Previous Year UPSC Questions

Explanation

Thunder is caused by lightning. When a lightning bolt travels through the air, it heats the air to an extremely high temperature (up to 30,000 Kelvin). This sudden heating causes the air to expand explosively, creating a shockwave that we hear as thunder. It is not caused by the meeting of clouds, the separation of clouds, or the upward movement of air and water particles.

Statement 1 is incorrect: Thunder is not caused by the meeting of clouds. Cumulonimbus clouds are indeed responsible for thunderstorms, but thunder itself results from the rapid heating and expansion of air due to lightning, not the merging of clouds.

Statement 2 is incorrect: Lightning occurs due to electrical dis-charge within or between clouds and the ground. Thunder results from the sudden expansion of air due to the intense heat of lightning, not from nimbus cloud separation.

Statement 3 is incorrect: While violent air and water particle movements occur within cumulonimbus clouds during a thunderstorm, they do not directly produce thunder. The updrafts and downdrafts determine storm intensity but are not responsible for the sound of thunder.

Explanation

Muscle contraction is a complex physiological process regulated by nerve impulses and the interaction of muscle proteins actin and myosin. Key minerals involved in muscle contraction include: Calcium (Ca), Sodium (Na), Potassium (K), Magnesium (Mg).

Option 1 is correct: Calcium ions are essential for muscle contraction. They bind to regulatory proteins within muscle fibers, facilitating the interaction between actin and myosin, the proteins responsible for muscle contraction. Without adequate calcium, muscles cannot contract properly.

Option 2 is correct: Iron helps to support continued functioning of the muscle by supporting energy production in your muscle cells, so that muscle fibres always have the energy they need to contract properly. Also supports healthy circulation so that muscles can receive additional oxygen from the bloodstream and helps muscles store oxygen to power muscle contractions.

Option 3 is correct: Sodium is crucial for initiating and transmitting nerve impulses that lead to muscle contraction. It helps generate action potentials in nerve cells, which then stimulate muscle fibers to contract. Proper sodium levels are necessary for effective communication between the nervous system and muscles.

Explanation

The Bhakti movement was a devotional reform movement in India that emphasized personal devotion to a chosen deity, transcending ritualism and caste distinctions. It gained momentum through saints like Kabir, Ramanuja, Mirabai, Tulsidas, Alvars, and Nayanars, who spread the message of love and surrender to God.

Option (b) is correct: Guru Nanak was preaching during the time when the Lodi dynasty fell and Babur took over. He emphasized the oneness of God, equality of all people, selfless service, and devotion to truth, transcending religious divisions. While Dadu Dayal was born after the fall of the Lodi dynasty and was active during the latter part of the 16th century, so he was not preaching when Babur took over. Tyagaraja, on the other hand, lived in the 18th-19th century, much later than the fall of the Lodi dynasty.

Explanation

The Indian schools of orthodox philosophy (stika) include Nyaya, Vaisheshika, Sankhya, Yoga, Mimamsa, and Vedanta, all of which accept the authority of the Vedas. These schools emphasize reasoning, metaphysical principles, and the pursuit of liberation through knowledge, ethics, and meditation.

Statement 1 is incorrect: While Samkhya accepts rebirth (or samsara) and acknowledges that the soul’s entanglement with Prakriti results in repeated cycles of reincarnation, it does not emphasize karma in the same way as the systems that directly teach the law of cause and effect leading to future rebirths. Samkhya philosophy is dualistic and not monistic because it has two entities, Purush (spirit) and Prakriti (nature).

Statement 2 is correct: Samkhya emphasizes the attainment of knowledge of the self by means of concentration and meditation. It believes that after you have ‘died’ in this life you will go through a process of rebirth where depending on your actions in your former life your status will be decided. Liberation (moksha) occurs when the Purusha realizes its distinct nature from Prakriti, ending the cycle of reincarnation.

Explanation

Yuan Chwang, the Chinese traveler, provided a detailed account of India during the 7th century, noting its thriving culture, well-organized society, and vibrant Buddhist institutions. He described India’s cities, roads, and religious life.

Statement 1 is incorrect: Roads and river routes were not completely robbery-free. He described the condition of roads as generally safe, but he also noted that there were occasional dangers and robberies on certain routes. Hiuen-Tsang himself was looted a couple of times.

Statement 2 is correct: Criminal law was very severe. He mentioned that the judicial system in India involved ordeals by fire, water, and poison as a way to determine guilt or innocence.

Statement 3 is correct: Duties were to be paid at trade barriers without fail. It was a source of income for the kingdom.

Explanation

The Bhakti movement began to spread across eastern and northern India from the 15th century. The movement’s central idea was love, devotion, and the pursuit of equality. Prominent Bhakti saints such as Ramanuja, Chaitanya, Jaidev, Kabir, and Ramanand emphasized the unity of God. Guru Nanak was born in India during the period 1469-1539. Babur defeated Ibrahim Lodhi in the First battle of Panipat in 1526. Therefore, when Babur was strengthening the Mughal dynasty in India Guru Nanak was preaching Sikhism in India. Tyagaraja, a Carnatic music composer was born in 1767 and Daddu Dayal was a poet-saint of Gujrat born in 1544. These events do not match with the timeline of Battle of Panipat when the Lodi dynasty fell.

Explanation

Viruses are microscopic infectious agents that require a host cell to reproduce. They consist of genetic material (DNA or RNA) surrounded by a protein coat (capsid). They can cause a wide range of diseases in humans, animals, and plants.

Statement 1 is correct: Viruses are obligate intracellular parasites and lack the metabolic machinery, including enzymes, to generate energy. They depend entirely on their host cells for energy and replication.

Statement 2 is incorrect: Viruses cannot replicate or survive in synthetic media alone. They require living host cells for replication. Common methods of culturing viruses include using cell cultures, embryonated eggs, or live animals.

Statement 3 is incorrect:

While some viruses are transmitted through biological vectors (e.g., mosquitoes for dengue), many are transmitted by other means such as: Respiratory droplets (e.g., influenza virus), Direct contact (e.g., herpes simplex virus), Fomites (e.g., contaminated surfaces).

Explanation

Tattoos may cause diseases because tattoo instruments come in contact with blood and bodily fluids if the instruments are used on more than one person without being sterilised. However, tattoo-related infections are uncommon in sterile, contemporary tattoo parlours using single-use needles. Hepatitis B is a bloodborne infection caused by the Hepatitis B virus (HBV) and is spread through contact with infected blood or bodily fluids. Unsafe tattooing practices, such as using unsterilized needles or contaminated ink, can easily transmit Hepatitis B. Studies show that Hepatitis B has a significantly high transmission risk through needlestick injuries or exposure to infected blood. HIV is transmitted through contact with infected blood, semen, vaginal fluids, or breast milk. Though the risk of HIV transmission through tattooing is lower compared to Hepatitis B, it exists if contaminated needles are used. Chikungunya is primarily transmitted through the bite of infected Aedes mosquitoes and is not spread through blood or contaminated instruments.

Explanation

The Indian Statutory Commission, commonly referred to as the Simon Commission under the chairmanship of Sir John Simon arrived in British India in 1928. The Simon Commission originated as a result of the Government of India Act, 1919 (Montagu-Chelmsford Reforms), which introduced Dyarchy in provinces. The Act had a provision that after ten years, its impact would be reviewed to decide further constitutional reforms. It was appointed by the British government to assess India’s constitutional development and recommend constitutional reforms. The main reason behind the agitation against the Simon Commission was that there were no Indian members of the panel and only seven British members of the British Parliament. This was viewed as racist and colonialist.

Explanation

In Buddhist architecture, a chaitya is a prayer hall or sanctuary, typically containing a stupa (a mound-like structure that houses relics of the Buddha). Chaityas were places of worship, where Buddhist communities gathered for prayers, rituals, and meditation. These structures often have a barrel-vaulted roof and a central nave leading to the stupa at the far end. A vihara is a monastic dwelling or residence for monks. It usually consists of a series of cells or rooms surrounding a central courtyard, where monks lived, meditated, and studied. Viharas were intended for residential purposes, as opposed to chaityas, which were for communal worship. They can be found in Ajanta Caves, Karle Caves, etc.