Q1: Which one of the following is used in preparing a natural mosquito repellent? (a) Congress grass (b) Elephant grass (c) Lemongrass (d) Nut grass
Solution:
Ans: (c) Lemongrass is a tall herb that is abundantly found in tropical and sub-tropical areas of Asia, Africa and Australia. It is known to be an excellent mosquito repellant. Around 95% of mosquitos from a specific range of species are either killed or completely repelled due to the intense odour of lemongrass oil. Therefore, option (c) is the correct answer.
Q2: With reference to recent developments regarding 'Recombinant Vector Vaccines', consider the following statements:
Genetic engineering is applied in the development of these vaccines.
Bacteria and viruses are used as vectors.
Which of the statements given above is/are correct? (a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2
Solution:
Ans: (c)
Recombinant vector vaccines are made through genetic engineering. The gene that creates the protein for a bacteria or virus is isolated and placed inside another cell's genes. Hence, statement 1 is correct.
Numerous viral vectors are available for vaccine development, such as vaccinia, modified vaccinia virus Ankara, adenovirus, adeno-associated virus, retrovirus/lentivirus, alphavirus, herpes virus, etc. Hence, statement 2 is correct. Therefore, option (c) is the correct answer.
Q3: In the context of hereditary diseases, consider the following statements:
Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of the egg.
A child inherits mitochondrial diseases entirely from mother and not from father.
Which of the statements given above is/are correct? (a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2
Solution:
Ans: (c)
The technological development allows nearly complete replacement of the cytoplasm of egg/embryo, eliminating the transmission of undesired defective mitochondria for patients with inherited mitochondrial diseases, which is called mitochondrial replacement therapy (MRT). These processes use assisted reproductive technology, including in vitro fertilization. The father's sperm can fertilize the patient egg before the maternal genetic material is removed or after the maternal genetic material has been transferred to the donor egg. Hence, statement 1 is correct.
Mitochondrial diseases are chronic (long-term), genetic, often inherited disorders that occur when mitochondria fail to produce enough energy for the body to function properly. As the mitochondrial genome is inherited exclusively from the mother, the child inherits mitochondrial diseases entirely from mother and not from father. Hence, statement 2 is correct.
Therefore, option (c) is the correct answer.
Q4: Bollgard I and Bollgard II technologies are mentioned in the context of.. (a) clonal propagation of crop plants (b) developing genetically modified crop plants (c) production of plant growth substances (d) production of biofertilizers
Solution:
Ans: (b) Bollgard I - Bt cotton (single-gene technology) is first biotech crop technology approved for commercialization in India in 2002, followed by Bollgard II - double-gene technology in mid-2006, by the Genetic Engineering Approval Committee, the Indian regulatory body for biotech crops. Therefore, option (b) is the correct answer.
Q5: In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following?
Area of the hole in the lid
Temperature of the flame
Weight of the lid
Select the correct answer using the code given below. (a) 1 and 2 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3
Solution:
Ans: (d)
The Charles law states that pressure (P), volume (V) and temperature (T) is equal to a constant K i.e. PVT = k.
From the above-given equation, we can infer that temperature is dependent on pressure and volume. Pressure in the cooker depends on the area of the hole in the lid, the bigger the hole in the lid, the lesser will be the pressure inside the cooker and hence temperature will be affected. Hence, 1 is correct.
The more is the temperature of the flame the more will be the temperature inside the cooker. Hence, 2 is correct.
The weight of the lid has a direct connection in relation to maintaining enough pressure in the lid, heat release and heat-storing inside the cooker and hence can be linked with the temperature inside the cooker. Hence, 3 is correct.
Therefore, option (d) is the correct answer.
Q6: Consider the following:
Bacteria
Fungi
Virus
Which of the above can be cultured in an artificial/synthetic medium? (a) 1 and 2 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3
Solution:
Ans: (a) Bacteria and Fungi can be cultured in an artificial/synthetic medium. Whereas viruses require a living host cell for replication. Infected host cells (eukaryotic or prokaryotic) can be cultured and grown, and then the growth medium can be harvested as a source of the virus. Hence, 1 and 2 are correct and 3 is not correct. Therefore, option (a) is the correct answer.
Q7: Consider the following statements:
Adenoviruses have single-stranded DNA genomes whereas retroviruses have double- stranded DNA genomes.
Common cold is sometimes caused by an adenovirus whereas AIDS is caused by a retrovirus.
Which of the statements given above is/are correct? (a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2
Solution:
Ans: (b)
Adenovirus is a type of virus that has no envelope whereas retroviruses are characterized as enveloped viruses. Adenoviruses have double-stranded linear DNA and are associated with two major core proteins. A retrovirus is a virus that uses RNA as its genetic material. When a retrovirus infects a cell, it makes a DNA copy of its genome that is inserted into the DNA of the host cell. Hence, statement 1 is not correct.
Adenoviruses are common viruses that cause a range of illnesses. They can cause cold-like symptoms, fever, sore throat, bronchitis, pneumonia, diarrhoea, and pink eye (conjunctivitis). Whereas, retroviruses can cause several human diseases such as some forms of cancer and AIDS. Hence, statement 2 is correct.
Therefore, option (b) is the correct answer.
Q8: Water can dissolve more substances than any other liquid because (a) it is dipolar in nature (b) it is a good conductor of heat (c) it has a high value of specific heat (d) it has an oxide of hydrogen
Solution:
Ans: (a) An important feature of the water molecule is its polar nature i.e., its polarity allows water to dissolve other polar substances very easily. Therefore, option (a) is the correct answer.
Q9: With reference to street lighting, how do sodium lamps differ from LED lamps?
Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps.
As street lights, sodium lamps have a longer lifespan than LED lamps.
The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street lighting.
Select the correct answer using the code given below. (a) 3 only (b) 2 only (c) 1 and 3 only (d) 1, 2 and 3
Solution:
Ans: (c)
LEDs emit light for 180 degrees. This is typically an advantage because the light is usually desired over a target area (rather than all 360 degrees around the bulb).
Whereas Sodium lamps emit light omnidirectionally. This means they emit light for 360 degrees, requiring fixture housings or reflectors to direct a large portion of the emissions to the desired target area. Hence, 1 is correct.
LEDs have an extremely long lifespan relative to every other lighting technology. New LEDs can last 50,000 to 100,000 hours or more. Hence, 2 is not correct.
Sodium lamps have the worst colour rendering of any bulb. They produce a dark yellow glow which is generally a very low-quality light. LEDs are available in a wide range of colour temperatures that generally span from 2200K-6000K (ranging from "warm" yellow to light or "cool" blue). Hence, 3 is correct.
Therefore, option (c) is the correct answer.
Q10: The term 'ACE2' is talked about in the context of.. (a) genes introduced in the genetically modified plants (b) development of India's own satellite navigation system (c) radio collars for wildlife tracking (d) spread of viral diseases
Solution:
Ans: (d)
'ACE2' is a proteinaceous enzyme on the surface of many cell types that stands for Angiotensin Convertase Enzyme-2. It is an enzyme that generates small proteins by cutting up the larger protein angiotensinogen that then goes on to regulate functions in the cell.
Using the spike-like protein on its surface, the SARS-CoV-2 virus binds to ACE2 like a key being inserted into a lock - prior to entry and infection of cells. Hence, ACE2 acts as a cellular doorway or a receptor for the virus that causes COVID-19.
Therefore, option (d) is the correct answer.
Q11: Bisphenol A (BPA), a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics? (a) Low-density polyethylene (b) Polycarbonate (c) Polyethylene terephthalate (d) Polyvinyl chloride
Solution:
Ans: (b) Bisphenol A (BPA) is a chemical produced in large quantities, primarily for the use in the production of polycarbonate plastics and epoxy resins. Therefore, option (b) is the correct answer.
Q12: 'Triclosan', considered harmful when exposed to high levels for a long time, is most likely present in which of the following? (a) Food preservatives (b) Fruit-ripening substances (c) Reused plastic containers (d) Toiletries
Solution:
Ans: (d) Triclosan is an ingredient added to many consumer products intended to reduce or prevent bacterial contamination. It is added to toiletries like antibacterial soaps and body washes, toothpaste, and some cosmetics. Therefore, option (d) is the correct answer.
Q13: Which one of the following is a reason why astronomical distances are measured in light-years? (a) Distances among stellar bodies do not change. (b) Gravity of stellar bodies does not change. (c) Light always travels in a straight line. (d) Speed of light is always the same.
Solution:
Ans: (d)
A light-year is the distance a beam of light travels in a single Earth year, or 6 trillion miles (9.7 trillion kilometers).
The reason for using light years to measure distance in space is because throughout the universe, light travels at exactly the same speed.
FAQs on UPSC Prelims Previous Year Questions 2021: Science & Technology
1. What are the important topics to study in Science & Technology for UPSC Prelims?
Ans. Some important topics to study in Science & Technology for UPSC Prelims include basics of physics, chemistry, and biology, latest developments in space technology, information technology, biotechnology, nanotechnology, robotics, and artificial intelligence.
2. Can you provide some tips to effectively prepare for the Science & Technology section of UPSC Prelims?
Ans. Yes, here are some tips to effectively prepare for the Science & Technology section of UPSC Prelims: 1. Start by understanding the basic concepts of physics, chemistry, and biology. 2. Stay updated with the latest developments in science and technology through newspapers, magazines, and online resources. 3. Make use of diagrams, flowcharts, and mind maps to understand complex topics. 4. Solve previous year question papers and take mock tests to improve your understanding and time management skills. 5. Focus on understanding the application of science and technology in daily life and its impact on society.
3. What are the recent advancements in space technology that can be asked in UPSC Prelims?
Ans. Some recent advancements in space technology that can be asked in UPSC Prelims include: 1. Mars Mission: The successful missions to Mars by various space agencies, such as NASA's Perseverance rover and the UAE's Hope probe. 2. Chandrayaan-2: India's second lunar exploration mission, which included a lander, a rover, and an orbiter. 3. Satellite Communication: Advancements in satellite communication technology, including the deployment of mega-constellations like SpaceX's Starlink. 4. Space Tourism: The emerging trend of private companies offering space tourism experiences, such as Virgin Galactic and Blue Origin. 5. Space Debris Management: Efforts to tackle the growing problem of space debris through techniques like active debris removal and space debris tracking systems.
4. How is biotechnology relevant for the UPSC Prelims examination?
Ans. Biotechnology is relevant for the UPSC Prelims examination as it is an important field of science and technology with various applications. Some key areas to focus on include: 1. Genetic Engineering: Understanding the concepts and applications of genetic engineering, including genetically modified organisms (GMOs) and gene editing techniques like CRISPR-Cas9. 2. Biomedical Technology: Knowledge of biomedical technologies like gene therapy, stem cell research, and tissue engineering. 3. Agriculture and Biotechnology: The role of biotechnology in improving agricultural practices, such as genetically modified crops, biofertilizers, and biopesticides. 4. Environmental Biotechnology: Understanding how biotechnology can be used for environmental conservation, waste management, and pollution control. 5. Healthcare and Diagnostics: Knowledge of biotechnological tools and techniques used in healthcare, such as DNA sequencing, polymerase chain reaction (PCR), and biopharmaceuticals.
5. What is the significance of robotics and artificial intelligence in the field of Science & Technology?
Ans. Robotics and artificial intelligence (AI) have significant implications in the field of Science & Technology. Here are some points highlighting their significance: 1. Automation: Robotics and AI technologies enable automation in various industries, leading to increased efficiency and productivity. 2. Healthcare: Robotics and AI are used in medical surgeries, diagnosis, and rehabilitation, improving healthcare outcomes. 3. Space Exploration: Robots and AI systems are used in space exploration missions, assisting astronauts and performing tasks in harsh environments. 4. Manufacturing: Robotics and AI play a crucial role in modern manufacturing processes, leading to precision, speed, and cost-effectiveness. 5. Future Applications: Robotics and AI have the potential to revolutionize various sectors, including transportation, agriculture, education, and entertainment.
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