UPSC Prelims Previous Year Questions 2023: Science & Technology | Science & Technology for UPSC CSE PDF Download

Ans: (c)

• Hyperthermophilic (‘superheat-loving’) bacteria and archaea are found within high- temperature environments. Hence, statement 1 is correct.
• Microorganisms live in every part of the biosphere, and some of them are even capable of growing at low temperatures, including those below the freezing point. These microorganisms live in the sea or in high mountains. Hence, statement 2 is correct.
• Acidophiles are microorganisms that show optimal growth in highly acidic environments. They are of two types. The extreme acidophiles dwell in environments with a pH value <3, and moderate acidophiles grow optimally in conditions having pH values ranging between 3 and 5. Hence, statement 3 is correct.

Ans: (a)

Wolbachia are natural bacteria present in up to 60% of insect species, including some mosquitoes. Wolbachia bacteria cannot make people or animals (for example, fish, birds, pets) sick.

• For many years, scientists have been studying Wolbachia, looking for ways to use it to potentially control the mosquitoes that transmit human viruses.

The World Mosquito Program’s Wolbachia Method:

• The WMP's field teams release male and female Aedes aegypti mosquitoes with Wolbachia over a number of weeks. These mosquitoes then breed with the wild mosquito population. Over time, the percentage of mosquitoes carrying Wolbachia grows until it remains high without the need for further releases.
• Mosquitoes with Wolbachia have a reduced ability to transmit viruses to people, decreasing the risk of Zika, dengue, chikungunya and yellow fever outbreaks.

Hence, option (a) is correct.

Ans: (a)

• Metagenomics is the study of the structure and function of entire nucleotide sequences isolated and analysed from all the organisms (typically microbes) in a bulk sample.
  • Metagenomics is often used to study a specific community of microorganisms, such as those residing on human skin, in the soil or in a water sample.
• Aerial metagenomics is a scientific field that involves studying the genetic material present in the air, specifically the DNA and RNA of microorganisms suspended in the atmosphere.
  • It focuses on the analysis of the microbial communities or microbiomes found in the air samples collected from various environments such as outdoor air, indoor air, and airborne particles.

Hence, option A is correct.

Ans: (a,d)

• Microsatellite, as related to genomics, refers to a short segment of DNA, usually one to six or more base pairs in length, that is repeated multiple times in succession at a particular genomic location.
• These DNA sequences are typically non-coding.
• They are useful in providing valuable insights into disease prevalence, the discovery of new genes related to rare diseases, improved diagnostic methods, and the development of novel drugs for these diseases.

Hence, option (a/d) is correct.

Ans: (c)

Functions of Accelerometer:

• The accelerometer detects signals that are used to identify major vehicle crash/collisions. Hence, statement 1 is correct.
• The application of accelerometers extends to multiple disciplines, both academic and consumer-driven.
  • For example, accelerometers in laptops protect hard drives from damage. If the laptop were to suddenly drop while in use, the accelerometer would detect the sudden free fall and immediately turn off the hard drive to avoid hitting the reading heads into the hard drive platter. Hence, statement 2 is correct.
• Accelerometers allow the user to understand the surroundings of an item better.
  • For example, smartphones rotate their display between portrait and landscape mode depending on how you tilt the phone. Hence, statement 3 is correct.

Ans: (b)
Role of Biofilters in Recirculating Aquaculture System (RAS):

• RAS biofilters act to remove nitrogenous waste byproducts generated by fish protein catabolism and oxidation processes. Hence, statement 1 is correct.
• RAS typically employ a biofilter to control ammonia levels produced as a byproduct of fish protein catabolism.
  • Ammonia is removed from an aquarium system through the use of a biofilter. The biofilter provides a substrate on which nitrifying bacteria grow. These nitrifying bacteria consume ammonia and produce nitrite, which is also toxic to fish.
  • Other nitrifying bacteria in the biofilter consume nitrite and produce nitrate. Hence, statement 2 is correct.
• The biofilter system reduces the concentration of nitrite, nitrate, phosphorus, and ammonium ions from the synthetic water. Hence, statement 3 is not correct.

Ans: (d)

• Cepheids, also called Cepheid Variables, are stars which brigthen and dim periodically. This behavior allows them to be used as cosmic yardsticks out to distances of a few tens of millions of light-years. Hence, pair 1 is not correctly matched.
• Cepheids, also called Cepheid Variables, are stars which brigthen and dim periodically. This behavior allows them to be used as cosmic yardsticks out to distances of a few tens of millions of light-years.

• A nebula is a giant cloud of dust and gas in space. Some nebulae (more than one nebula) come from the gas and dust thrown out by the explosion of a dying star, such as a supernova. Hence, pair 2 is not correctly matched.
• Pulsars are rotating neutron stars observed to have pulses of radiation at very regular intervals that typically range from milliseconds to seconds. Hence, pair 3 is not correctly matched.

Ans: (d)
Cruise missiles are jet-propelled at subsonic speeds throughout their flights, while ballistic missiles are rocket-powered only in the initial (boost) phase of flight, after which they follow an arcing trajectory to the target. Hence, statement 1 is not correct. Agni V is India’s long-range surface-to-surface ballistic missile, which can hit a target with a precision that is 5,000 km away. The BrahMos is a supersonic cruise missile, developed by the joint Russian-Indian BrahMos Aerospace company. Hence, statement 2 is not correct.

Ans: (c)

Green hydrogen is a type of hydrogen that is produced through the electrolysis of water using renewable energy sources such as solar or wind power. Green hydrogen can be used directly as a fuel for internal combustion. Hence, statement 1 is correct.

• Hydrogen produced through clean pathways can be injected into natural gas pipelines, and the resulting blends can be used to generate heat and power with lower emissions than using natural gas alone. Hence, statement 2 is correct.
• Hydrogen can be used in two kinds of vehicles: those with internal combustion engines (ICEs) and those with fuel cells. For example, Germany’s hydrogen-powered passenger train. Hence, statement 3 is correct.