Biotechnology & Genetics MCQs for UPSC Prelims

Correct answer: A - To make it pest-resistant

Bt-brinjal is engineered by inserting a gene from the soil bacterium Bacillus thuringiensis that produces a protein toxic to specific insect pests such as the fruit and shoot borer, so the objective is pest resistance, option (a). It is not aimed at improving taste or nutrition (b), at conferring drought resistance (c), or at extending shelf life (d); the Bt gene specifically provides insect resistance.

Correct answer: A - Studying the evolutionary relationships among various species of fauna

Microsatellites (also called short tandem repeats) are short, highly variable repeating DNA sequences. Because their high polymorphism makes them excellent genetic markers, they are used to study genetic diversity, population structure, parentage and evolutionary relationships among species of fauna - so option (a) is correct. They are also central to DNA fingerprinting. Stimulating stem-cell differentiation (b) depends on growth factors and signalling molecules, not microsatellites. Clonal propagation of horticultural plants (c) uses tissue culture and vegetative methods. Assessing drug efficacy (d) relies on clinical trials and pharmacology, unrelated to microsatellite markers.

Correct answer: A - Controlling the viral diseases spread by mosquitoes

The Wolbachia method refers to controlling mosquito-borne viral diseases, so option (a) is correct. Mosquitoes are infected with Wolbachia bacteria, which reduces their ability to transmit viruses like dengue, Zika and chikungunya. The method has nothing to do with converting crop residues, making biodegradable plastics, or producing biochar, so the other options are unrelated and incorrect.

Correct answer: B - 2 and 3 only

Statements 2 and 3 are correct. Stem cells are used to screen candidate drugs for efficacy and toxicity on human-like tissue in the laboratory, and they underpin medical therapies such as bone marrow (haematopoietic stem cell) transplantation, with wider regenerative applications under trial. Statement 1 is wrong because stem cells are not restricted to mammals; they exist across the animal kingdom (planaria and hydra regenerate through them) and analogous meristematic cells exist in plants. Since statement 1 is false, options (a) and (d) fall, and (c) wrongly drops the valid drug-screening use.

Correct answer: B - developing genetically modified crop plants

Bollgard I and Bollgard II are brand names of genetically modified Bt cotton in which genes from the bacterium Bacillus thuringiensis are inserted to make the plants resistant to bollworm pests, so they belong to the context of developing genetically modified crop plants. They are not techniques of clonal (tissue-culture) propagation, nor methods for manufacturing plant growth hormones, nor processes for producing biofertilizers, so the other three options are incorrect.

Correct answer: D - 1, 2 and 3

All three kinds of organisms supply biopesticides, so (d) is correct. Bacteria such as Bacillus thuringiensis are the most widely used microbial pesticides. Fungi such as Trichoderma, Beauveria bassiana and Metarhizium are used against soil pathogens and insect pests. Flowering plants also yield botanical pesticides: neem (azadirachtin), pyrethrum from Chrysanthemum flowers, and nicotine from tobacco. Options (a), (b) and (c) each exclude at least one valid source and are therefore wrong.

Correct answer: D - Neither 1 nor 2

Neither statement is correct. In Indian Railways' bio-toilets, decomposition of human waste is carried out by anaerobic bacteria, not a fungal inoculum, so statement 1 is wrong. The end products are mainly methane and carbon dioxide (biogas) along with water, not merely ammonia and water vapour, so statement 2 is wrong. Hence the answer is 'Neither 1 nor 2'.

Correct answer: C - 1, 2 and 4 only

Genetic engineering of crops has been pursued to confer drought tolerance so plants survive water stress (statement 1), to enhance nutritional content such as Golden Rice enriched with provitamin A (statement 2), and to extend shelf life by delaying ripening and spoilage, as in the Flavr Savr tomato (statement 4); all three are real prospects. Statement 3, engineering plants specifically to grow and photosynthesise inside spaceships or space stations, is not an established purpose for which GE plants have been created, so it is wrong. Therefore the correct combination is 1, 2 and 4 only.