Previous Year UPSC Questions

Explanation

An accelerometer is an electromechanical device used to measure acceleration forces. These forces may be static like the continuous force of gravity or dynamic force to sense movement or vibrations.

Statement 1 is correct: Upon a collision, the crash sensor, typically an accelerometer, transmits a signal to the airbag control unit to deploy the airbags almost immediately.

Statement 2 is correct: 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.

Statement 3 is correct: Accelerometer is used in smartphones as it detects the rotation of their display between portrait and landscape mode depending on the tilt of the phone.

Explanation

Statement 1 is correct: The use of biofilters to remove toxins from wastewater and waste gases has advanced in recent decades. In order to remove contaminants from a fluid stream, biofilters fix microorganisms to an inorganic/organic medium (carrier), which has the ability to break down a wide range of chemicals. By removing uneaten fish feed, they additionally perform waste treatment.

Statement 2 is correct: By constructing a biofilter correctly, it is possible to regulate ammonia and nitrite concentrations at levels safe for fish. Through the biofiltration process, ammonia nitrogen is converted into nitrite nitrogen, which is subsequently transformed into less harmful nitrate nitrogen, ensuring a conducive environment for fish.

Statement 3 is incorrect: Biofilters do not increase phosphorus as a nutrient for fish in water. Phosphorus (P) is actually removed by biofilters to prevent eutrophication in waters.

Explanation

Green hydrogen is a renewable energy source that, unlike coal and oil, solely releases water vapour and leaves no residue in the air.

Statement 1 is correct: Hydrogen, a zero-carbon fuel, can be used to power automobiles through both hydrogen internal combustion engines and hydrogen fuel cells.Hydrogen engines utilize hydrogen in an internal combustion engine, operating similarly to the way gasoline powers conventional engines.

Statement 2 is correct: Clean hydrogen may be created and injected into natural gas pipelines to create blends that can be utilised to provide heat and power with fewer emissions than just natural gas.

Statement 3 is correct: A fuel cell harnesses the chemical energy of green hydrogen or alternative fuels to generate electricity in a clean and efficient manner. When hydrogen serves as the fuel, the sole byproducts produced are electricity, water, and heat.

Explanation

Statement 1 is incorrect: The State Government will establish a Community Reserve management committee, which will be in charge of conserving, maintaining, and overseeing the community reserve in accordance with Section 36 D of the Wild-life Protection Act (WLPA). The committee will choose a chairman who will serve as the community reserve’s Honorary Wild Life Warden.

Statement 2 is correct: Community Reserves are designated to protect wildlife and biodiversity. Under the Wildlife Protection Act, 1972 hunting is strictly prohibited in all protected areas including Community Reserves. Section 9 of the Act prohibits hunting of wild animals listed in Schedules I, II, III, and IV.

Statement 3 is correct: In a Community Reserve, the collection of non-timber forest produce by the local communities is subject to the specific rules and regulations governing the Community Reserve. It may be regulated or restricted to ensure sustainable use and conservation of resources.

Statement 4 is incorrect: After a forest has been made into a community reserve, people cannot use it for agricultural practices, leave alone jhum cultivation.

Explanation

The Invasive Species Specialist Group (ISSG) is a global network of scientific and policy experts on invasive species, organised under the auspices of the Species Survival Commission (SSC) of the International Union for Conservation of Nature (IUCN). The ISSG fosters and enables the worldwide exchange of knowledge and information concerning invasive species. It also ensures the linkage between knowledge, practice, and policy to ensure that decisions are based on well-informed insights.

Explanation

Statement 1 is correct: Mushrooms possess antibacterial properties, enhance the immune system, and aid in lowering cholesterol levels. Moreover, they serve as significant reservoirs of bioactive compounds. Consequently, certain mushroom extracts are utilised to support human health and are available in the form of dietary supplements.

Statement 2 is correct: Psychoactive properties refer to substances that influence brain function, resulting in alterations in mood, awareness, cognition, emotions, or behaviour. Psilocybin is a hallucinogenic compound found in specific mushrooms commonly known as magic mushrooms.

Statement 3 is correct: In recent times, there has been a growing discovery of insecticidal compounds within mushrooms.

Statement 4 is correct: Bioluminescence refers to the generation and release of light by living organisms. Panellus stipticus stands out as one of the most luminous bioluminescent mushrooms found on our planet. The newly discovered species, designated as Roridomyces phyllostachydis found in Meghalaya, now joins the ranks of the 97 recognised types of bioluminescent fungi world- wide.

Explanation

Statement 1 is incorrect: Indian squirrels, such as the Indian Palm Squirrel, do not burrow in the ground to build nests. Instead, they construct nests in trees, crevices, or other elevated areas using materials like leaves and twigs. Burrow-making is more characteristic of rodents like rats or ground squirrels, which are not typical Indian squirrels.

Statement 2 is correct: Nuts serve as the primary food source for these creatures year-round, especially during the winter months when they are preparing for hibernation. They store nuts by burying them underground, enabling retrieval during the win-ter season.

Statement 3 is correct: Squirrels are omnivores. Their diet primarily consists of nuts and fruits, although they will also consume seeds, insects, small mammals, reptiles, eggs, and occasionally even bird chicks.

Explanation

Statement 1 is correct: The Supreme Court of India has held in several judgments - Indra Sawhney v Union of India (1992) and M Nagaraj v Union of India (2006) that the reservation policies made under Article 16(4) of the Constitution would be limited by Article 335, which provides for ‘maintenance of efficiency of administration’, while considering the claims of the Scheduled Castes (SCs) and the Scheduled Tribes (STs) in the making of appointments to public services and posts.

Statement 2 is incorrect: Article 335 mentions that the claims of Scheduled Castes (SCs) and Scheduled Tribes (STs) must be considered in appointments to services and posts, but this must be consistent with the maintenance of efficiency in administration. However, Article 335 does not define the term "efficiency of administration", leaving its interpretation to judicial and administrative discretion. This gap in interpretation was filled by a two-judge bench in the B K Pavitra (II) v Union of India (2019), as it held that ‘efficiency of administration in the affairs of the union or of a state must be defined in an inclusive sense, where diverse segments of society find representation as a true aspiration of governance by and for the people’.

Explanation

Option 1 is incorrect: Jackfruit(Artocarpus heterophyllus) is an evergreen tree native to tropical regions of Asia. It retains its foliage throughout the year unlike deciduous trees, which shed their leaves during certain seasons. The tree thrives in hot and humid climates and is known for edible fruit that grows directly from the trunk. Jackfruit trees are common in India, Bangladesh, and Southeast Asia Option 2 is correct: Mahua (Madhuca indica) is a deciduous tree found in the dry forests of Central India including parts of Madhya Pradesh, Jharkhand, and Chhattisgarh. This tree sheds its leaves during the dry season to conserve water. Mahua is culturally significant in tribal communities and its flowers are used to make a traditional alcoholic drink. The tree’s flowers are also edible and have medicinal properties.

Option 3 is correct: Teak (Tectona grandis) is one of the most valuable hardwoods in the world. It is a deciduous tree that sheds its leaves in the dry season between February and March. It is known for its durability, resistance to weathering, and ability to withstand termites which makes it highly sought after for furniture, shipbuilding, and construction.

Explanation

Option 4 is correct: The Rann of Kutch in Gujarat is an extensive marshland formed due to repeated falls in sea level. This region was a shallow part of the Arabian Sea. Over time tectonic activity and sea level changes caused the area to be-come landlocked and created a vast salt marsh. During monsoons it gets flooded and in the dry season it turns into a salty desert.

Option 1,2 and 3 are incorrect:

Bhitarkanika Mangroves is located in Odisha. These mangroves are coastal wetlands characterized by tidal waters and mangrove forests and not by repeated falls in sea level. Marakkanam Salt Pans is situated in Tamil Nadu. These are man-made salt pans used for salt production and not natural marshlands formed by sea level changes. Naupada Swamp is a freshwater wetland, not a salt marsh formed by sea level fluctuations. It is located in Andhra Pradesh.