Every Applied Biology question CSIR-NET Life Sciences has set in its last 11 papers, sorted by topic, with 16 of them solved step by step. Answers follow NTA’s final answer keys.
Unit 12 of the CSIR-NET Life Sciences syllabus, Applied Biology, covers microbial fermentation and bioproducts, transgenic plants and animals, breeding and marker-assisted selection, bioresources, biosensors, bioremediation, and molecular diagnosis and health. We went through all 11 papers from February 2022 to June 2025 and pulled out every question from this unit. It is one of the smaller units.
How much of the paper is Applied Biology?
Across the 11 papers, 64 of the 1,375 Part B and Part C questions (4.7%) came from Unit 12. That ranks it twelfth of the 13 units. 37 of the 64 were 4-mark Part C questions.
| Paper | Part B | Part C | Total |
|---|---|---|---|
| June 2025 | 1 | 5 | 6 |
| December 2024, Shift 1 | 1 | 3 | 4 |
| December 2024, Shift 2 | 5 | 0 | 5 |
| June 2024, Shift 1 | 1 | 4 | 5 |
| June 2024, Shift 2 | 3 | 4 | 7 |
| December 2023, Shift 1 | 3 | 3 | 6 |
| December 2023, Shift 2 | 2 | 4 | 6 |
| June 2023, Shift 1 | 2 | 1 | 3 |
| June 2023, Shift 2 | 3 | 3 | 6 |
| February 2022, Shift 1 | 3 | 6 | 9 |
| February 2022, Shift 2 | 3 | 4 | 7 |
| All 11 papers | 27 | 37 | 64 |
Which Applied Biology topics come up most
Transgenic Plants & Animals and Microbial Fermentation & Bioproducts together account for 61% of the unit’s questions.
16 solved Applied Biology PYQs
One or two from each major subtopic, from different papers. Try each one before you open the solution.
Which of the following enzymes is used for conversion of blood glucose to gluconolactone in commercially available blood glucometer?
- 1Glucose oxidase
- 2Glucose reductase
- 3Glucose dehydrogenase
- 4Gluconolactonase
Show answer and solution
Most glucometer strips use glucose oxidase (GOx, with FAD) to oxidise glucose to gluconolactone. The electrons pass through a mediator, or through H2O2, to the electrode, and the current is proportional to glucose. Some newer strips use glucose dehydrogenase instead, but glucose oxidase is the standard answer.
Which one of the following is NOT required in the blood glucose biosensor?
- 1Glucose oxidase as biologically active component
- 2Electrode as electrochemical transducer
- 3Piezoelectric crystal as sensor
- 4FAD as coenzyme of glucose oxidase
Show answer and solution
A glucose biosensor needs a biological recognition element (glucose oxidase, with its FAD cofactor) and an electrochemical transducer, an electrode that measures current or H2O2. A piezoelectric crystal belongs to mass-sensitive biosensors such as the quartz crystal microbalance, not to glucometers.
A glucose biosensor exhibits Michaelis-Menten kinetics with a maximum current response, Imax = 250 μA, and a Michaelis constant, Km = 5.2 mM. If the glucose concentration in a sample is 3.4 mM, what is the current response (I) of the biosensor?
- 198.83 μA
- 2250 μA
- 329.06 μA
- 473.52 μA
Show answer and solution
Answer: (1) 98.83 μA
The biosensor response follows the Michaelis–Menten form, I = Imax[S]/(Km + [S]) = 250 × 3.4/(5.2 + 3.4) = 850/8.6 = 98.8 µA.
The Ti plasmid from Agrobacterium tumefaciens has genes for auxin, cytokinin and opine synthesis while genes for opine catabolism and Vir genes lie outside the T-DNA region. Which one of the following genes are involved in providing carbon source to Agrobacterium in their ecological niche?
- 1Genes for auxin synthesis only.
- 2Genes for auxin as well as cytokinin synthesis.
- 3Genes for opine synthesis and opine catabolism.
- 4Genes for auxin synthesis as well as opine synthesis.
Show answer and solution
Answer: (3) Genes for opine synthesis and opine catabolism.
Opines (octopine, nopaline) are made by the plant from T-DNA opine synthase genes. Only Agrobacterium carries the opine catabolism genes, on the Ti plasmid outside the T-DNA, that let it use them as a source of carbon and nitrogen. Together they turn the crown gall into a feeding niche for the bacterium. The auxin and cytokinin genes only drive tumour growth.
Which one of the following statements about Cre-mediated site-specific recombination at loxP sites is INCORRECT?
- 1When loxP sites flanking a test sequence are oriented in same direction, Cre mediates the excision of the intervening sequence
- 2LoxP sites in inverted orientation around an intervening sequence lead to inversion upon action by Cre recombinase
- 3LoxP sites recognized by the Cre recombinase are palindromic around a spacer sequence
- 4LoxP-Cre system cannot be used to generate translocation between chromosomes.
Show answer and solution
Answer: (4) LoxP-Cre system cannot be used to generate translocation between chromosomes.
Statement 4 is the incorrect one. Cre–lox can generate chromosome translocations: loxP sites placed on two different chromosomes recombine reciprocally, which is used to model cancer translocations. The others are true. Same-orientation sites excise the DNA between them, inverted sites invert it, and loxP is two 13-bp inverted repeats around an 8-bp spacer.
Which one of the following regions of the target gene is NOT used for making an RNAi construct to knock down its expression?
- 15’ UTR of the mature transcript
- 23’ UTR of the mature transcript
- 3Exonic region
- 4Intronic region
Show answer and solution
Answer: (4) Intronic region
RNAi acts on mature cytoplasmic mRNA. The dsRNA or hairpin is processed into siRNAs that guide RISC to a complementary sequence in the transcript. Exons and the 5′ and 3′ UTRs are all present in the mature mRNA, so any of them can be targeted. Introns are spliced out in the nucleus, so a construct against them finds no target.
Which one of the following strategies will generate the most precise mutation at the predetermined location of a plant genome?
- 1CRISPR/Cas9 editing
- 2T-DNA insertion mutagenesis
- 3Transposon mutagenesis
- 4Targeting Induced Local Lesions in Genomes (TILLING)
Show answer and solution
Answer: (1) CRISPR/Cas9 editing
CRISPR/Cas9 is guided by a 20-nt sgRNA to a chosen site next to a PAM, so the change is made exactly where planned. T-DNA and transposon insertions land essentially at random. TILLING screens for chemically induced point mutations that happen to fall in the gene, but cannot choose the base or position.
Which one of the following biofuels is classified as a first-generation biofuel?
- 1Cellulosic ethanol
- 2Bio-ethanol
- 3Lignin-based biofuels
- 4Algal biofuels
Show answer and solution
Answer: (2) Bio-ethanol
First-generation biofuels are made from food crops by established methods. Bioethanol fermented from sugarcane, maize or other starch and sugar crops is the classic example, along with biodiesel from vegetable oils. Cellulosic and lignin-based fuels are second generation (non-food biomass), and algal fuels are third generation.
Which one of the following is NOT typically a product of fermentation?
- 1Cheese
- 2Black tea
- 3Kombucha
- 4Green tea
Show answer and solution
Answer: (4) Green tea
Cheese is made by bacterial fermentation of milk, and kombucha by fermenting sweet tea with a yeast–bacteria culture. Black tea is traditionally called “fermented” tea: its leaves are oxidised by their own polyphenol oxidase after rolling. Green tea is steamed or pan-fired straight away to stop that process, so it is the unfermented product.
In the production of alcohol by fermentation, in the absence of oxygen, yeasts convert glucose to pyruvate and pyruvate to ethanol. Fermentation promotes glycolysis by
- 1Converting acetaldehyde to alcohol to prevent feed-back inhibition
- 2Generating NADH for mitochondrial ATP generation
- 3Preventing toxicity of acetaldehyde
- 4Generating NAD+ for glycolysis
Show answer and solution
Answer: (4) Generating NAD+ for glycolysis
Glycolysis turns NAD+ into NADH at glyceraldehyde-3-phosphate dehydrogenase. Without oxygen there is no respiratory chain to reoxidise it. In yeast, pyruvate is decarboxylated to acetaldehyde, and alcohol dehydrogenase reduces it to ethanol using NADH, regenerating NAD+, so glycolysis can keep making ATP.
Ten bacterial cells are inoculated into 10 ml of Luria broth and grown for 10 hours with shaking at 37°C. What will be the approximate number of bacteria in the flask at the end of 10-hour incubation? (Note: the doubling time of this bacterium in Luria broth is approximately 20 min).
- 1106
- 2108
- 3109
- 41010
Show answer and solution
Answer: (4) 1010
In 10 hours, at one doubling per 20 minutes, there are 30 doublings. 10 × 230 ≈ 10 × 1.07 × 109 ≈ 1010 cells in the flask. That is also about the most a 10 mL LB culture can hold at saturation (around 109 cells/mL).
A culture was started by inoculating the medium with 100 cells having a generation time of 2 hours. Assuming the culture grows in ideal synchrony for at least 24 hours, what will be the number of cells in the culture at 2 hours and 9 hours?
- 12.0 × 102 cells, 1.6 × 103 cells, respectively.
- 22.0 × 102 cells, 2.4 × 103 cells, respectively.
- 32.0 × 104 cells, 3.2 × 103 cells, respectively.
- 42.0 × 104 cells, 1.6 × 108 cells, respectively.
Show answer and solution
Answer: (1) 2.0 × 102 cells, 1.6 × 103 cells, respectively.
With a 2-hour generation time and perfectly synchronous division, all cells divide together every 2 hours. At 2 hours: 100 × 2 = 200. By 9 hours there have been four divisions (at 2, 4, 6 and 8 hours), and the fifth is not due until 10 hours. So 100 × 24 = 1,600.
Which one of the following statements is NOT true for a continuous culture-based fermentation?
- 1The exponential phase of growth is extended.
- 2Nutrients are utilized efficiently and faster.
- 3Risk of contamination is lower than batch fermentation.
- 4A chemostat allows maintenance of growth rate during fermentation.
Show answer and solution
Answer: (3) Risk of contamination is lower than batch fermentation.
Continuous culture (a chemostat) keeps cells in exponential growth at a steady rate and uses nutrients efficiently. But because it runs for days or weeks, with medium constantly added and removed, the risk of contamination is higher than in a batch run, as is the risk of the strain mutating. So statement 3 is false.
To evaluate insulin-dependent diabetes, clinicians prefer evaluating mono-glycated hemoglobin referred to as HbA1c, which occurs due to a nonenzymatic reaction between glucose and a few amino acids in hemoglobin. Which of the following amino acids are likely to be involved in the modification of hemoglobin?
- 1Asparagine and Glutamic acid
- 2Proline and Tryptophan
- 3Glutamine and Aspartic acid
- 4Valine and Lysine
Show answer and solution
Answer: (4) Valine and Lysine
Glucose reacts non-enzymatically, through a Schiff base and Amadori rearrangement, with free amino groups. In HbA1c it attaches to the N-terminal valine of each β chain, and glycation also occurs on ε-amino groups of lysine residues. Because red cells live about 120 days, HbA1c reflects average blood glucose over the previous 2–3 months.
Widal test, a widely used serological test for enteric fever, is a type of
- 1precipitation reaction
- 2agglutination reaction
- 3complement fixation test
- 4immunofluorescence detection
Show answer and solution
Answer: (2) agglutination reaction
The Widal test mixes the patient’s serum with killed Salmonella Typhi and Paratyphi suspensions, which carry the O (somatic) and H (flagellar) antigens. Antibodies clump the bacteria, so it is a tube or slide agglutination reaction, read as the highest dilution that still agglutinates.
What is the nature of India’s indigenous COVID-19 vaccine?
- 1It is an mRNA vaccine (for expression of viral spike protein)
- 2It is a preparation of inactivated whole virus
- 3It is a preparation of attenuated SARSCov2 virus
- 4It is a recombinant, replication-deficient chimpanzee adenovirus vector encoding the SARS-CoV-2 Spike (S) glycoprotein
Show answer and solution
Answer: (2) It is a preparation of inactivated whole virus
Covaxin (Bharat Biotech with ICMR–NIV) is a whole-virion SARS-CoV-2 vaccine inactivated with β-propiolactone and adjuvanted with alum plus a TLR7/8 agonist. Covishield is the chimpanzee adenovirus-vector vaccine, made under licence from Oxford and AstraZeneca. Pfizer and Moderna make mRNA vaccines.
All 64 Applied Biology questions, by subtopic
Each link opens the question on its full paper page. Press Show answer and solution there to see NTA’s final key and a worked solution.
Transgenic Plants & Animals (28 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q91 | C | The following statements are made about transgenic mice technologies: Which one of the following options represents the combination of all… |
| Dec 2024 S1, Q135 | C | Following statements are made with respect to the production of transgenic plants. Which one of the following options represents all… |
| Dec 2024 S2, Q62 | B | Which one of the following statements is correct? |
| Jun 2024 S1, Q32 | B | A researcher overexpresses the full-length genomic sequence of rice GAPDH gene under a CaMV35S promoter in transgenic rice. Which one of… |
| Jun 2024 S1, Q78 | C | Given below are a few statements on transgenic plants. Which one of the following options represents a combination of only correct statements? |
| Jun 2024 S1, Q97 | C | A researcher used CRISPR-Cas9 system and observed a different type of mutation in two alleles of a target gene in a T0 transgenic plant… |
| Jun 2024 S2, Q52 | B | The Ti plasmid from Agrobacterium tumefaciens has genes for auxin, cytokinin and opine synthesis while genes for opine catabolism and Vir… |
| Jun 2024 S2, Q57 | B | Which one of the following statements is INCORRECT? |
| Jun 2024 S2, Q100 | C | Following statements were made for the production of cisgenic plants. Which one of the following options represents the combination of all… |
| Dec 2023 S1, Q118 | C | A new strain of bacteria was created by introducing an artificial operon, to allow bacterial cells to grow in the presence of iron. The… |
| Dec 2023 S1, Q138 | C | A transgenic line was developed in mustard. The T0 transgenic line was selfed and the insertion of transgene was analyzed in the parental… |
| Dec 2023 S1, Q139 | C | The Cre-LoxP system was used to knock-out the p53 gene from the mice lungs. An immunoblot analysis was carried out as shown below. The… |
| Dec 2023 S2, Q65 | B | Which one of the following strategies will generate the most precise mutation at the predetermined location of a plant genome? |
| Dec 2023 S2, Q137 | C | Given below is a schematic representation of the T-DNA region of a binary vector used for genetic transformation of plants. The figure… |
| Dec 2023 S2, Q145 | C | Which one of the following intermediate enzymatic reactions would be most effective in facilitating ligation of a blunt-ended insert… |
| Jun 2023 S1, Q65 | B | Which one of the following types of promoters would NOT be used within the T-DNA for expression of a negative selection marker gene for… |
| Jun 2023 S1, Q138 | C | A transgenic plant having a homozygous single-copy insertion for trait A was re-transformed by Agrobacterium-mediated transformation with a… |
| Jun 2023 S2, Q65 | B | Which one of the following statements is correct? |
| Jun 2023 S2, Q139 | C | Given below are some statements that are associated with transgenic plants. Each statement has a blank space indicated by ‘_______’. Which… |
| Jun 2023 S2, Q140 | C | Given below are some statements with blank spaces indicated by ‘_______’. Which one of the following options has the correct sequence of… |
| Feb 2022 S1, Q65 | B | Which one of the following regions of the target gene is NOT used for making an RNAi construct to knock down its expression? |
| Feb 2022 S1, Q137 | C | Given below are a few statements on technologies/concepts related to development of transgenic plants: Which one of the following options… |
| Feb 2022 S1, Q141 | C | Inverse PCR is performed for site-directed mutagenesis with complementary primers (having the desired mutation) using a plasmid having the… |
| Feb 2022 S2, Q31 | B | Which one of the following statements about Cre-mediated site-specific recombination at loxP sites is INCORRECT? |
| Feb 2022 S2, Q66 | B | Which one of the following statements related to genetic transformation of plants is correct? |
| Feb 2022 S2, Q138 | C | In a forward genetic screen to investigate the heat stress response in Arabidopsis, a team of researchers identified an uncharacterized… |
| Feb 2022 S2, Q139 | C | Given below is a figure representing expression levels of transgenic protein in ten independent transgenic plants generated using the same… |
| Feb 2022 S2, Q145 | C | Which one of the following combinations of enzymes used for cloning a linear insert fragment into a digested plasmid vector would have the… |
Microbial Fermentation & Bioproducts (11 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q66 | B | Which one of the following biofuels is classified as a first-generation biofuel? |
| Dec 2024 S2, Q56 | B | Ten bacterial cells are inoculated into 10 ml of Luria broth and grown for 10 hours with shaking at 37°C. What will be the approximate… |
| Jun 2024 S1, Q121 | C | The nitrogen fixing bacterium, Rhizobium leguminosarum, isolated from the root nodules of garden pea (Pisum sativum) is cultured in a petri… |
| Jun 2024 S1, Q143 | C | Following statements are made regarding the nature of the chromosomes in bacteria. Which one of the following options represents the… |
| Jun 2024 S2, Q38 | B | The following graphs represent plots for the volume (dotted lines) and bacterial viable cell count curves (solid line) for a fermenter… |
| Dec 2023 S1, Q64 | B | During animal cell culture, which one of the following cell types would NOT require trypsin for passaging? |
| Dec 2023 S1, Q65 | B | In the production of alcohol by fermentation, in the absence of oxygen, yeasts convert glucose to pyruvate and pyruvate to ethanol… |
| Jun 2023 S2, Q67 | B | Which one of the following statements is NOT true for a continuous culture-based fermentation? |
| Jun 2023 S2, Q68 | B | Which one of the following is NOT typically a product of fermentation? |
| Feb 2022 S1, Q139 | C | A culture was started by inoculating the medium with 100 cells having a generation time of 2 hours. Assuming the culture grows in ideal… |
| Feb 2022 S1, Q145 | C | Pichia pastoris is a good host for producing human proteins for therapeutic use. Given below are some statements on the reasons for its… |
Molecular Diagnosis, Genomics & Health (6 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2024 S2, Q95 | C | The following statements refer to mechanisms that may confer resistance to antibiotics in bacteria. Which one of the following options… |
| Jun 2024 S2, Q121 | C | Following statements have been made about vaccines. Which one of the following options represents the combination of all correct statements? |
| Jun 2024 S2, Q132 | C | The following statements are made regarding formulation of the advanced candidate antimalaria vaccine RTS,S. Which one of the following… |
| Dec 2023 S2, Q64 | B | To evaluate insulin-dependent diabetes, clinicians prefer evaluating mono-glycated hemoglobin referred to as HbA1c, which occurs due to a… |
| Feb 2022 S1, Q68 | B | Widal test, a widely used serological test for enteric fever, is a type of |
| Feb 2022 S2, Q65 | B | What is the nature of India’s indigenous COVID-19 vaccine? |
Breeding & Marker-Assisted Selection (5 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q141 | C | Shown in the table are some cultivated crops (Column X) and the chromosomal ploidy (Column Y). Which one of the following options… |
| Jun 2023 S1, Q66 | B | Which one of the following statements regarding molecular markers for genotyping is INCORRECT? |
| Jun 2023 S2, Q138 | C | Given below are a few statements on mapping populations and marker-assisted selection (MAS): Which one of the following options represents… |
| Feb 2022 S1, Q64 | B | Which one of the following statements is correct? |
| Feb 2022 S2, Q140 | C | In recent decades, the use of genetic markers has allowed the rapid introgression and selection of desired breeding stocks in advance… |
Biosensors (4 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q95 | C | A glucose biosensor exhibits Michaelis-Menten kinetics with a maximum current response, Imax = 250 μA, and a Michaelis constant, Km = 5.2… |
| Dec 2024 S1, Q127 | C | The following statements describe a few basic features of the interferometric reflectance imaging sensor used as a biosensing platform… |
| Dec 2024 S2, Q42 | B | Which of the following enzymes is used for conversion of blood glucose to gluconolactone in commercially available blood glucometer? |
| Dec 2023 S1, Q66 | B | Which one of the following is NOT required in the blood glucose biosensor? |
Crop Diseases & Pathogens (4 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q116 | C | Given below are certain plant diseases and the pathogens responsible. Which one of the following options correctly matches the disease with… |
| Dec 2024 S1, Q94 | C | The table given below provides a comprehensive list of selected plant diseases (Column X) and possible causal pathogens (Column Y). Which… |
| Dec 2024 S2, Q60 | B | Which one of the following plant pathogens has the most prolonged symptomless infection phase? |
| Feb 2022 S1, Q117 | C | Given below are the names of diseases caused in rice in Column X and the names of the disease-causing organisms in Column Y. Which one of… |
Bioresources & Uses of Biodiversity (3 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q79 | C | Given below is a table listing the names of compounds/products derived from animals or plants (Column X) and their use/application (Column… |
| Dec 2023 S2, Q120 | C | Following table shows cultivated crops (Column X) and the continents where their centers of origin (Column Y) are situated: Which one of… |
| Dec 2023 S2, Q124 | C | The following table shows common millets (Column X) and their scientific names (Column Y): Which one of the following options represents… |
Bioremediation & Phytoremediation (3 questions)
| Paper and question | Part | Question |
|---|---|---|
| Dec 2024 S1, Q44 | B | Which experiment would best validate the bioremediation potential of a microbial strain degrading oil spills in seawater? |
| Dec 2024 S2, Q41 | B | Which experiment would be most effective in assessing the synergistic role of mycorrhizal fungi and plants in phytoremediation? |
| Feb 2022 S1, Q134 | C | Given below are some terms and concepts related to phytoremediation in Column A and B Which one of the following options represents the… |
PYQs for every CSIR-NET unit
How to revise Applied Biology with these questions
- Start with the two biggest subtopicsTransgenic Plants & Animals and Microbial Fermentation & Bioproducts are where most of the marks have been. Revise them first.
- Attempt before you readWork through a subtopic’s questions on paper, then check them against the answer keys.
- Find the repeatsThe same ideas keep coming back in new wording. When you get one wrong, look for its earlier version in the list above.
- Finish with a full paperTake a whole paper in live exam mode to practise choosing which Part C questions to attempt.
Keep going
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p class=”lbq-src”>Source: CSIR-NET Life Sciences question papers and final answer keys, National Testing Agency, February 2022 to June 2025. Subtopic tags, difficulty ratings and solutions: Lesson Basket.
