Science and Technology: UPSC Previous Year Questions (Prelims)

Explanation

Oceansat-2, launched by ISRO in 2009, is an Earth observation satellite designed to study oceanic and atmospheric conditions. It supports applications like ocean forecasting, fishing zone mapping, and monitoring coastal and atmospheric parameters.

Statement 1 is correct: Oceansat-2 is equipped with sensors such as the Scatterometer and Ocean Color Monitor (OCM), which help assess atmospheric parameters like water vapour content.

Statement 2 is correct: By measuring sea surface winds and temperatures, the satellite is capable of understanding and predicting monsoon dynamics, which are closely tied to oceanic and atmospheric interactions.

Statement 3 is correct: The Ocean Color Monitor onboard can detect chlorophyll concentrations, sediment levels, and other indicators of water quality, helping monitor and assess pollution in coastal regions effectively.

Explanation

Bhuvan (means Earth in Sanskrit) is a Geoportal of ISRO, to evince the Indian Earth Observation capabilities from the Indian Remote Sensing (IRS) series of satellites. It is an interactive versatile Earth-Browser which showcases multi-sensor, mutli-platform and multitemporal images with capabilities to overlay thematic information along with near real-time information from Automatic Weather Stations (AWS), Potential Fishing Zone (PFZ) information, disaster support related information like forest fire alerts, periodic agricultural drought assessment etc. Bhuvan provides 2D/3D imaging and visualization of India’s geographic data. It allows users to access and analyze spatial information, similar to Google Earth, but with a focus on Indian data and applications such as urban planning, agriculture, and disaster management. But due to security concerns, the images available do not include any military installations in India.

Explanation

Acid rain occurs when certain pollutants in the atmosphere react with water vapor to form acids, which then fall to the ground as rain, snow, or fog. The pollutants responsible for acid rain are primarily oxides of nitrogen and oxides of sulfur.

Option 1 is incorrect: Hydrogen itself does not form acidic oxides under typical environmental conditions. The concept of oxides of hydrogen is not commonly associated with acid rain.

Option 2 is correct: Nitrogen oxides, such as nitrogen dioxide, combine with water vapor in the atmosphere to form nitric acid, which contributes to acid rain.

Option 3 is correct: Sulfur oxides, such as sulfur dioxide, react with water vapor to form sulfuric acid, which is another major contributor to acid rain.

Explanation

When carbon monoxide (CO) is inhaled, it binds to hemoglobin in red blood cells with a much stronger affinity than oxygen. Hemoglobin normally binds to oxygen to transport it throughout the body, but CO binds more tightly, forming carboxyhemoglobin. This reduces the ability of hemoglobin to carry oxygen effectively, leading to a decrease in oxygen supply to vital organs and tissues. Carbon monoxide (CO) has approximately 200-250 times more affinity for hemoglobin than oxygen, which means it competes with oxygen for binding sites on hemoglobin.

Explanation

Maize is widely cultivated for the production of ethanol, which is used as a biofuel. Ethanol is derived from the fermentation of sugars and starches found in maize kernels. The United States and Brazil are among the largest producers of maize-based ethanol, which serves as a renewable energy source and an alternative to fossil fuels. Options (a), (c), and (d) are incorrect:

Jatropha is primarily cultivated for its seeds, which contain oil that can be converted into biodiesel. It is not used for ethanol production because it does not contain significant amounts of starch or sugars that can be fermented into ethanol. Pongamia (also known as Millettia pinnata) is an oilseed crop. Its seeds contain oil that are used popularly for biodiesel for biodiesel production, not ethanol. Sunflower is primarily grown for edible oil production, sunflower does not have the starch or sugar content necessary for ethanol production.

Explanation

Insectivorous plants like Venus flytraps and pitcher plants grow in nitrogen-poor, acidic, or waterlogged soils. They capture and digest insects to obtain essential nutrients such as nitrogen and phosphorus which are scarce in their environment. This adaptation allows them to thrive in nutrient-deficient habitats where other plants struggle. Though they perform photosynthesis but their carnivorous behavior supplements their nutritional needs which enables them to survive in challenging conditions.

Explanation

Mon 863 maize was genetically modified to produce a protein called Cry3Bb1 derived from the soil bacterium Bacillus thuringiensis (Bt). This protein is toxic to the corn rootworm which is a major pest that damages maize crops. By incorporating this trait, Mon 863 reduces the need for chemical pesticides and improves crop yields.

Explanation

Option (a) is correct: Statement 1 is correct:

Coffee plants (Coffea arabica and Coffea robusta) thrive in hot tropical climates with temperatures between 15°C and 28°C, high humidity, and well-distributed rainfall. They are typically grown in regions near the equator such as Brazil, Colombia, and Ethiopia. Tea plants (Camellia sinensis) can be grown in both tropical and subtropical regions. They prefer cooler climates with temperatures between 13°C and 30°C and require well-distributed rainfall. Tea is cultivated in countries like India (Assam, Darjeeling), China, and Kenya.

Statement 2 is incorrect: Coffee plants are more commonly propagated from seeds. Seeds are sown to produce seedlings, which are then transplanted to the field. This method ensures genetic diversity among coffee plants. Tea is propagated by both seeds and stem cuttings. The vegetative propagation (stem cuttings) is more common in commercial cultivation because it ensures uniformity in plant characteristics and quality. Differences between Coffee and Tea Cultivation:

Factor Coffee Tea Climate Warm, humid tropical climate Cool, humid subtropical/tropical climate Temperature 15°C - 30°C 13°C - 30°C Rainfall 1,500 - 2,500 mm (moderate) 1,500 - 3,000 mm (higher) Altitude 600 - 2,000 meters 150 - 2,000 meters Soil Type Well-drained, slightly acidic (pH 6-6.5), loamy or volcanic soil Deep, fertile, well-drained acidic soil (pH 4.5-5.5) Shade vs. Sunlight Prefers shade for humidity Prefers open sunlight Temperature Sensitivity Sensitive to frost and extreme heat More adaptable but sensitive to extreme cold Major Growing Regions (India) Karnataka, Kerala, Tamil Nadu (Western Ghats) Assam, West Bengal (Darjeeling), Tamil Nadu (Nilgiris), Kerala Harvesting Beans are handpicked, fermented, dried, and roasted Leaves are plucked, withered, oxidized (for black tea), and dried Processing Roasting required before consumption Processed into different types (green, black, white, oolong)

Explanation

Option 1 is correct: Crop rotation helps maintain soil fertility by alternating crops that deplete nutrients with those that replenish them. It also reduces soil erosion by providing continuous ground cover. Thus, it plays a crucial role in soil conservation and sustainable agriculture.

Option 2 is correct: Sand fences are barriers placed to prevent the movement of sand and reduce soil erosion in arid and semi-arid regions, such as Rajasthan.

Option 3 is correct: Terracing involves cutting steps into slopes to reduce water runoff and prevent soil erosion, particularly in hilly areas. It is widely practiced in regions like the Himalayas.

Option 4 is correct: Wind breaks are rows of trees or shrubs planted to block the wind, reducing wind erosion and protecting the topsoil in open areas.

Explanation

Statement 1 is correct: Pongamia pinnata, also known as the Indian beech tree, grows naturally in arid and semi-arid regions of India. It is highly drought-tolerant, making it a suitable biodiesel crop for areas with limited water availability.

Statement 2 is correct: The seeds of Pongamia pinnata are rich in lipid content(oleic acid) which is a key component in the production of biodiesel. The high oil yield from the seeds makes Pongamia a viable and sustainable biodiesel source. Recently, it has been used for ethanol production.