General Science Questions (MCQs) for Competitive Examinations

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Chemical weapons are called “poorman’s bomb”. These cause catastrophic damage, and are easy to produce. Sarin is a colorless and odourless agent, and is extremely potent. It was used in Damascus in 2013. Mustard Gas is possibly the most commonly used chemical agent and gets its name from the distinctive odour of rotten mustard. It is less potent and usually only 5 to 10 percent people exposed to it usually die. It was widely used during Second World War. VX is a nerve agent which is odourless and appears as brownish oily substance.

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Sublimation describes a phase transition where a substance changes from a solid directly to a gas, bypassing the liquid state. This physical transformation is distinct from chemical changes like oxidation or reduction. Sublimation happens under certain combinations of pressure and temperature. Examples include dry ice (solid CO2), which sublimates at room temperature, and solid water, or ice, which sublimates under low pressure conditions.

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Typhoid is a common worldwide bacterial disease transmitted by the ingestion of food or water contaminated with the feces of an infected person, which contain the bacterium Salmonella enterica subsp. enterica, serovar Typhi.

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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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Heart rate is controlled by the two branches of the autonomic (involuntary) nervous system. The sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The sympathetic nervous system (SNS) releases the hormones (catecholamine – epinephrine) to accelerate the heart rate. The parasympathetic nervous system (PNS) releases the hormone acetylcholine to slow the heart rate.

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The phosphate groups on DNA are ionic and charged. Each phosphate group on the DNA backbone has one unit of negative charge (-1). Charged molecules attract water and are hydrophilic. DNA has two hydrophilic polar external backbones made of sugars and phosphate groups joined by ester bonds. Therefore, DNA as nucleic acid is characterized by presence of phosphodiester bond.

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Plants which either obtain readymade organic food prepared by other plants or absorb water and minerals from other plants to prepare their own organic food are called parasitic plants. Cuscuta (Doddar) is a total stem parasite.

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The dodo (Raphus cucullatus) is an extinct flightless bird that was endemic to the island of Mauritius, east of Madagascar in the Indian Ocean. Subfossil remains show the dodo was about 1 metre (3 ft 3 in) tall and may have weighed 10.6–17.5 kg (23– 39 lb) in the wild. The closest living relative of the dodo is the Nicobar pigeon.

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“Animalcule” is a old term for a microorganism first used by Anton Van Leeuwenhoek means “small animal”. A paramecium is shaped somewhat like a slipper (a soft shoe), so it is called the slipper animalcule. Other better-known animalcules include: Amoeba, called Proteus animalcule etc.

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Red rot disease is caused by the fungus Glomerella tucumanensis. An older name,Colletotrichum falcatum, is still preferred by some pathologists. Red rot occurs in various parts of the sugar cane plant but it is usually considered a stalk and a seed-piece disease. Its symptoms are highly variable depending upon the susceptibility of the sugarcane variety and the environment.