General Science Questions (MCQs) for Competitive Examinations

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Green is the least effective color of light in driving photosynthesis, the process of converting light energy into chemical energy. Photosynthesis occurs in plants and algae using chlorophyll, and because chlorophyll reflects rather than absorbs green light, green light cannot be used in the photosynthetic process.

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White blood cells (WBCs) are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. They are also called leukocytes. WBCs are found throughout the body, including the blood and lymphatic system.

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Pasteurisation is a process of heating milk for 30 minutes at 62° C and cooling rapidly to kill harmful bacteria and prevent their further proliferaction. Because of the nature of the heat treatment it sometimes referred to as the ‘High Temperature Short Time’ (HTST) process. Once the milk has been heated, it is then cooled very quickly to less than 3°C.

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An insect is an organism having three pairs of jointed legs. Insects are small, land-dwelling arthropods. It has three distinct body sections : the head, thorax and abdomen. It has one pair of antennae (comprising the scapele, pedicel and flagellum), compound eyes and often one or two pairs of wings.

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Carbohydrates are the main and quick energy source for human beings. Simple carbohydrates (like sugar-sweetened beverages) are digested quickly and send immediate bursts of glucose (energy) into the blood stream. Complex carbohydrates are digested more slowly and supply a lower steadier release of glucose into the blood stream.

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Insulin is a hormone secreted by the pancreas that is important for metabolism and utilization of energy from the ingested nutrients – especially glucose. It keeps our blood sugar level from getting too high (hyperglycemia) or too low (hypoglycemia). The pancreas is a glandular organ in the digestive system and endocrine system of vertebrates.

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Pleiotropy describes the genetic effect of a single gene on multiple phenotypic traits. The underlying mechanism is that the gene codes for a product that is, for example, used by various cells, or has a signaling function on various targets. A classic example of pleiotropy is phenylketonuria, a human disease that affects multiple systems but is caused by one gene defect.

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Fructose, or fruit sugar, is a simple ketonic monosaccharide found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is a 6-carbon polyhydroxyketone with chemical formula of C6H12O6.

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The deficiency of magnesium leads to yellowish green blotch near the base of the leaf between the midrib and the outer edge (chlorosis). The yellow area enlarges until the only green remaining is at the tip and base of the leaf as an inverted V-shaped area on the midrib.

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Deciduous means “falling off at maturity” or “tending to fall off”. Deciduous trees or shrubs lose their leaves seasonally. The converse of deciduous is evergreen.