General Science Questions (MCQs) for Competitive Examinations

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Cell theory was first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann. They stated that all organisms are composed of one or more cells, that cells are the fundamental unit of structure and function in all living organisms, and that all cells come from pre-existing cells.

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Buccal cavity (oral cavity) refers to the mouth cavity: the beginning of the alimentary canal, which leads to the pharynx and (in vertebrates) to the oesophagus. It is part of the digestive system. In mammals it contains the tongue and teeth, which assist in the mechanical breakdown of food, and the openings of the salivary glands.

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Deciduous means “falling off at maturity” or “tending to fall off”. Deciduous trees or shrubs lose their leaves seasonally. The converse of deciduous is evergreen.

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Aflatoxin are naturally occurring mycotoxins that are produced by Aspergillus flavus and Aspergillus parasiticus, species of fungi. They have been associated with various diseases, such as aflatoxicosis, in livestock, domestic animals and humans throughout the world.

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Bioremediation is a waste management technique that involves the use of organisms to remove or neutralize pollutants from a contaminated site. It uses naturally occurring organisms to break down hazardous substances into less toxic or non-toxic substances. There are two classes of bioremediation used : In situ and Ex situ.

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Chloramines are a group of chemical compounds that contain chlorine and ammonia. It is used as a disinfectant for water. The particular type of chloramine used in drinking water disinfection is called monochloramine. However, it is used as a secondary disinfectant that are added to water that has already been disinfected with a primary disinfectant, often chlorine using bleaching powder.

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The bark of cinchona tree yields quinine, a white crystalline alkaloid having antipyretic (fever-reducing), anti-malarial, analgesic (painkilling), and anti-inflammatory properties. Quinine was the first effective Western treatment for malaria caused by Plasmodium falciparum.

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Scurvy also once called ‘Sailor’s disease’ is a condition where an individual has a vitamin C (ascorbic acid) deficiency. Scurvy often presents itself initially as symptoms of malaise and lethargy, followed by formation of spots on the skin, spongy gums, and bleeding from the mucous membranes. Spots are most abundant on the thighs and legs, and a person with the ailment looks pale, feels depressed, and is partially immobilized. As scurvy advances, there can be open, suppurating wounds, loss of teeth, jaundice, fever, neuropathy and death.

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The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some subsurface layers. It is found in salt water ecosystem. The benthic region of the ocean begins at the shore line and extends downward along the surface of the continental shelf out to sea.

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In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.