UPSC 2013 Prelims Questions with Answers

Explanation

After harvest, fruits and vegetables remain metabolically active, with respiration being a key manifestation of this activity. Respiration involves the breakdown of stored nutrients to release energy for cellular processes. This process can be effectively slowed by lowering the temperature, which decreases the metabolic rate. Since harvested fruits and vegetables are no longer connected to the plant’s roots, they cannot acquire additional nutrients. As a result, they rely entirely on their stored nutrients for energy. Once these reserves are depleted, the produce begins to degrade. Therefore, controlling the rate of respiration through proper storage conditions, such as refrigeration, is crucial to preserving fruits and vegetables for longer periods and maintaining their quality.

Explanation

Ball bearings are used to reduce friction between the surfaces. A ball bearing is a specific kind of rolling-element bearing that uses balls to keep the bearing races apart. A ball bearing’s main functions are to support radial and axial loads and lessen rotational friction. In order to reduce friction between surfaces and also because the effective area of contact between the wheel and axle is reduced, ball bearings are used in bicycles, vehicle axles, etc.

Explanation

A rainbow is formed when sunlight interacts with raindrops in the atmosphere, and this process involves three key physical phenomena: dispersion, refraction, and internal reflection. Dispersion occurs as sunlight, which consists of multiple colors, is separated into its constituent wavelengths when it passes through a raindrop, with each color bending by a different angle. Refraction takes place at the interface of air and water when sunlight enters the raindrop, causing the light to bend due to a change in its speed. This bending happens twice--first as the light enters the drop and again as it exits. Internal reflection occurs when the light, after being refracted, reflects off the inner surface of the raindrop. The combined effect of these phenomena results in the formation of a colorful arc in the sky, known as a rainbow.

Explanation

Transplanted seedlings often experience root injury during transplantation, which can lead to difficulties in establishment and growth. The majority of the water that is finally delivered to the plant’s top growth is absorbed by tiny roots that are farther from the plant and are covered by even smaller hairs. These delicate roots are typically killed after a transplant either by being chopped to reduce the size of the root ball or by drying out. It’s referred to as transplant shock. Transplant shock refers to a number of stresses that occur in recently transplanted trees and shrubs. It involves failure of the plant to root well, consequently the plant establishes poorly in the landscape. New transplants frequently experience stress due to a shortage of water because their root systems are not yet well established. Water stressed plants may be more vulnerable to harm from other factors, such as the environment, insects, or disease.

Explanation

Fundamental forces of nature can be categorised in four categories like Gravitational force, Weak Nuclear force, Electromagnetic force and Strong Nuclear force. Notably, latter three forces are all part of the Standard Model of physics Gravity and the electromagnetic force both have an unlimited range. However, despite its infinite reach, gravity is the weakest of the four fundamental forces. In contrast, the strong nuclear force is the strongest but operates only over a very short range. Strong Nuclear Force > Electromagnetic Force > Weak Nuclear Force > Gravitational Force. Options (b), (c) and (d) are correct:

Electromagnetic Force is weaker than the strong nuclear force. It acts between electrically charged particles. It also has infinite range and is attractive or repulsive. The Weak Nuclear Force is very weak and causes radioactive decay. It governs particle decay. It has a short-range. Strong Nuclear Force as the name suggests is very strong but has a short-range. It holds protons and neutrons inside the nucleus of the atom.

Explanation

The Ilbert Bill Controversy (1883) arose from Lord Ripon’s attempt to reform India’s legal system. Under the existing laws, a European could be tried only by a European judge or magistrate, which was seen as discriminatory against Indian judges. To end this injustice, C.P. Ilbert proposed a bill in 1883 that would allow Indian judges to try Europeans. The proposal faced strong opposition from the European community in India. The Ilbert Bill controversy made educated Indians aware of the need of an all Indian organisation, resulting in the formation of Indian National Congress in 1885.

Explanation

Contour bunding is a soil conservation technique primarily employed in hilly or sloping terrains to combat soil erosion and enhance water retention. This method involves constructing embankments, or "bunds," along the natural contour lines of the landscape. These bunds act as barriers that slow down water runoff, promote water infiltration and reduce the loss of topsoil. Options (a), (b) and (c) are incorrect:

Contour bunding is not suitable for desert margins or areas prone to strong wind action. Wind erosion is better controlled by techniques like windbreaks or shelterbelts, not contour bunding. In low-lying flat plains prone to flooding contour bunding is less effective. Flood management and soil conservation in these areas often involves levees, dykes, or drainage systems rather than contour bunds. Contour bunding is not specifically designed for scrublands prone to weed growth. Weed control requires different management practices, such as mechanical or chemical weeding methods.

Explanation

The nitrogen cycle is a crucial process that maintains the soil fertility necessary for plant growth.

Statement 1 is correct: Animals excrete urea through urine containing nitrogen. When this urea is deposited onto the soil, soil microorganisms break it down through a process called mineralization, converting it into ammonium (NH₄ +), which can readily absorbed by plants.

Statement 2 is incorrect: While the burning of coal releases nitrogen oxides (NOx) into the atmosphere, it does not directly add nitrogen to the soil. Instead, the pollutants can contribute to air pollution and acid rain, which may eventually affect soil quality but not in a beneficial way for nitrogen enrichment of soil.

Statement 3 is correct: The death and decomposition of vegetation naturally adds nitrogen to the soil. When plants die, their organic matter decomposes due to microbial activity. During de-composition, nitrogen is released in the form of ammonium and nitrates, which then enrich the soil. This recycling of nutrients is a natural and critical component of the nitrogen cycle.

Explanation

Option 1 is correct: The Gharial is critically endangered. Once found across the Indian subcontinent, its population has drastically declined due to habitat loss, reduction in prey species, entanglement in fishing nets, and water pollution. It is now confined to a few river systems, especially in the Chambal River. The Gharial is listed as critically endangered by the IUCN Red List.

Option 2 is correct: The Leatherback turtle is the largest species of sea turtle and is listed as vulnerable by the IUCN. The species faces numerous threats, including accidental capture in fishing nets, habitat destruction (especially nesting sites), and illegal hunting. It is found along India’s coasts, particularly in the Andaman and Nicobar Islands and parts of the Tamil Nadu coast. However many subpopulations (such as in the Pacific and Southwest Atlantic) are Critically Endangered.

Option 3 is correct: The Swamp deer (also called the Barasingha) is endangered. It is found in wetland areas in parts of In-dia, such as Uttarakhand and Madhya Pradesh. Habitat destruction, hunting, and the drainage of wetlands have contributed to its population decline. Note: According to UPSC Answer Key Option C is correct

Explanation

Option 1 is correct: Star Tortoise (Geochelone ele-gans) is naturally found in India. It is a species of tortoise that inhabits the dry forests and scrublands of India, particularly in Rajasthan, Gujarat, Madhya Pradesh, and parts of Tamil Nadu. It is easily recognizable due to the star-like patterns on its shell. The species is endangered due to habitat loss and illegal trade. There is a huge international demand for these animals as exotic pets which threatens their survival.

Option 2 is correct: Monitor lizards are found in India and are widespread across the country. Several species, including the Indian monitor lizard (Varanus bengalensis), can be found in forests, grasslands, and even near human settlements. These lizards are known for their size, strength, and scavenging habits.

Option 3 is correct: Pygmy Hog (Porcula salvania) is naturally found in India, specifically in the grasslands of Assam. It is a critically endangered species and is the smallest wild pig in the world. The Pygmy hog’s population has been reduced due to habitat destruction, especially the loss of grasslands in the region.

Statement 4 is incorrect: The Spider monkey is not naturally found in India. It is native to Central and South America, specifically the tropical forests of the Amazon Basin.