Science and Technology (Part-I)

Total Questions: 50

41. To meet its rapidly growing energy demand, some opine that India should pursue research and development on thorium as the future fuel of nuclear energy. In this context, what advantage does thorium hold over uranium? [2012-1]

1. Thorium is far more abundant in nature than uranium.

2. On the basis of per unit mass of mined mineral, thorium can generate more energy compared to natural uranium.

3. Thorium produces less harmful waste compared to uranium.

Which of the statements given above is/are correct?

Correct Answer: (d) 1, 2 and 3
Solution:Thorium fuel generates no new bomb-usable material in the waste profile; the waste consists of the radioisotope Uranium-233, or U233, which is virtually impossible to weaponize/ Thorium fuel will generate more energy per unit of mass than uranium fuel by a factor of approximately 30. Thorium is four times more abundant in nature than uranium, and is widely distributed throughout the Earth's crust. All statements in this question are correct.

42. Indiaisanimportantmemberofthe International Thermonuclear Experimental Reactor'. If this experiment succeeds, what is the immediate advantage for India? [2016-1]

Correct Answer: (d) It can build fusion reactors for power generation
Solution:(i) The ITER (International Thermonuclear Experimental Reactor) project aims to make the long-awaited transition from experimental studies of plasma physics to full-scale electricity-producing fusion power stations.

(ii) As such project started in 2006, to find whether Nuclear fusion can be a source of energy and electricity in future.

Hence (d) is the apt choice.

43. In India, why are some nuclear reactors kept under "IAEA Safeguards" while others are not? [2020-1]

Correct Answer: (b) Some use imported uranium and others use domestic supplies
Solution:As per the India-US Civilian Nuclear Deal, India can maintain 2-types of nuclear reactors. Certain reactors, in which we are using the domestic fuel, India can keep them outside the purview of IAEA.

However, the reactors in which we are using imported fuel, they will be mandatorily under the IAEA inspection.

There are at present 22 operational reactors of, which 14 are under the International Atomic Energy Agency (IAEA) safeguards as these use imported fuel.

44. Which of the following professional(s) are more likely to run the risk of a permanent change in their cell's DNA? [1996]

1. Researchers using Carbon 14 isotope

2. X-ray technician

3. Coal miner

4. Dyer and painter

Select the correct answer by using the codes given below:

Correct Answer: (c) 1, 2 and 4
Solution:X-Raytechnique, C and Dyer technique is very important technique for permanent change in DNA. But in coal miner, C amount is very very less. So, there is no risk of change in DNA.
Understanding DNA Changes
• DNA: Deoxyribonucleic acid (DNA) is the genetic material found in all living organisms. It contains the instructions necessary for an organism to develop, survive, and reproduce.
• Permanent Changes: Permanent changes in DNA, also known as mutations, occur when the normal sequence of DNA nucleotides is altered. These alterations can happen due to various factors, including exposure to certain chemicals, radiation, or errors during DNA replication.
• Risk Factors: Some occupations involve regular or significant exposure to agents that can cause mutations (mutagens) or cancer (carcinogens), thereby increasing the risk of such DNA changes in the cells of exposed individuals.

45. Which one of the following techniques can be used to establish the paternity of a child? [1997]

Correct Answer: (d) DNA finger printing
Solution:

DNAfingerprintingtechnology istheprocessofestablishing the biological paternal relationship between individual and his alleged child on the analysis of sample cells taken from each of them.
DNA finger printing can solve cases of rape murder etc.
The key steps involved in generating a DNA fingerprint are:
• Sample collection: DNA is extracted from tissue samples like blood, bone, hair roots, semen, or buccal swab samples.
• DNA extraction: The extracted sample is purified using various chemical processes.
• PCR amplification: Using PCR, the extracted DNA is amplified with specific primers targeting the STR regions of interest.
• Separation: The amplified DNA fragments are separated based on size using gel electrophoresis.
• Detection: The separated DNA fragments of varying sizes appear as bands on the gel and are detected using fluorescent dyes.
• Profile generation: The size and number of repeats in each band are analysed to generate the distinctive DNA profile with the advanced computerised systems.
• Matching: The generated profile is then compared to other DNA profiles in a database to find any matches.

46. Assertion (A): Insect resistant transgenic cotton has been produced by inserting Bt gene. [1999]

Reason (R): The Bt gene is derived from a bacterium.

Correct Answer: (a) Both A and R are true and R is the correct explanation of A
Solution:Assertion (A) states that insect-resistant transgenic cotton has been produced by inserting the Bt gene. Bt stands for Bacillus thuringiensis, which is a bacterium that produces a protein toxic to certain insect pests. By inserting the Bt gene into cotton plants, they can produce this insecticidal protein and become resistant to specific insect pests.

Reason (R) states that the Bt gene is derived from a bacterium. This is true as the Bt gene is sourced from Bacillus thuringiensis, a naturally occurring soil bacterium that produces the insecticidal protein. The gene responsible for producing this protein can be isolated and inserted into the genome of other plants, such as cotton, to confer insect resistance.

Therefore, both Assertion (A) and Reason (R) are true, and Reason (R) provides the correct explanation for Assertion (A).

47. Assertion (A): Dolly was the first cloned mammal. [1999]

Reason (R): Dolly was produced by in vitro fertilization.

Correct Answer: (c) A is true but R is false
Solution:A is true, but R is false. Dolly, indeed, was the first cloned mammal, which makes assertion (A) true. However, the reason (R), stating that Dolly was produced by in vitro fertilization, is false.

Dolly was produced using a technique called Somatic Cell Nuclear Transfer (SCNT). In this process, the nucleus of an egg cell was removed and replaced with the nucleus of a somatic (body) cell from another adult individual. Then, the egg was stimulated to divide, forming an embryo that was identical to the organism that donated the somatic cell. The embryo was then implanted into a surrogate mother.

In vitro fertilization is a different process wherein an egg is fertilised by sperm outside the body. Therefore, this is not the technique used to produce Dolly.

48. Assertion (A): "DNA finger printing" has become a powerful tool to establish paternity and identity of criminals in rape and assault cases. [2000]

Reason (R): Trace evidences such as hairs, saliva and dried semen are adequate for DNA analysis.

Correct Answer: (a) Both A and R are true and R is the correct explanation of A
Solution:

DNA finger printing is the technique which identify paternity and criminals in rape cases, by the help of any tissue sample, hair, saliva or dried semen.
The key steps involved in generating a DNA fingerprint are:
• Sample collection: DNA is extracted from tissue samples like blood, bone, hair roots, semen, or buccal swab samples.
• DNA extraction: The extracted sample is purified using various chemical processes.
• PCR amplification: Using PCR, the extracted DNA is amplified with specific primers targeting the STR regions of interest.
• Separation: The amplified DNA fragments are separated based on size using gel electrophoresis.
• Detection: The separated DNA fragments of varying sizes appear as bands on the gel and are detected using fluorescent dyes.
• Profile generation: The size and number of repeats in each band are analysed to generate the distinctive DNA profile with the advanced computerised systems.
• Matching: The generated profile is then compared to other DNA profiles in a database to find any matches.

49. Insect-resistant cotton plants have been genetically engineered by inserting a gene from a/an : [2000]

Correct Answer: (b) bacterium
Solution:

Insect resistant cotton plants have been genetically engineered by inserting a gene from bacterium Bacillus thuringiensis.
Genetic engineering refers to the direct manipulation of an organism’s genome using advanced DNA technology. It involves the introduction, deletion or modification of genes within an organism’s DNA to produce desirable traits. Genetic engineering has revolutionised fields like agriculture, medicine and biotechnology enabling innovations like disease-resistant crops, synthetic insulin production and gene therapy.
The field of genetic engineering has been propelled by advancements in gene editing technologies such as CRISPR-Cas9, in recent years. Gene editing technologies have revolutionized the ability to manipulate genes, allowing scientists to precisely modify and control genetic material.

50. Hybridoma technology is a new biotechnological approach for commercial production of : [2000]

Correct Answer: (a) monoclonal antibodies
Solution:Hybridoma technology is used to commercially production of monoclonal antibodies. The monoclonal antibodies are protective protein produced by the clone of single immune cell.
Monoclonal antibodies are laboratory-made proteins that mimic the behaviour of antibodies produced by the immune system to protect against diseases and foreign substances.
An antibody attaches itself to an antigen (a foreign substance, usually a disease-causing molecule) and helps the immune system eliminate it from the body.
Monoclonal antibodies are specifically designed to target certain antigens.
Niels K. Jerne, Georges J.F. Köhler and Cesar Milstein were awarded the medicine Nobel Prize in 1984 for their work on the principle for production of monoclonal antibodies.