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.
