Miscellaneous: UPSC Previous Year Questions (Science and Technology)

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.