General Science Questions (MCQs) for Competitive Examinations

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Electron was discovered by an Irish scientist J J Thomson and electron is the first subatomic particle to be discovered. J J Thomson is notable for proposing the water melon model which is also called as plum pudding model.

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Fermentation is an anaerobic chemical process that breaks down glucose molecules. In baking, yeast consumes sugar and converts it into carbon dioxide and alcohol, making the dough rise. This gas gets trapped in the strands of gluten, resulting in air pockets that cause the dough to rise and form the characteristic spongy texture of bread and cakes. Further, the creation of lactic and acetic acids during fermentation augments this dough handling process, improves flavor, enhances the texture, and extends the shelf-life of the baked products.

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Edible seaweed products have been consumed in many Asian countries. Edible seaweeds accumulate iodine from seawater and are therefore a good dietary source of iodine. Adequate consumption of seaweed can eliminate iodine deficiency disorders, but excessive iodine intake is not good for health. The recommended dietary reference intake of 0.15 mg/d and 0.14 mg/d for iodine has been established in the United States and Taiwan, respectively. Seaweed is an excellent source of iodine. However, the amount it contains depends on the species. Kombu kelp offers the highest amount of iodine, with some varieties containing nearly 2,000% of the daily value in one gram. Seaweed is a source of iodine, necessary for thyroid function and to prevent goitre. However, an excess of iodine is suspected in the heightened cancer risk in Japanese who consume a lot of the plant, and even bigger risks in post-menopausal women.

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Chickenpox, also known as varicella, is a highly contagious infection caused by the varicella zoster virus. The disease results in a characteristic skin rash that forms small, itchy blisters, which eventually scab over. It is an airborne disease which spreads easily through the coughs and sneezes of an infected person.

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Pituitary gland, called Master Gland, is the smallest endocrine gland. It controls the general growth of the body coordinating the functioning of other endo crime glands and stimulates the primary sex hormones, i.e. ovaries and testes.

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Haemoglobin is called as tetrameric hemoprotein, while myoglobin is called monomeric protein. Haemoglobin is found systematically all over the body, while myo-globin is found in muscles tissues only. The body requires iron for the synthesis of its oxygen transport proteins, in particular hemo-globin and myoglobin.

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Nitrogen-fixing bacteria are microorganisms capable of transforming atmospheric nitrogen into fixed nitrogen. Rhizobium is one such bacteria that is associated with leguminous plants (e.g., various members of the pea family). It invades the root hairs of host plants and convert free nitrogen to ammonia, which the host plant utilizes for its development.

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Fluorine is the element that is associated with teeth disorder because the presence of sodium fluoride in drinking water at the level of 2ppm may cause mottled enamel in teeth, skeletal fluorosis, and may be associated with cancer and other diseases. However, topically applied fluoride (toothpaste, dental rinses) has been shown to help reduce dental caries.

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Growth hormone or somatotropin, also known as human growth hormone in its human form, is a peptide hormone that stimulates growth, cell reproduction and cell regeneration in humans and other animals. It is thus important in human development.

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Biochemical Oxygen Demand or Biological Oxygen Demand, is a measurement of the amount of dissolved oxygen (DO) that is used by aerobic microorganisms when decomposing organic matter in water. It indicates the amount of putrescible organic matter present in water. Therefore, a low BOD is an indicator of good quality water, while a high BOD indicates polluted water.