General Science Questions (MCQs) for Competitive Examinations

Notes:
The melting point of a pure substance is always higher than the melting point of that substance when a small amount of an impurity is present. Melting point decreases with increase of impurity in water. Increase in impurity increases the electrostatic attraction between ions and thus more energy is needed to break the bonds. The surface tension of water increases when highly soluble impurities are added to it.

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All metal carbonates and hydrogen carbonates react with acids to give a corresponding salt, carbon dioxide and water. Limestone, chalk and marble are different forms of calcium carbonate.

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Carbon monoxide poisoning can be cured by exposing the affected person to fresh oxygen. It is because CO posoning leads to oxygen starvation of body cells. This therapy involves breathing pure oxygen in a chamber in which the air pressure is about two to three times higher than normal. This speeds the replacement of carbon monoxide with oxygen in your blood. Hyperbaric oxygen therapy may be used in cases of severe carbon monoxide poisoning.

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Cnidarian, also called coelenterate, any member of the phylum Cnidaria (Coelenterata), a group made up of more than 9,000 living species. ? Mostly marine animals, the cnidarians include the corals, hydras, jellyfish, Portuguese men-of-war, sea anemones, sea pens, sea whips, and sea fans.

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Veins carry the deoxygenated blood from different parts of the body to the heart. There are two main veins that carry out this job. The superior vena cava carries deoxygenated blood from head, neck, thorax and hands to the right atrium of our heart. The inferior vena cava carries deoxygenated blood from legs, pelvic region and abdominal organs to the right atrium of our heart. Among the veins, only pulmonary vein carries oxygenated blood.

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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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Penicillin the so called ‘Wonder drug’ discovered by Alexander Fleming in 1927 is produced from the genus of fungi “Penicillia”. All penicillin are â-lactam antibiotics and are used in the treatment of bacterial infections caused by susceptible, usually Grampositive organisms.

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Photosynthesis is the process by which light energy is converted into chemical energy by organisms. Carbon dioxide and water are the raw materials of this process. The light energy comes from the Sun and its end products are oxygen and glucose.

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Protein electrophoresis and Western blotting are both methods used to identify specific proteins in a sample or solution. Western blotting, also known as immunoblotting or protein blotting, is a core technique in cell and molecular biology. It is used to detect the presence of a specific protein in a complex mixture extracted from cells.

Notes:
Protein digestion begins in the stomach with the action of pepsin. Pepsin is the active protein-digesting enzyme of the stomach. When pepsin acts on the protein molecule, it breaks the bonds that hold the protein molecule together, called peptide bonds. Once broken, peptide bonds yield chains of amino acids linked together called polypeptides that are further digested in the small intestine with the help of trypsin, chymotrypsin, and carboxypeptidase.