UPSC Prelims 2025 Analysis

Explanation

Statement I: Incorrect Viruses can survive in ocean waters. In fact, marine viruses are abundant and play a crucial role in marine ecosystems by influencing microbial populations and biogeochemical cycles. They infect various marine organisms, including bacteria, algae, and other microorganisms. Research has identified diverse viral communities in ocean waters.

Statement II: Incorrect Viruses can infect bacteria. Viruses that infect bacteria are called bacteriophages (or phages). Bacteriophages are highly specific to certain bacterial hosts and are important for regulating bacterial populations. Bacteriophages are used in research and have potential applications in phage therapy to treat bacterial infections.

Statement III: Incorrect Viruses can change the cellular transcriptional activity in host cells. Viruses often manipulate the host cell's machinery, including transcriptional activity, to facilitate their own replication and survival. They can introduce viral genes or proteins that interact with the host cell's transcription factors, leading to altered gene expression patterns.

Therefore, none of the statements are correct.

Explanation

I. Cobalt: Correct Cobalt is a key component of many lithium-ion battery cathodes, such as Lithium Cobalt Oxide (LCO) and Nickel Manganese Cobalt Oxide (NMC).

II. Graphite: Incorrect Graphite is typically used as the anode material in lithium-ion batteries, not the cathode.

III. Lithium: Correct Lithium is present in the cathode material of lithium-ion batteries, such as Lithium Cobalt Oxide (LCO), Lithium Iron Phosphate (LFP), etc.

IV. Nickel: Correct Nickel is used in several cathode chemistries, such as Nickel Manganese Cobalt (NMC) and Nickel Cobalt Aluminum (NCA).

Conclusion: Cobalt, Lithium, and Nickel are commonly found in battery cathodes, but Graphite is not. Therefore, three out of the four elements listed are usually found in battery cathodes.

Explanation

Pair I: Dornier-228 : Maritime patrol aircraft — Correct The Dornier-228 is an Indian-made aircraft used by the Indian Navy and Coast Guard for maritime patrol, surveillance, and transport roles. It is indeed a maritime patrol aircraft.

Pair II: IL-76 : Supersonic combat aircraft — Incorrect The Ilyushin IL-76 is a multi-purpose, fixed-wing, four-engine turbofan strategic airlifter designed by the Soviet Union. It is primarily used for military transport, not as a supersonic combat aircraft. It is not supersonic and not a combat aircraft.

Pair III: C-17 Globemaster III : Military transport aircraft — Correct The C-17 Globemaster III is a large military transport aircraft used by the Indian Air Force for strategic and tactical airlift missions. It is correctly described as a military transport aircraft.

Therefore, only two pairs are correctly matched.

Explanation

The correct answer is (B) These are explosives in military weapons.

Here's why:

• CL-20 (also known as HNIW), HMX (Octogen), and LLM-105: These are all high-performance explosives used in various military applications. They are known for their high energy density and brisance (shattering effect).
• A. These are alternatives to hydro-fluorocarbon refrigerants: Hydrofluorocarbons (HFCs) are greenhouse gases used as refrigerants. CL-20, HMX, and LLM-105 are not related to refrigerants.
• C. These are high-energy fuels for cruise missiles: While explosives can be used in propulsion systems, these specific substances are primarily used as the explosive charge in warheads, not as fuel for propulsion.
• D. These are fuels for rocket propulsion: While some explosives can be used in specialized rocket propellants, these substances are not commonly used as primary rocket fuels.

Therefore, option B is the most accurate as it correctly identifies CL-20, HMX, and LLM-105 as explosives used in military weapons.

Explanation

I. Ethanol: Coal gasification can be used to produce syngas (a mixture of carbon monoxide and hydrogen). Syngas can then be converted into ethanol through various chemical processes like Fischer-Tropsch synthesis or other catalytic methods. So, ethanol can be produced using coal gasification.

II. Nitroglycerine: While coal gasification doesn't directly produce nitroglycerine, the syngas produced from it can be used as a feedstock to produce hydrogen and other chemicals, which are in turn used in the production of nitroglycerine. Nitroglycerine is produced by nitrating glycerol. Glycerol production can be linked to syngas via methanol production. Thus, indirectly, coal gasification supports nitroglycerine production.

III. Urea: Coal gasification can produce syngas, and from syngas, we can derive ammonia. Ammonia is a crucial ingredient in the production of urea. The Haber-Bosch process is used to convert hydrogen (derived from syngas) and nitrogen into ammonia, which then reacts with carbon dioxide (also potentially derived from syngas) to form urea.Since all three substances (Ethanol, Nitroglycerine, and Urea) can be produced using coal gasification technology (either directly or indirectly), the answer is all three.

Explanation

Statement I: Incorrect The National Rail Plan (NRP) aims to develop a 'future ready' railway system by 2030, not 2028. The plan focuses on increasing network capacity, improving freight and passenger services, and achieving sustainable operations.

Statement II: Incorrect 'Kavach' is an indigenously developed Automatic Train Protection (ATP) system. It is not developed in collaboration with Germany. It's a project under 'Make in India'.

Statement III: Correct The 'Kavach' system uses Radio Frequency Identification (RFID) tags, which are placed on the tracks in station sections. These tags help in continuously updating the train's location and speed.

Since statements I and II are incorrect, and statement III is correct, the question asks for the incorrect statements.

Explanation

Let's analyze each statement:

Statement I: Correct The Majorana 1 chip is a quantum computing chip based on Majorana zero modes, which are theorized to be more stable for quantum computation. It is expected that such chips will enable advancements in quantum computing.

Statement II: Incorrect Majorana 1 chip has not been introduced by Amazon Web Services (AWS). It is a project by Microsoft, which is working on topological quantum computing using Majorana zero modes. AWS has its own quantum computing initiatives, but Majorana 1 is not one of them.

Statement III: Correct Deep learning is indeed a subset of machine learning. Deep learning uses neural networks with many layers to model complex patterns in data, and is a part of the broader field of machine learning.

Therefore, only statements I and III are correct.

Explanation

Statement I: Correct Monoclonal antibodies are indeed man-made (synthetic) proteins. They are produced in laboratories by cloning a single type of immune cell, hence the term 'monoclonal'.

Statement II: Correct Monoclonal antibodies are designed to bind to specific antigens (such as those found on the surface of pathogens or cancer cells). By binding to these antigens, they can stimulate or modulate the immune system's response, either by marking the target for destruction or by blocking its activity.

Statement III: Correct Monoclonal antibodies have been used in the treatment of various viral infections, including the Nipah virus. For example, the monoclonal antibody m102.4 has been used on a compassionate basis to treat Nipah virus infections in humans.

Therefore, all three statements are correct.

Explanation

Statement I: Correct GAGAN (GPS-Aided Geo Augmented Navigation) is an Indian Satellite Based Augmentation System (SBAS) developed jointly by ISRO and Airports Authority of India (AAI). It is specifically designed to provide additional accuracy and integrity to GPS signals, which is essential for safety-critical applications like aviation.

Statement II: Correct By improving the accuracy, reliability, and availability of GPS signals, GAGAN enables more uniform and high-quality air traffic management. It allows for more precise navigation and landing, which enhances safety and efficiency in airspace management.

Statement III: Incorrect While GAGAN was primarily developed for aviation, its benefits are not limited to aviation alone. It can also be used in other modes of transportation such as railways, roadways, maritime, and even in agriculture, surveying, and disaster management. Thus, the statement that it will provide benefits only in aviation is incorrect.

Therefore, only statements I and II are correct.

Explanation

I. Full battery electric vehicles (BEVs): Correct These vehicles are powered solely by electricity stored in a battery pack, which is charged from an external source. They do not use an internal combustion engine and are thus considered an alternative to conventional gasoline or diesel vehicles.

II. Hydrogen fuel cell vehicles (FCEVs): Correct These vehicles use hydrogen as fuel and convert it into electricity through a fuel cell. The electricity then powers an electric motor, propelling the vehicle. The only emission is water vapor, making them a zero-emission alternative.

III. Fuel cell electric hybrid vehicles (FCEHVs): Correct These vehicles combine a fuel cell with a battery pack and an electric motor. The fuel cell provides the primary source of electricity, while the battery pack provides additional power during acceleration or hill climbing and captures energy through regenerative braking. They are also considered alternative powertrain vehicles due to their reliance on fuel cell technology.

Since all three vehicle types represent alternatives to traditional internal combustion engine vehicles, all are considered alternative (powertrain) vehicles.

Explanation

Statement I: Correct Rare earth elements (REEs) are extensively used in manufacturing flat television screens and computer monitors. Specifically:

• Europium is used to produce red phosphors in CRT monitors and LED displays
• Terbium is used for green phosphors
• Yttrium is used in red phosphors and as a host material
• Cerium is used in glass polishing and as a component in some display technologies
• Neodymium is used in speakers and magnetic components of displays

These elements are crucial for the color reproduction and functionality of modern display technologies.

Statement II: Correct Several rare earth elements exhibit phosphorescent properties:

• Europium compounds show strong red phosphorescence
• Terbium compounds exhibit green phosphorescence
• Dysprosium shows yellow phosphorescence
• Samarium exhibits orange-red phosphorescence

Phosphorescence is the property of absorbing energy and then slowly releasing it as light over time, which is different from fluorescence where light emission stops immediately when the energy source is removed.

Relationship Between Statements: Statement II directly explains Statement I. The reason rare earth elements are used in flat screens and monitors is precisely because of their phosphorescent (and fluorescent) properties. These properties allow them to:

• Convert electrical energy into visible light
• Produce specific colors when excited
• Maintain color purity and brightness
• Enable the display of images on screens

The phosphorescent properties mentioned in Statement II are the fundamental reason why these elements are valuable in display technology mentioned in Statement I.

Explanation

Statement 1: Incorrect Not all UAVs are capable of vertical landing. Vertical landing is a feature primarily associated with multirotor drones (like quadcopters) and some VTOL (Vertical Take-Off and Landing) fixed-wing aircraft. Fixed-wing UAVs typically require a runway for takeoff and landing.

Statement 2: Incorrect Automated hovering is not a standard capability across all UAV types. While many modern drones have sophisticated stabilization and GPS-assisted hovering capabilities, simpler or older UAV designs might lack this feature. Additionally, fixed-wing UAVs, by their nature, cannot hover.

Statement 3: Incorrect UAVs can utilize various power sources, not just batteries. While battery power is common, especially for smaller drones, larger UAVs can be powered by gasoline engines, hybrid systems (combining a gasoline engine with an electric generator), or even solar power. Fuel cells are also being explored as a power source for UAVs.

Explanation

I. Axiom-4: Correct Axiom-4 is a planned private crewed mission to the International Space Station (ISS) by Axiom Space. Such missions typically include micro-gravity research as a key component, with astronauts conducting various scientific experiments in the micro-gravity environment of the ISS.

II. SpaDeX: Correct SpaDeX (Space Docking Experiment) is an Indian mission by ISRO aimed at demonstrating autonomous docking technology. While its primary goal is technology demonstration, such missions often include micro-gravity research and experiments, as the environment is suitable for such studies.

III. Gaganyaan: Correct Gaganyaan is India's first human spaceflight mission. One of its objectives is to encourage and support micro-gravity research by allowing Indian scientists to conduct experiments in the micro-gravity environment of space.

Therefore, all three missions encourage and support micro-gravity research.