General Science Questions (MCQs) for Competitive Examinations

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Flowers emit fragrance to attract pollinators which are mainly insects. The fragrance plays a prominent role in the localization and selection of flowers by insects, especially moth-pollinated flowers, which are detected and visited at night. If they have become infested with herbivores like caterpillars, they attract beneficial insects like parasitic wasps with the help of scent signals from their leaves.

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Mitochondria is an organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It is for this reason that mitochondria are often referred to as the powerhouses of the cell mitochondria also play a key role in the ageing process as well as in the onset of degenerative disease.

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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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Tuberculosis caused by Mycobacterium tuberculie which primarily affects lungs although can affect other body too while early 19th century was called ‘white plague’ because of the large number of the people dying of its infection.

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Silk worms are the larva of a moth (Bombyx mori) native to Asia that spins a cocoon of fine, strong, lustrous fiber that is the source of commercial silk. Silkworms feed on the leaves of the mulberries (genus- Morus) and sometimes on the Osage orange (Maclura pomifera).

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Nucleic acids are large biological molecules essential for all known forms of life. They include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). They are merely transmitted from one generation to next.

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Animals that have a cavity between body wall and digestive tract are known as coelomates for e.g.. annelids, molluscs, arthropods, Echinodermata, and chordates etc. In contrast, animals in which the body cavity is absent are known as acoelomates. Platyhelminthes is an example of acoelomates. The presence or absence of body cavity or coelom plays a very important role in the classification of animals.

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Yeast are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. They are estimated to constitute 1% of all described fungal species. Yeasts, such as Candida albicans, are opportunistic pathogens and can cause infections in humans. Commercially they are widely used in production of alcohol and carbon dioxide. Hence, they are known to lay foundation of bakery and brewery industries.

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Lipid oxidation is one of the major reasons that foods deteriorate and is caused by the reaction of fats and oils with molecular oxygen leading to off flavours that are generally called rancidity. Exposure to light, pro-oxidants and elevated temperature accelerate the reaction. Rancidity is associated with characteristic off-flavour and odour of the oil.

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Ethanol fermentation, also called alcoholic fermentation, is a biological process which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by products. It is an anaerobic process since Yeasts perform this conversion in the absence of oxygen.