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.
