A researcher used CRISPR-Cas9 to edit a disease-causing mutation in human embryo cells. What ethical concern is most relevant?
Answer: C
Germline (heritable) genetic modifications in humans raise significant ethical concerns about consent, unknown long-term effects, and societal implications, which is why many countries restrict human embryo editing.
Q.2Hard
A biotechnology company wants to develop a drought-resistant wheat variety using genetic engineering. Which genes would be most suitable to introduce?
Answer: B
Aquaporins regulate water transport while osmolyte biosynthetic genes help cells maintain turgor under water stress, both crucial for drought resistance in plants.
Q.3Hard
In the development of Bt Brinjal in India, which Bacillus thuringiensis gene was primarily used and for which pest resistance?
Answer: C
Bt Brinjal (approved for cultivation in 2023 in India) contains the Cry1Ac gene from Bacillus thuringiensis, providing resistance to the eggplant fruit and shoot borer (Leucinodes orbonalis).
Q.4Hard
What is the primary limitation of using bacterial plasmids as vectors for introducing large genes (>50 kb) into eukaryotic cells?
Answer: B
Plasmids typically have limited cloning capacity (usually 5-15 kb), making them unsuitable for large genes. BACs (Bacterial Artificial Chromosomes) or YACs (Yeast Artificial Chromosomes) are preferred for large inserts.
Q.5Hard
A genetically modified organism (GMO) shows unexpected phenotypic changes not related to the introduced transgene. What biological phenomenon best explains this?
Answer: C
When foreign DNA integrates into the genome, it can disrupt endogenous genes or be influenced by local chromatin context (position effect), causing unintended phenotypic changes beyond the transgene's direct effect.
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Q.6Hard
A researcher wants to produce recombinant human insulin in bacteria. Which of the following steps would be MOST critical for ensuring successful protein expression?
Answer: A
Bacterial expression requires prokaryotic regulatory elements such as bacterial promoters and Shine-Dalgarno sequences for proper transcription and translation. The human gene alone won't be recognized by bacterial machinery.
Q.7Hard
Which modern technique allows for the creation of gene edits that can be reversed or made inducible, offering greater control over gene expression?
Answer: C
Epigenetic editing modifies gene expression without altering the DNA sequence itself, making changes potentially reversible. Prime editing offers precise edits with fewer off-targets. Base editing directly converts one DNA base to another. Epigenetic approaches offer the most control and reversibility.
Q.8Hard
Consider a scenario where a genetic engineer develops a drought-resistant crop by introducing an aquaporin gene. Which of the following would be the most appropriate long-term assessment of this GM crop's environmental impact?
Answer: B
Comprehensive environmental impact assessment requires multi-generational studies examining effects on biodiversity, soil health, water systems, and non-target organisms. Short-term yield data alone is insufficient for determining ecological safety.
Q.9Hard
In gene therapy for genetic disorders, what is the primary advantage of using ex vivo gene therapy compared to in vivo therapy?
Answer: B
Ex vivo gene therapy involves editing cells outside the body, allowing for rigorous selection of successfully modified cells and quality control before reimplantation. This reduces risks associated with unsuccessful edits.
Q.10Hard
Which of the following represents the most significant biosafety concern regarding horizontal gene transfer from GM crops to wild relatives?
Answer: B
The spread of herbicide or insect resistance genes to wild relatives creates organisms that are difficult to control and can disrupt ecosystems. This is the primary biosafety concern in several regulatory assessments, particularly for herbicide-resistant crops.
Q.11Hard
A biotechnology company successfully edits a disease-causing gene in human embryonic stem cells using CRISPR-Cas9. Before proceeding with clinical trials, what is the primary regulatory and ethical challenge they would face in India?
Answer: C
Germline (heritable) editing raises profound ethical, religious, and social concerns about modifying the human genome permanently. Most countries, including India, have strict regulations or moratoriums on germline editing applications.
Q.12Hard
What is the primary mechanism by which RNA interference (RNAi) achieves gene silencing?
Answer: A
RNAi uses small interfering RNAs (siRNAs) that guide the RNA-Induced Silencing Complex (RISC) to degrade specific target mRNAs, effectively silencing gene expression post-transcriptionally.
Q.13Hard
In next-generation sequencing-based CRISPR screening, what does 'pooled library screening' allow researchers to identify?
Answer: B
Pooled CRISPR screening uses large libraries of guide RNAs to simultaneously test thousands of genetic perturbations, allowing identification of genes associated with specific phenotypes through NGS readout.
Q.14Hard
Which of the following represents the most significant challenge in applying base editing technology for therapeutic applications?
Answer: B
Base editors convert one nucleotide to another without creating double-strand breaks, but optimizing specificity to edit only intended bases while avoiding unintended modifications remains a significant hurdle.
Q.15Hard
What is the significance of using 'prime editing' technology over conventional CRISPR-Cas9 in genetic engineering applications?
Answer: B
Prime editing fuses Cas9 nickase with reverse transcriptase, allowing creation of diverse genetic modifications from a single RNA template without creating double-strand breaks, offering superior precision and safety.
Q.16Hard
In zinc finger nuclease (ZFN) technology, how many zinc finger domains are typically required to recognize and bind to a specific DNA sequence?
Answer: A
Each zinc finger domain recognizes approximately 3 bp. Three domains recognize 9 bp, which provides adequate specificity for most genomic targets.
Q.17Hard
Which of the following would be the BEST strategy to minimize off-target effects in CRISPR-Cas9 editing of human embryonic stem cells?
Answer: B
High-fidelity Cas9 variants (eSpCas9, SpCas9-HF1) with stringent guide RNA design using prediction tools significantly reduce off-target cleavage in therapeutic applications.
Q.18Hard
In the context of gene therapy vectors, which characteristic makes adeno-associated viruses (AAVs) preferable to lentiviruses for CNS diseases?
Answer: C
AAVs are 25 nm particles with limited packaging (~4.7 kb) but excellent CNS tropism, low immunogenicity, and non-integrating nature, making them safer for neurological applications.
Q.19Hard
Which technique combines microfluidics with next-generation sequencing to analyze single-cell genetic modifications in heterogeneous populations?
Answer: C
scCRISPR-seq enables simultaneous analysis of CRISPR perturbations and transcriptome responses at single-cell level, revealing cellular heterogeneity in gene-edited populations.
Q.20Hard
In base editing technology, what is the critical difference between cytidine and adenosine deaminases in terms of target DNA modification?
Answer: B
Cytidine deaminase (APOBEC) converts cytosine to uracil (paired with G) leading to C-G→T-A transition. TadA adenosine deaminase converts adenosine to inosine (read as G), causing A-T→G-C.
