UPSC Prelims 2023 Analysis

Explanation

The Wolbachia method is a biological method that utilises the Wolbachia bacteria to control the spread of mosquito-borne diseases, particularly dengue fever. Method

• Wolbachia naturally infects some insect species, but not Aedes aegypti mosquitoes, the primary vector for dengue fever transmission. Scientists introduce Wolbachia into Aedes aegypti populations.  Wolbachia reduces the ability of these mosquitoes to transmit dengue virus. 

• As Wolbachia spreads through the mosquito population, it can significantly reduce the incidence of dengue fever. 

• This method offers a natural and sustainable approach to controlling dengue fever, a major public health concern in tropical and subtropical regions.

Explanation

• Carbon fibres are highly valued for their unique properties like strength, lightness, and stiffness. They are widely used in the manufacturing of various components in automobiles and aircraft to reduce weight and improve performance. 

• Carbon Fiber Recycling: While traditional carbon fibre recycling methods were limited, advancements are being made in this field. Here are some possibilities 

1. Mechanical recycling - This process breaks down carbon fibres into smaller pieces for use in applications where their original form is not necessary. 

2. Chemical recycling -This method dissolves the resin holding the fibres together, potentially allowing the extraction of reusable carbon fibres. 

3. Thermal recycling- High temperatures are used to convert the resin into usable materials while recovering the carbon fibres. 

• These recycling technologies are still evolving, but they offer a more sustainable approach to using carbon fibres. Hence, statement 2 is incorrect.

Explanation

 * Satellite navigation is based on the use of range measurements between navigational satellites and the user. Information about the satellite's coordinates is given to the user through a navigation signal. Range measurements are based on the calculation of the receiving signal time delay compared with the signals generated by the user equipment.

• Currently, there are four global systems viz., GPS from the USA, GLONASS from Russia, Galileo from the European Union, and BeiDou from China. In addition, there are two regional systems viz., NavIC from India and QZSS from Japan.

• Global navigation system caters to the users in the entire world, whereas the regional navigation system caters to the users in the limited service area.

Hence option (d) is the correct answer.

Explanation

• Statement 1 is correct: Pyrolobus fumarii, an archaeon living at 113 C in Atlantic hydrothermal vents.Pyrococcus furiosus, an archaeon which thrives at 100C, first discovered in Italy near a volcanic vent. 

• Statement 2 is correct: Psychrophiles or cryophiles (adj. psychrophilic or cryophilic) are extremophilic organisms that are capable of growth and reproduction in low temperatures, ranging from 20 C to 20 C. 

• Statement 3 is correct: Acidophiles are microorganisms that show optimal growth in highly acidic environments. These 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.

Explanation

• Neither of the statements about ballistic missiles and cruise missiles is accurate.

• Ballistic missiles: These are rocket-powered weapons that follow a high, arcing trajectory after a brief powered ascent. They travel at supersonic speeds throughout most of their flight due to inertia.

• Cruise missiles: These are jet-propelled weapons that fly at relatively low altitudes and can manoeuvre throughout their flight path. They can be subsonic, supersonic, or hypersonic depending on the design.

• Agni-V: This is a long-range intercontinental ballistic missile (ICBM) developed by India. It is not a medium-range cruise missile.

• BrahMos: This is a supersonic cruise missile jointly developed by India and Russia. It is not a solid-fueled ICBM. BrahMos uses a ramjet engine for sustained supersonic flight after a booster rocket launch.

Explanation

• Metagenomics (also referred to as environmental and community genomics) is the genomic analysis of microorganisms by direct extraction and cloning of DNA from an assemblage of microorganisms. It involves:  

  • Isolating DNA from an environmental sample, 

  • Cloning the DNA into a suitable vector, 

  • Transforming the clones into a host bacterium, 

  • And screening the resulting transformants.

• Such an approach helps in sampling an entire habitat at one go. Researchers have shown that environmental DNA (e-DNA) can potentially identify and monitor terrestrial animals. Animals shed DNA through their breath, saliva, fur, or faeces into the environment. These samples are called e-DNA.

Hence, Statement A is correct.

Explanation

• Microsatellite DNA, also known as short tandem repeats (STRs), are highly polymorphic DNA sequences that are widely used in the case of studying the evolutionary relationships among various species of fauna. 

• Microsatellite DNA analysis is a powerful tool for studying genetic diversity, population structure, and evolutionary relationships among different species of animals. 

• The variations in the number of repeated DNA sequences in microsatellites can provide insights into the genetic similarities and differences between species, which can be used to infer their evolutionary relationships.

Explanation

• Cepheids are actually stars that brighten and dim periodically, not giant clouds of dust and gas. 

• Nebulae are giant clouds of dust and gas in space, not stars that brighten and dim periodically.Thus, the first two pairs are reversed. 

• Pulsars are rapidly rotating neutron stars that are formed when massive stars exhaust their fuel and collapse. 

• So out of the 3 pairs given, only 1 pair (pair 3) is correctly matched.

Explanation

• Car Crash Detection and Airbag Deployment: Modern cars use accelerometers as part of a complex system to detect rapid deceleration that can indicate a crash. The accelerometer data, along with other sensors, triggers the airbag deployment almost instantaneously. 

• Laptop Fall Detection and Hard Drive Shut Off: Some laptops use accelerometers to detect a sudden fall or impact. This can trigger the hard drive heads to retract or park, protecting the drive from potential damage. 

• Smartphone Tilt Detection and Display Rotation: Accelerometers are widely used in smartphones to detect orientation changes (tilt). This allows the device to automatically switch the display between portrait and landscape mode depending on how you hold the phone. 

• In all these scenarios, the accelerometer detects changes in acceleration or tilt, which is then used by the system to perform the specific action.

Therefore, all three statements are correct.