General Science Questions (MCQs) for Competitive Examinations

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Alfred Bernhard Nobel was a Swedish chemist, engineer, inventor, businessman, and philanthropist. Atomic number 102 was named after him.

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Radon, a radioactive noble gas with atomic number 86, is used in radiotherapy. Created by disintegration of radium, its one of the heaviest gases and a health hazard. Radon gas, chemically inert yet radioactive, can accumulate in buildings and drinking water causing lung cancer. Furthermore, radon is noted for brilliant phosphorescence when cooled below its freezing point. Its most stable isotope, 222Rn, has a half-life of 3.8 days. Groundwater often has a higher 222Rn concentration than surface water due to less exposure to atmosphere.

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Chickenpox, also known as varicella, is a highly contagious infection caused by the varicella zoster virus. The disease results in a characteristic skin rash that forms small, itchy blisters, which eventually scab over. It is an airborne disease which spreads easily through the coughs and sneezes of an infected person.

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Keratin is a family of fibrous structural proteins that is the key structural component of hair and nails. It is also the key structural material making up the outer layer of human skin. Besides, it provides the necessary strength and toughness for masticatory organs, such as the tongue.

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Milk is a poor source of ascorbic acid (Vitamin C). It contains about 1 mg ascorbate per 100 g. Even the little Vitamin C is usually destroyed when the milk is heat treated. Milk as a complete food contains most of the esential nutrients except are vitamin C and iron.

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Plant wilting occurs after excessive loss of water by transpiration and lesser absorption. i.e. rate of transpiration exceeds rate of water absorption. On a hot day, plants transpire heavily and cannot absorb water speedily to keep pace with transpiration loss, even when there is enough water.

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Tuberculosis caused by Mycobacterium tuberculie which primarily affects lungs although can affect other body too while early 19th century was called ‘white plague’ because of the large number of the people dying of its infection.

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Anaerobic reactions involve break down of glucose into pyruvic acid, which then reacts to produce lactic acid. As muscle metabolism shifts from aerobic to anaerobic ATP production, lactic acid begins to accumulate in muscles and to appear in the bloodstream. This leads to muscle fatigue with changing pH of muscle cells. C6H12O6 —> 2C3H6O3 + 2ATP

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A fossil is the naturally preserved remains or traces of organisms that lived in the geologic past. There are two main types of fossils; body and trace. Body fossils include the remains of organisms that were once living, and trace fossils are the signs that organisms were present (i.e. footprints, tracks, trails, and burrows).

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Cotton is the most popular of the BT crops. In BT cotton, BT gene was isolated and transferred from a bacterium Bacillus thurigiensis to American cotton. The American cotton was subsequently crossed with Indian cotton to introduce the gene into native varieties. The BT cotton variety contains a foreign gene obtained from Bacillus thuringiensis. This bacterial gene, introduced genetically into the cotton seeds, protects the plants from bollworm (A. lepidoptora), a major pest of cotton.