General Science Questions (MCQs) for Competitive Examinations

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In 1897, J.J. Thomson discovered the electron by experimenting with a Crookes, or cathode ray, tube. He demonstrated that cathode rays were negatively charged.

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Steel is an alloy made by combining iron and other elements, the most common of these being carbon. When carbon is used, its content in the steel is between 0.2% and 2. 1% by weight, depending on the grade. Other alloying elements sometimes used are manganese, chromium, vanadium and tungsten. Carbon and other elements act as a hardening agent, preventing dislocations in the iron atom crystal lattice from sliding past one another.

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Keratin is a family of fibrous structural proteins involved in making up the outer layer of human skin. It is also the key structural component of hair and nails. Cells in the epidermis contain a structural matrix of keratin, which makes this outermost layer of the skin almost waterproof, and along with collagen and elastin, gives skin its strength. It also makes up fish scales and crustacean shells, bird feathers and beaks, animal horns and hooves.

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Glycolysis, part of cellular respiration, is a series of reactions that constitute the first phase of most carbohydrate catabolism, catabolism meaning the breaking down of larger molecules into smaller ones. Glycolysis breaks down glucose and forms pyruvate with the production of two molecules of ATP. The entire process from conversion of glucose to pyruvate is anaerobic that is it does not take place in presence of oxygen.

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Pulses are part of the legume family, but the term “pulse” refers only to the dried seed. Dried peas, edible beans, lentils and chickpeas are the most common varieties of pulses. The term “legume” refers to the plants whose fruit is enclosed in a pod. Other well-known legumes include alfalfa, clover, fresh peas, lupins, mesquite, soy and peanuts.

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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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Histology is the study of the micro anatomy of cells, tissues, and organs as seen through a microscope. It examines the correlation between structure and fun-ction.Histology is the micro-scopic counterpart to gross anatomy which looks at larger structures visible without a microscope.

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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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Vitamin C is quite unstable when cooked or stored improperly. It is very liable and easily destroyed during cooking as well as storage. It is a water-soluble and temperature-sensitive vitamin, so is easily degraded during cooking, and elevated temperatures and long cooking times have been found to cause particularly severe losses of vitamin C.

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While fertilization is necessary for organisms that reproduce sexually, individuals that reproduce asexually?do so without the need for fertilization. These organisms produce genetically identical copies of themselves through?binary fission, budding, fragmentation, parthenogenesis, or other forms of asexual reproduction.