Science and Technology: UPSC Previous Year Questions (Prelims)

Explanation

Indian Remote Sensing (IRS) satellites developed by the Indian Space Research Organisation (ISRO) are primarily designed for Earth observation and resource management. Their applications encompass various fields, including agriculture, water resources, urban planning, rural development, mineral prospecting, environment, forestry, ocean resources, and disaster management.

Option (a) is correct: Indian Remote Sensing satellites play a crucial role in agriculture. They provide data on crop health, soil conditions and vegetation cover which are essential for assessing crop productivity. The satellites capture multispectral and hyperspectral images that help in monitoring crop growth, predicting yields, and identifying areas affected by drought or pests. IRS satellites are instrumental in identifying potential groundwater resources. They use remote sensing techniques to map geological features, soil moisture, and vegetation patterns that indicate the presence of groundwater. ISRO’s Bhuvan portal provides satellite-based groundwater prospect maps. IRS satellites are used in mineral exploration by providing detailed images of the Earth’s surface which help geologists identify mineral-rich areas based on spectral signatures of rocks and soils. This reduces the need for extensive ground surveys. The Geological Survey of India (GSI) collaborates with ISRO to use remote sensing data for mineral exploration. IRS satellites are not designed for telecommunications. Telecommunications satellites such as the Indian National Satellite (INSAT) series are used for communication purposes including television broadcasting, internet services, and telephony. Traffic studies typically rely on data from ground-based sensors, GPS and other real-time monitoring systems. While satellites can provide broad-scale urban planning data but IRS satellites are not specifically designed for traffic management.

Explanation

The Goldilocks Zone, or habitable zone, refers to the region around a star where conditions are "just right" for liquid water to exist on a planet’s surface--a key factor for life as we know it. This zone depends on the star’s size and temperature. Earth lies within the Sun’s Goldilocks Zone, enabling its rich biodiversity. Exoplanets within their star’s habitable zones, such as Kepler-452b, are prime candidates in the search for extraterrestrial life.

Explanation

Statement 1 is correct: In a hydrogen fuel cell, hydrogen (H₂) reacts with oxygen (O₂) from the air in an electrochemical reaction. This process generates electricity along with water (H₂O) and heat as by-products. Since no harmful emissions are released, this is considered a clean energy technology.

Statement 2 is incorrect: Fuel cells are highly adaptable and can be designed for various applications, ranging from powering large buildings and vehicles to smaller portable devices such as laptops. Proton Exchange Membrane Fuel Cells (PEMFCs) are particularly suitable for portable devices due to their compact size and efficiency.

Statement 3 is incorrect: Fuel cells generate electricity in the form of Direct Current (DC). However, many applications require Alternating Current (AC) to operate and thus an inverter is typically used to convert the DC produced by the fuel cell into AC.

Explanation

Statement 1 is correct: The National Innovation Foundation-India (NIF) was established in 2000 with the support of the Department of Science and Technology (DST), Government of India. In 2010 NIF became an autonomous body under the DST.

Statement 2 is incorrect: NIF’s primary mission is to strengthen grassroots technological innovations and outstanding traditional knowledge in India. It focuses on scouting, supporting, and scaling up innovations developed by individuals and local communities at the grassroots level rather than concentrating on advanced scientific research in collaboration with foreign institutions. Its primary goal is to support and scale up innovations by common people, especially in rural areas.

Explanation

Pair 1 is correctly matched: Scurvy is caused by a deficiency of Vitamin C (ascorbic acid). It leads to symptoms like bleeding gums, bruising, fatigue, and poor wound healing.

Pair 2 is correctly matched: Rickets occurs due to Vitamin D deficiency, which impairs calcium absorption, leading to soft and weak bones in children. In adults, it can lead to osteomalacia.

Pair 3 is incorrectly matched: Night blindness is caused by a deficiency of Vitamin A, not Vitamin E. Vitamin A is crucial for maintaining healthy vision, particularly in low-light conditions. Vitamin E deficiency, on the other hand, may lead to nerve and muscle damage or immune system issues.

Explanation

Diphtheria has not been eradicated in India. It remains a public health concern, with cases still reported annually. It is a bacterial disease caused by Corynebacterium diphtheriae. It primarily affects the respiratory system, causing symptoms such as a sore throat, fever, and difficulty breathing. A characteristic thick gray membrane forms on the throat and tonsils in severe cases. Diphtheria spreads through respiratory droplets or contact with contaminated objects. It is preventable through the DPT (Diphtheria-Pertussis-Tetanus) vaccine, which is part of India’s Universal Immunization Programme (UIP). Chickenpox has not been eradicated in India. It is a common infectious disease, particularly among children, and continues to occur throughout the country. It is caused by the Varicella-zoster virus (VZV), a highly contagious virus that spreads through respiratory droplets or direct contact with blisters. Symptoms include an itchy rash with red spots or blisters, fever, and fatigue. Following extensive surveillance and immunization campaigns, the World Health Organization (WHO) declared India free of smallpox in 1977. It is caused by the Variola virus, was one of the deadliest diseases in history, with a high mortality rate of 30%. It presented with symptoms like high fever, severe headache, and distinctive pus-filled blisters. Smallpox spread through direct contact with infected individuals or contaminated objects.

Explanation

Biometrics identification is a form of identification and access control. Biometric identifiers are the distinct, measurable characteristics used to label individuals. Physiological characteristics are distinguished from behavioural traits when classifying biometric identifiers. Fingerprint, palm veins, face recognition, DNA, palm print, hand geometry, iris recognition, retina, and odour/scent are examples of physiological biometric identifiers. Visible and near - infrared light used captures and analyzes the unique patterns in the colored part of the eye surrounding the pupil. It is a highly reliable and accurate biometric method used in security and access control systems. It is used in Aadhaar biometric identification in India. Retinal scanning maps the unique pattern of blood vessels in the retina at the back of the eye. This method is highly accurate but less commonly used due to its intrusive nature, requiring the user to position their eye close to the scanner. Voice recognition analyzes the unique characteristics of an individual’s voice, such as tone, pitch, and rhythm, for authentication. It is widely used in phone-based security systems and other applications requiring remote verification.

Explanation

Pair 1 is incorrectly matched: The Cassini-Huygens mission was a collaborative project between NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to study Saturn and its moons, not Venus. Huygens probe landed on Titan, Saturn’s largest moon in 2005 and provided valuable data about its atmosphere and surface.

Pair 2 is correctly matched: The Messenger (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft was a NASA mission designed to study Mercury. It orbited Mercury and mapped its surface, studying its geology, and investigating its magnetic field and exosphere.

Pair 3 is correctly matched: The Voyager 1 and Voyager 2 spacecraft were launched by NASA in 1977 to explore the outer planets of the solar system. Voyager 1 flew by Jupiter and Saturn, providing detailed images and data about these planets and their moons. Voyager 2 visited all four outer planets:

Jupiter, Saturn, Uranus, and Neptune. The spacecraft are now in interstellar space, continuing to transmit data about the heliosphere and beyond.

Explanation

Option (b) is correct: Cluster bean commonly known as guar has traditionally been utilized in India as a vegetable and animal feed. Guar gum is widely used in the oil and gas industry particularly in hydraulic fracturing (fracking) for shale gas extraction. It acts as a thickening agent in fracking fluids, helping to carry proppants (like sand) into fractures in the shale rock to keep them open and allow gas to flow. India is one of the largest producers of guar in the world and the demand for guar gum surged due to its use in shale gas extraction especially in the United States.

Option (a),(c) and (d) are incorrect:

Guar seeds are primarily known for their gum content and not oil. It has applications in various industries (food, pharmaceuticals, textiles, etc.) but there is no widespread use of guar seed oil in the manufacture of biodegradable plastics. Traditionally guar leaves have been consumed as a vegetable but their medicinal properties particularly as antihistamines is not well-documented. Guar seeds are not a significant source of biodiesel. It is not commercially significant or widely recognized as a high-quality biodiesel source.

Explanation

The Agni-IV is an intermediate-range ballistic missile developed by India’s Defence Research and Development Organisation (DRDO)

Statement 1 is correct: The Agni-IV is designed as a surface-to-surface missile, capable of being launched from the ground to strike terrestrial targets. It enhances India’s strategic strike capabilities. Statements 2 is incorrect: The Agni-IV utilizes a two-stage solid propellant system, not liquid propellant. Solid propellants offer advantages such as easier handling and longer storage life, which are beneficial for ballistic missiles. Statements 3 is incorrect: The Agni-IV has a range of around 4,000 km and is capable of carrying a payload of up to one tonne, including nuclear warheads. A range of 7,500 km would classify the missile as an intercontinental ballistic missile (ICBM), but the Agni-IV is categorized as an intermediate-range ballistic missile (IRBM).