Biology MCQs

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Nitrates in drinking water can cause “blue baby syndrome”, which is a condition where infants have a reduced ability to carry oxygen in the blood (methemoglobinemia). The nitrates interfere with the oxygen carrying capacity of hemoglobin. This causes the skin to appear blue or purple. Nitrates in drinking water, often from agricultural runoff, are the cause of “blue baby syndrome”.

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Rhizobium Found in roots of legumes, like Peas, grams, Pulses etc, where it fixes atmospheric nitrogen as ammonia, which is then converted into useful amino acid.

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The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. It is considered to have the Least generative power.

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Blood plasma is the liquid component of whole blood, and makes up approximately 55% of the total blood volume. It is composed primarily of water with small amounts of minerals, salts, ions, nutrients, and proteins in solution. In whole blood, red blood cells, leukocytes, and platelets are suspended within the plasma.

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The cultivation of Jatropha curcas on wastelands has a potential to generate biofuel in large quantities. It is a species of flowering plant in the spurge family called Euphorbiaceae, that is native to the American tropics, most likely in Mexico and Central America.

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In population ecology and demography, the net reproduction rate is defined as the average number of offspring that would be born to a female if she passed through her fertility age. Or simply The rate at which women are replaced by daughters who will have children.

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Bryophytes are an informal group consisting of three divisions of non-vascular land plants: the liverworts, hornworts and mosses. They play a vital role in regulating ecosystems because they provide an important buffer system for other plants.

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Dr. Robert Koch was a German (Prussian) physician. In 1877 he isolated Bacillus anthracis (causative agent of Anthrax) . He also isolated Tuberculosis bacillus (Causative agent of TB) and Vibrio cholera (causative agent of Cholera). He is also known to develop Koch’s postulates, the four criteria designed to establish a causal relationship between a causative microbe and a disease. He was awarded the Nobel Prize in Physiology or Medicine for his tuberculosis findings in 1905.

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For reasons of safe transportation of fruits, mangoes, bananas etc are picked before they ripen fully. Slightly green harvested mangoes are subjected to small containers of calcium carbide (CaC2) with a plastic covering. CaC2 reacts with the moisture in the air to release acetylene (or ethyne) gas as follows:
CaC2 + 2 H2O – C2H2 + Ca(OH)2
This option may give you slightest confusion if you don’t know the difference between Ethylene and Ethyne (Acetylene). Both are chemical substances produced by fruits to accelerate the normal process of fruit maturation — is a ripening hormone. Ethylene is C2H4 and has a carbon-carbon double bond. Acetylene is C2H2 and has a carbon-carbon triple bind. Acetylene contains more energy and burns hotter than ethylene. Ethylene is a gaseous compound , Acetylene is the chemical compound , which is the simplest alkyne and is also a hydrocarbon while Ethylene is the simplest alkene and classified as an unsaturated hydrocarbon. I hope you will never forget it now.

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Sucralose is an artificial sweetener. The majority of ingested sucralose is not broken down by the body and therefore it is non-caloric. Sucralose is approximately 600 times as sweet as sucrose (table sugar), twice as sweet as saccharin, and 3 times as sweet as aspartame. It is stable under heat and over a broad range of pH conditions. Therefore, it can be used in baking or in products that require a longer shelf life. The commercial success of sucralose-based products stems from its favorable comparison to other low-calorie sweeteners in terms of taste, stability, and safety. It is used because it is a no-calorie sweetener, and does not promote dental cavities, is safe for consumption by diabetics, and does not affect insulin levels.