestricted household service
(c) Required in every pregnancy
(d) Restricted and prohibited for sex selection under relevant law

Answer: (d) Restricted and prohibited for sex selection under relevant law

Explanation: India’s Pre-Conception and Pre-Natal Diagnostic Techniques law prohibits sex selection and regulates prenatal diagnostic techniques. Medical investigations may be justified for legitimate clinical indications, but using them to disclose or select fetal sex is unlawful.

Q35. What is the defining feature of tissue-specific adult stem cells?

[UPPCS — Practice]

(a) They have no ability to divide
(b) They exist only before fertilisation
(c) They replenish particular cell lineages within tissues
(d) They always generate an entire embryo

Answer: (c) They replenish particular cell lineages within tissues

Explanation: Adult or somatic stem cells help maintain and repair specific tissues. Examples include blood-forming and intestinal stem cells. Their normal differentiation ranges are narrower than those of embryonic pluripotent stem cells, though plasticity depends on cell type.

Q34. Dolly the sheep was produced using which main technique?

[RAS / RPSC — Practice]

(a) Ordinary cross-pollination
(b) Somatic cell nuclear transfer
(c) Artificial selection alone
(d) Bacterial conjugation

Answer: (b) Somatic cell nuclear transfer

Explanation: Dolly was produced by transferring the nucleus of a differentiated adult cell into an enucleated egg, followed by embryonic development and implantation. Born in 1996, she demonstrated that an adult nucleus could be reprogrammed for mammalian development.

Q33. Bacillus thuringiensis is used in agriculture primarily as a source of what?

[Uttarakhand PCS (Pre) 2012]

(a) Biological insecticide
(b) Nitrogen-fixing biofertiliser
(c) Phosphate solvent
(d) Chemical weed killer

Answer: (a) Biological insecticide

Explanation: Bacillus thuringiensis produces insecticidal crystal proteins called Cry toxins. Appropriate Bt formulations can target susceptible insect pests, and selected cry genes have been engineered into crops such as cotton. It is not principally a nitrogen-fixing biofertiliser.

Q32. Why was Dolly considered a landmark in reproductive biotechnology?

[SSC CGL — Practice]

(a) She was the first mammal ever born
(b) Her DNA was entirely synthetic
(c) She grew without an egg cell
(d) She developed from the nucleus of an adult somatic cell

Answer: (d) She developed from the nucleus of an adult somatic cell

Explanation: Dolly was the first mammal cloned successfully from an adult somatic-cell nucleus. Earlier mammalian cloning had used embryonic cells. Her birth provided evidence that differentiated nuclei retain information needed to direct development after suitable reprogramming.

Q31. An enucleated ovum is one from which scientists have removed the:

[SSC CHSL — Practice]

(a) Mitochondria in every case
(b) Extracellular water only
(c) Nuclear genetic material
(d) Cell membrane entirely

Answer: (c) Nuclear genetic material

Explanation: In somatic cell nuclear transfer, the recipient egg normally has its own nuclear chromosomes removed. An introduced donor nucleus is then exposed to egg cytoplasm, which can reprogramme gene expression and support initial embryonic development.

Q30. A clone produced by somatic cell nuclear transfer is most similar in nuclear DNA to:

[SSC MTS — Practice]

(a) An unrelated sperm donor
(b) The donor of the somatic-cell nucleus
(c) Every animal of the same species
(d) The gestational surrogate necessarily

Answer: (b) The donor of the somatic-cell nucleus

Explanation: The clone’s nuclear genome chiefly reflects the somatic nuclear donor. However, mitochondrial DNA generally derives from the recipient egg, and development is influenced by epigenetic and environmental factors. Therefore genetically related clones need not be phenotypically identical.

Q29. Golden Rice was developed chiefly to increase which nutrient precursor in edible grain?

[UPPCS (Pre) 2011]

(a) Beta-carotene
(b) Vitamin K
(c) Vitamin B12
(d) Vitamin C

Answer: (a) Beta-carotene

Explanation: Golden Rice accumulates beta-carotene, a provitamin A carotenoid, in rice endosperm through engineered biosynthetic pathways. Humans can convert beta-carotene into vitamin A. The crop does not directly manufacture vitamin B12 or automatically eliminate all malnutrition.

Q28. Reproductive cloning aims to:

[RRB NTPC — Practice]

(a) Measure blood sugar only
(b) Copy a single protein in vitro
(c) Produce antibiotics from fungi
(d) Produce a living individual from a cloned embryo

Answer: (d) Produce a living individual from a cloned embryo

Explanation: Reproductive cloning seeks development of a cloned embryo into an offspring. Therapeutic applications associated with nuclear transfer instead focus on deriving cells or tissues for research. Both involve important scientific limitations and ethical questions.

Q27. In molecular biology, gene cloning means:

[RRB Group D — Practice]

(a) Staining bacterial spores
(b) Producing an entire human being
(c) Producing many copies of a chosen DNA fragment
(d) Destroying chromosome ends

Answer: (c) Producing many copies of a chosen DNA fragment

Explanation: Gene cloning creates multiple copies of a selected DNA sequence, often using a vector replicated in a host cell. Molecular cloning is distinct from cloning a whole organism. The amplified gene may later be sequenced or expressed.

Q26. What is the major biological challenge in somatic cell nuclear transfer?

[CGPSC — Practice]

(a) Maintaining the donor animal’s diet
(b) Reprogramming a specialised nucleus to support embryo development
(c) Eliminating all ATP from eggs
(d) Producing only male offspring

Answer: (b) Reprogramming a specialised nucleus to support embryo development

Explanation: An adult somatic nucleus carries epigenetic patterns linked to specialised functions. Egg cytoplasm must reset many of those patterns to permit early development. Incomplete reprogramming contributes to the low efficiency and developmental problems observed in animal cloning.

Q25. What nutritional trait explains the significance of Golden Rice?

[UPSC CSE (Pre) 2010]

(a) Presence of provitamin A in the grain
(b) A threefold yield increase
(c) Production of all essential amino acids
(d) Vitamin D fortification

Answer: (a) Presence of provitamin A in the grain

Explanation: Golden Rice is notable for endosperm beta-carotene, which can be converted by the human body into vitamin A. Its intended public-health benefit addresses vitamin A deficiency. Enhanced provitamin A, rather than universal yield or protein gains, is its defining feature.

Q24. Who pioneered the DNA fingerprinting method in the 1980s?

[UPSC CDS — Practice]

(a) Watson alone
(b) Alexander Fleming
(c) Gregor Mendel
(d) Alec Jeffreys

Answer: (d) Alec Jeffreys

Explanation: Alec Jeffreys developed DNA fingerprinting based on highly variable regions of human DNA. The method transformed forensic identification and family relationship testing. Later technologies increasingly employed PCR-based short tandem repeat analysis for sensitive and standardised profiling.

Q23. Which scientist is widely known as the father of DNA fingerprinting in India?

[UPSC NDA — Practice]

(a) S. N. Bose
(b) C. V. Raman
(c) Lalji Singh
(d) Homi Bhabha

Answer: (c) Lalji Singh

Explanation: Lalji Singh played a pioneering role in establishing DNA fingerprinting technology and its applications in India. His work contributed to forensic genetics and population research. Internationally, the original DNA fingerprinting technique is credited to Alec Jeffreys.

Q22. An STR marker consists of:

[State PSC — Practice]

(a) A region without any heritable sequence
(b) A short DNA motif repeated consecutively
(c) A long protein with no nucleotides
(d) A chromosome composed only of RNA

Answer: (b) A short DNA motif repeated consecutively

Explanation: Short tandem repeats comprise short DNA motifs repeated end to end at specific genomic loci. Repeat counts can differ among individuals. Their high variability and PCR compatibility make STRs important for forensic profiling and relationship testing.

Q21. In forensic investigation, which evidence may provide DNA for analysis?
1. Blood cells;
2. bone;
3. root-bearing hair;
4. saliva.

[UPPCS (Pre) 2008]

(a) All four
(b) 2 and 3 only
(c) 1 and 2 only
(d) 1, 3 and 4 only

Answer: (a) All four

Explanation: Nucleated blood cells, bone tissue, hair roots and saliva containing shed cells can provide human DNA. Sample suitability depends on preservation, contamination and extraction method. Forensic laboratories use validated procedures and compare selected genetic markers.

[UPSC CSE — Practice]

(a) Bacterial cell walls
(b) Amino-acid polymer chains
(c) Organelle membranes
(d) Short tandemly repeated DNA sequences

Answer: (d) Short tandemly repeated DNA sequences

Explanation: Microsatellite generally denotes DNA loci containing short tandemly repeated units, often one to six nucleotides long. STR is a closely related term. Variation in repeat number supplies useful genetic markers for forensics and population studies.

Q19. A DNA profile used in an identity investigation is commonly generated by comparing:

[WBCS — Practice]

(a) Blood pressure once
(b) Dietary protein content only
(c) Alleles at several variable genetic loci
(d) The colour of teeth alone

Answer: (c) Alleles at several variable genetic loci

Explanation: Forensic DNA profiling compares genetic markers, typically multiple short tandem repeat loci, across samples. A multi-locus profile increases discriminatory power. Laboratories assess match statistics and contamination risks before interpreting possible identity or relatedness.

Q18. Why do identical twins pose a challenge to conventional forensic STR profiling?

[MPPSC — Practice]

(a) They have different genetic codes for every cell
(b) They ordinarily have almost identical inherited STR profiles
(c) Their blood is always the same group as everyone else
(d) They contain no DNA

Answer: (b) They ordinarily have almost identical inherited STR profiles

Explanation: Monozygotic twins originate from one early embryo and usually share conventional STR profiles. Highly sensitive sequencing may sometimes detect post-zygotic differences, but routine forensic profiles often cannot distinguish them. Other evidence can therefore be crucial.

Q17. What technique seeks to locate genes on chromosomes and determine their relative positions?

[Uttarakhand PCS (Pre) 2006]

(a) Gene mapping
(b) Protein crystallisation
(c) Fermentation
(d) Artificial insemination

Answer: (a) Gene mapping

Explanation: Gene mapping establishes the approximate or exact chromosomal locations of genes or genetic markers. Genetic linkage analysis and physical sequence data offer complementary information. Mapping aids disease-gene discovery, crop breeding and understanding inheritance.

Q16. Which biological material can be useful for DNA identification if it contains intact cells or recoverable DNA?

[UPPCS — Practice]

(a) Pure distilled water only
(b) Refined salt
(c) Sterile glass
(d) Saliva

Answer: (d) Saliva

Explanation: Saliva often contains shed human epithelial cells that supply DNA. Blood, bone, tissue and hair roots may also provide genetic material. Recoverability and profile quality depend on the sample condition, collection technique and possible contamination.

Q15. Which method of identification relies on unique patterns in the coloured ring surrounding the pupil?

[RAS / RPSC — Practice]

(a) Chromosomal banding
(b) DNA barcoding
(c) Iris recognition
(d) Fingerprint powdering

Answer: (c) Iris recognition

Explanation: Iris-recognition systems analyse distinctive textures in the iris using digital imaging and pattern comparison. They are a biometric identification technique, not DNA analysis. Quality can depend on illumination, camera angle, eyewear and presentation-attack protection.

Q14. Which of the following is a behavioural biometric rather than a genetic marker?

[SSC CGL — Practice]

(a) SNP genotype
(b) Voice pattern
(c) Mitochondrial haplotype
(d) STR allele

Answer: (b) Voice pattern

Explanation: Voice recognition uses measurable acoustic and behavioural features influenced by anatomy and speaking habits. In contrast, STRs, SNPs and mitochondrial haplotypes are DNA-based genetic features. Voice biometrics may be affected by illness, environment and recording quality.

Q13. DNA profiling can be used for which purpose?

[UPPCS (Mains) 2004]

(a) All these uses
(b) Paternity determination only
(c) Wildlife population studies only
(d) Criminal identification only

Answer: (a) All these uses

Explanation: DNA profiles compare variable genetic markers to distinguish individuals or infer relationships. They are applied in forensics, parentage assessment and conservation genetics. Interpretation requires controls, statistical assessment and attention to sample contamination.

Q12. DNA barcoding typically identifies an animal species using variation in a standard segment of:

[SSC CHSL — Practice]

(a) Ribosomal protein in blood
(b) Human insulin gene only
(c) Plant chlorophyll pigment
(d) Mitochondrial COI gene

Answer: (d) Mitochondrial COI gene

Explanation: A common animal DNA barcode comes from part of the mitochondrial cytochrome c oxidase subunit I gene. Barcoding compares sequence variation against reference records to identify species. Different markers are preferred for plants, fungi and other groups.

Q11. What does the term bioremediation mean?

[SSC MTS — Practice]

(a) Painting polluted land green
(b) Removing air pressure from soil
(c) Using organisms or biological processes to reduce pollution
(d) Heating all wastewater to boiling

Answer: (c) Using organisms or biological processes to reduce pollution

Explanation: Bioremediation uses microorganisms, plants or their biological activities to remove, break down or immobilise contaminants. Many organic pollutants can be degraded biologically. The approach is site-specific, and some substances such as heavy-metal elements cannot be destroyed.

Q10. A bioreactor in industrial biotechnology is a vessel mainly designed to:

[RRB NTPC — Practice]

(a) Record gravitational waves
(b) Grow cells or conduct controlled biological reactions
(c) Separate planetary gases
(d) Store only dry minerals

Answer: (b) Grow cells or conduct controlled biological reactions

Explanation: Bioreactors support biological processes under controlled conditions such as temperature, pH, mixing and oxygen supply. They are used to produce enzymes, fermented products, pharmaceuticals and cell-derived materials. Different organisms require different reactor designs.

Q9. In India, the then Genetic Engineering Approval Committee functioned under which Union ministry?

[UPSC CSE (Pre) 2003]

(a) Ministry of Environment and Forests
(b) Ministry of Agriculture
(c) Ministry of Commerce
(d) Ministry of Rural Development

Answer: (a) Ministry of Environment and Forests

Explanation: The committee responsible for key approvals involving genetically engineered organisms was associated with the environment ministry. It is now commonly called the Genetic Engineering Appraisal Committee. The institutional name and current regulations should not be confused with wording used in the 2003 paper.

Q8. Which microorganism is widely used for commercial ethanol fermentation?

[RRB Group D — Practice]

(a) Plasmodium vivax
(b) Mycobacterium tuberculosis
(c) Influenza virus
(d) Saccharomyces cerevisiae

Answer: (d) Saccharomyces cerevisiae

Explanation: The yeast Saccharomyces cerevisiae converts sugars into ethanol and carbon dioxide during fermentation. Strain improvement and process optimisation increase productivity. Biotechnology includes traditional fermentation as well as modern genetic and cellular engineering.

Q7. Why are immobilised enzymes sometimes preferred in industrial bioprocessing?

[CGPSC — Practice]

(a) They contain no amino acids
(b) They work only at freezing temperatures
(c) They may be reused and separated more easily from products
(d) They never lose activity

Answer: (c) They may be reused and separated more easily from products

Explanation: Immobilising enzymes on or within a support can improve reusability, handling and product separation. Stability may also improve under suitable conditions. However, mass-transfer limitations and enzyme deactivation remain possible, so immobilisation is not always superior.

Q6. Which industrial application commonly uses microbial recombinant chymosin?

[UPSC CDS — Practice]

(a) Petroleum drilling exclusively
(b) Cheese making
(c) Steel smelting
(d) Glass colouring

Answer: (b) Cheese making

Explanation: Chymosin is a milk-clotting enzyme used in cheesemaking. Recombinant microorganisms can produce chymosin without relying entirely on extraction from calf stomachs. The product illustrates an industrial enzyme generated through molecular biotechnology.

Q5. When a single gene influences several distinct phenotypic traits, the phenomenon is called:

[UPSC CSE (Pre) 2002]

(a) Pleiotropy
(b) Apomixis
(c) Polyploidy
(d) Polyteny

Answer: (a) Pleiotropy

Explanation: Pleiotropy occurs when one gene contributes to multiple observable traits. A change in that gene may consequently influence several organs or physiological functions. Sickle-cell disease provides a familiar example, linking haemoglobin variation with diverse clinical consequences.

Q4. Phytoremediation is the use of which organisms to treat contaminated surroundings?

[UPSC NDA — Practice]

(a) Viruses only
(b) Fish alone
(c) Protozoa only
(d) Plants

Answer: (d) Plants

Explanation: Phytoremediation uses plants and associated root-zone processes to extract, stabilise or transform certain environmental pollutants. Its suitability varies with contaminant type, root depth and growth conditions. It is often slower than aggressive engineering-based cleanup methods.

Q3. A biosensor combines biological recognition with:

[State PSC — Practice]

(a) An entire planted forest
(b) Only a mechanical gear
(c) A transducer that generates a measurable signal
(d) A compulsory living human donor

Answer: (c) A transducer that generates a measurable signal

Explanation: A biosensor links a biological recognition element, such as an enzyme or antibody, with a device that converts the interaction into a signal. Biosensors are used in glucose monitoring, food testing and environmental analysis.

Q2. Which statement best captures an important biosafety principle for genetically engineered organisms?

[UPSC CSE — Practice]

(a) Assume all engineered organisms are equally dangerous
(b) Assess risks case by case before environmental or clinical use
(c) Permit release without any evaluation
(d) Ignore gene transfer and ecological effects

Answer: (b) Assess risks case by case before environmental or clinical use

Explanation: Biosafety assessments consider an organism, its introduced trait, intended use and receiving environment. Issues may include allergenicity, unintended effects, gene flow and ecological interactions. Evidence-based regulation aims to balance potential benefits against identifiable risks.

Q1. Which molecular method is especially useful in testing the biological paternity of a child?

[UP Lower Subordinate (Pre) 2002]

(a) DNA fingerprinting
(b) Artificial cloning
(c) Recombinant hormone synthesis
(d) Gene therapy

Answer: (a) DNA fingerprinting

Explanation: A child inherits genetic variants from both biological parents. DNA profiling examines multiple variable loci to assess whether the alleged parent contributed the expected alleles. The interpretation relies on population statistics and reliable laboratory procedures.

Q150. Consider genetic medicines: 1. They can correct or compensate for defective genes. 2. Engineered viruses and lipid nanoparticles may deliver them. 3. They always rewrite the entire genome. Which are correct?

Q149. What is the fundamental hereditary material of most cellular organisms?

Q148. Which nucleotide base pairs with adenine in ordinary double-stranded DNA?

Q147. Which sugar is present in the backbone of DNA?

Q146. A DNA nucleotide consists of which three components?

Q145. Regarding the GenomeIndia Project, assess: 1. It forms part of the Human Genome Project. 2. It is funded by India’s Department of Biotechnology. 3. It catalogues genetic diversity in Indian populations. Which statements are correct?

Q144. Two strands in the usual DNA double helix run in which orientation?

Q143. Which nitrogenous base is usually found in RNA instead of thymine?

Q142. DNA replication is called semiconservative because each daughter molecule contains:

Q141. Which chemical bond connects successive nucleotides along one DNA strand?

Q140. Regarding monoclonal antibodies, assess: 1. They are laboratory-produced proteins. 2. Specific antigen binding can support immune functions. 3. Antibody candidates have been used investigationally against Nipah infection. Which are correct?

Q139. Which enzyme synthesises DNA using a DNA template during ordinary replication?

Q138. What is a zygote?

Q137. Restriction endonucleases are useful in biotechnology because they:

Q136. Which enzyme is used to join two compatible DNA fragments into a stable molecule?

Q135. Which among the following human hormones was the earliest to be manufactured commercially through recombinant DNA technology?

Q134. The principal purpose of a cloning vector is to:

Q133. The ori sequence of a bacterial plasmid is required primarily for:

Q132. Which selectable marker is often placed in laboratory plasmids?

Q131. The term “sticky ends” refers to DNA fragments having:

Q130. Membrane bioreactors are chiefly associated with which biotechnological application?

Q129. In a recombinant plasmid, the foreign DNA sequence is commonly called the:

Q128. Which microbial process involves uptake of free DNA from the surrounding environment?

Q127. Which technique introduces DNA into cells using short high-voltage electrical pulses?

Q126. What is the primary purpose of downstream processing in recombinant protein production?

Q125. In genetic studies, microsatellite DNA is particularly useful for which purpose?

Q124. Which plant-associated bacterium supplies a widely used gene-transfer system for plants?

Q123. In plant genetic engineering, the term T-DNA refers to:

Q122. What is the principal objective of the polymerase chain reaction (PCR)?

Q121. What does the expression “aerial metagenomics” most directly describe?

Q120. Taq polymerase was originally isolated from which organism?

Q119. During the denaturation step of standard PCR, double-stranded DNA is:

Q118. What determines the approximate starting and ending positions of a PCR amplicon?

Q117. DNA barcoding can help: 1. determine the exact age of an animal; 2. separate visually similar species; 3. identify undeclared species in processed foods. Which are valid uses?

Q116. Which laboratory method separates DNA fragments mainly by their migration through a gel in an electric field?

Q115. In typical agarose electrophoresis, DNA migrates towards the:

Q114. Which technique reads the order of nucleotides in a DNA sample?

Q113. In vaccine-platform terminology, which pair is accurate: 1. Covishield uses an mRNA vaccine platform; 2. Sputnik V uses a viral vector; 3. Covaxin contains inactivated virus?

Q112. A genomic library normally contains:

Q111. A complementary DNA (cDNA) library differs from a genomic library because it is derived from:

Q110. Which enzyme creates DNA using RNA as its template?

Q109. Consider recombinant-vector vaccines: 1. Genetic engineering is used in their design. 2. Certain viruses and bacteria serve as gene-delivery vectors. Which statements are correct?

Q108. What does the term “metagenomics” most closely mean?

Q107. The Cas9 protein functions mainly as a:

Q106. What provides target-sequence recognition in standard CRISPR-Cas9 editing?

Q105. Which statements about mitochondrial replacement therapy are correct? 1. It may be performed before or after fertilisation. 2. Mitochondrial DNA is ordinarily transmitted maternally.

Q104. The expansion of CRISPR includes which phrase?

Q103. An “off-target effect” in genome editing occurs when:

Q102. Compared with a conventional Cas9 double-strand break, a base editor is designed primarily to:

Q101. The names Bollgard I and Bollgard II refer primarily to genetically modified varieties of which crop?

Q100. Prime editing is distinguished by its use of:

Q99. Which type of mutation is most directly associated with the insertion or deletion of bases not divisible by three in a coding sequence?

Q98. Gene silencing by small interfering RNA primarily targets which molecule?

Q97. Which uses of present-day biotechnology are scientifically possible? 1. Genetic modification of sperm- or egg-forming cells. 2. Editing an early human embryo. 3. Introducing human induced pluripotent stem cells into animal embryos.

Q96. In genetic engineering, a promoter is needed chiefly to:

Q95. A reporter gene such as GFP is included in experiments largely to:

Q94. What was the central objective of the Human Genome Project?

Q93. In an older biotechnology MCQ, which claim was officially treated as the incorrect one?

Q92. Approximately how many protein-coding genes are recognised in the human genome?

Q91. Bioinformatics is best described as the application of which discipline to biological data?

Q90. What is the central purpose of genome annotation?

Q89. Cas9, frequently mentioned alongside CRISPR, is best described as which of the following?

Q88. Genome-wide association studies usually seek associations between:

Q87. What is a single-nucleotide polymorphism (SNP)?

Q86. In sequence comparison, homology means that genes or sequences:

Q85. RNA interference (RNAi) technology suppresses gene expression principally through which mechanism?

Q84. Which technique is chiefly used to compare thousands of gene-expression measurements simultaneously?

Q83. An organism’s complete protein complement under specified conditions is called its:

Q82. The main target of Bt cotton technology is resistance against:

Q81. DNA fingerprinting depends most fundamentally upon which feature?

Q80. Which biological source provides the cry genes widely used in insect-resistant crops?

Q79. The insecticidal activity of many Bt Cry proteins is associated with:

Q78. Golden Rice gains its yellow-orange appearance mainly from accumulation of:

Q77. In the pair “CRISPR–Cas9 — particle physics”, what is wrong?

Q76. Flavr Savr tomato was engineered primarily to alter which process?

Q75. What is antisense RNA designed to do in a gene-regulation experiment?

Q74. Which genetically modified crop was approved for commercial cultivation in India in 2002?

Q73. Choose correct statements about environmental bioremediation: 1. It enhances natural microbial degradation. 2. All heavy metals can be completely degraded biologically. 3. Engineered microbes may be used.

Q72. The purpose of an insect-resistance refuge strategy around Bt crops is primarily to:

Q71. Which property is targeted by engineering salt-tolerant crop varieties?

Q150. Consider genetic medicines:
1. They can correct or compensate for defective genes.
2. Engineered viruses and lipid nanoparticles may deliver them.
3. They always rewrite the entire genome.

Which are correct?

Q145. Regarding the GenomeIndia Project, assess:
1. It forms part of the Human Genome Project.
2. It is funded by India’s Department of Biotechnology.
3. It catalogues genetic diversity in Indian populations.

Which statements are correct?

Q140. Regarding monoclonal antibodies, assess:
1. They are laboratory-produced proteins.
2. Specific antigen binding can support immune functions.
3. Antibody candidates have been used investigationally against Nipah infection.

Which are correct?

Q117. DNA barcoding can help:
1. determine the exact age of an animal;
2. separate visually similar species;
3. identify undeclared species in processed foods.

Which are valid uses?

Q109. Consider recombinant-vector vaccines:
1. Genetic engineering is used in their design.
2. Certain viruses and bacteria serve as gene-delivery vectors.

Which statements are correct?

Q105. Which statements about mitochondrial replacement therapy are correct?
1. It may be performed before or after fertilisation.
2. Mitochondrial DNA is ordinarily transmitted maternally.

Q97. Which uses of present-day biotechnology are scientifically possible?
1. Genetic modification of sperm- or egg-forming cells.
2. Editing an early human embryo.
3. Introducing human induced pluripotent stem cells into animal embryos.

Q73. Choose correct statements about environmental bioremediation:
1. It enhances natural microbial degradation.
2. All heavy metals can be completely degraded biologically.
3. Engineered microbes may be used.

Q69. How can sequencing crop genomes help agriculture?
1. Locate disease- and drought-resistance markers.
2. Accelerate breeding programmes.
3. Study crop–pathogen interactions.

Q65. A bacteriophage can be used in genetic engineering because it:
1. infects bacteria;
2. can carry genetic material into bacterial cells.

Q45. Apart from ordinary fingerprints, which characteristics can support biometric identification?
1. Iris patterns;
2. retinal patterns;
3. voice characteristics.

Q41. Recombinant DNA methods permit gene transfer:
1. between plant species;
2. from animals to plants;
3. from microorganisms to higher organisms.

Q21. In forensic investigation, which evidence may provide DNA for analysis?
1. Blood cells;
2. bone;
3. root-bearing hair;
4. saliva.