General Science Questions (MCQs) for Competitive Examinations

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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.

Notes:
Lysosomes are called the suicide bags of the cells they contain digestive enzymes, and break down food, cellular debris and foreign invaders like bacteria. When the cell is injured beyond repair, or becomes old, the lysosome digests the cell. So, it is called “suicide bag of the cell.”

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Greenhouse gases that occur both naturally and from human activities include water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and ozone (O3). These gases contribute to atmospheric warming when they absorb infrared radiation emitted by the solar-warmed Earth and transfer their extra energy to the surrounding atmospheric gases.

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Coconut water, the clear liquid inside young green coconuts (fruits of the coconut palm), is liquid endosperm. In early development, it serves as a sus pension for the endosperm of the coconut during their nuclear phase of development. It contains sugars, vitamins, minerals, proteins, free amino acids and growth promoting factors.

Notes:
The swim bladder is an internal gas-filled organ that contributes to the ability of a fish to control its buoyancy, and thus to stay at the current water depth without having to waste energy in swimming. The cartilaginous fish (e.g. sharks and rays) split from the other fishes about 420 million years ago and lack both lungs and swim bladders, suggesting that these structures evolved after that split.

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Antigens are defined as substances recognized by the body as foreign, causing the body to produce an antibody to react specifically with it. Antibodies are proteins produced by lymphocytes as a result of stimulation by an antigen which can then interact specifically with that particular antigen.

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The urinary bladder is a hollow muscular organ that collects and stores urine from the kidneys before disposal by urination. In humans, the bladder is a hollow muscular organ situated at the base of the pelvis. Urine enters the bladder via the ureters and exits via the urethra.

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Bacteria are the most abundant organisms which play important role in the decomposition of organic matter. Majority of bacteria involved in decomposition of organic matter are heterotrophs and autotrophs are least in proportion which are not directly involved in organic matter decomposition.

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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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Sulphur dioxide (SO2) is considered as the most serious single air pollutant causing health hazard, obstructing breathing. It always leads to airways inflammation, eye irritation, psychic alterations, pulmonary oedema, heart failure and circulatory collapse. It is also responsible for acid rain.