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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The chief cells of the stomach secrete enzymes for protein breakdown (inactive pepsinogen and rennin). Hydrochloric acid activates pepsinogen into the enzyme pepsin, which then helps digestion by breaking the bonds linking amino acids, a process known as proteolysis.

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Jhum is a traditional form of shifting cultivation that is common in the North-East of India. Also known as slash and burn agriculture, it is practiced by the tribal groups in Arunachal Pradesh, Meghalaya, Mizoram and Nagaland and the hilly areas of Assam. Jhum involves clearing a piece of land by setting fire or clear felling and using the area for growing crops.

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Pond silk is the common name of Spirogyra (algae) because it is very slimy in shape. It is also known as pond silk, water silk, pond scum or mermaid’s trees because of its bright green silky appearance. Its filaments shine like silk due to the presence of mucilage and spiral shaped chloroplast.

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The Taungya system involves growing agricultural crops between rows of planted trees (sal, teak, etc). Along with jhum cultivation, it is one of the well-known systems of agro forestry programmes in practice in our country.

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Utricularia (also called bladderworts) is a genus of insectivorous plants. They occur in fresh water and wet soil as terrestrial or aquatic species. All Utri cularia are carnivorous and capture small organisms by means of bladder-like traps. Aquatic species feed on protozoa and rotifers swimming in water-saturated soil’ while terrestrial species feed on water fleas (Daphnia), nematodes and even fish fry, mosquito larvae and young tadpoles.

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The Theory of Evolution was developed by Charles Darwin (1809-1882). It states that all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual’s ability to compete, survive, and reproduce. The theory gained general scientific acceptance after Darwin published On the Origin of Species in 1859.

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A carnivore is an organism that mostly eats meat, or the flesh of animals. Carnivores that eat herbivores are called secondary consumers, and large carnivores that eat other carnivores are called tertiary consumers. Animals and people who eat both animals and plants are called omnivores. Sometimes carnivores are also called predators.

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Cabbages have no need to store food as they are seasonal plants and die after about 4 to 6 months. They do however produce food in the leaves of the plants and would utilize short-term storage (in the leaves) for simple metabolic processes.