Biology MCQs

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The Actinobacteria are a phylum of Gram-positive bacteria. They can be terrestrial or aquatic. It is known to produce a wide variety of industrially and medically relevant compounds like Antibiotics, etc.

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pH stands for potential hydrogen. It is used to describe the chemical acidity level vs. alkalinity level of a substance. The pH of Healthy human saliva is slightly alkaline and in the range of 6.2 to 7.6.

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Helophyte are those plants which are typical of marshy or lake-edge environments, in which the perennating organ lies in soil or mud below the water level, but the aerial shoots protrude above the water for air.

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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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The phenomenon that causes animals to sweat to reduce temperature and change electrolyte concentration is homeostasis. When core body temperature increases, sweat glands respond by cooling the skin. Blood vessels also dilate, which allows the body to release more heat. Sweating is a rare ability in the animal kingdom. For example, rats don’t sweat when their core body temperature rises to 41°C. However, they do sweat in response to pilocarpine and other cholinergic agonists.

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Down syndrome mainly affects hearing, vision, the circulatory system and the bone systems. 

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Taenia is a taxonomic rank of tapeworm (helminth) that includes some main parasites of livestock. There are more than 100 species of Taenia. Taenia is responsible for taeniasis and cysticercosis in humans. They are morphologically characterized by a ribbon like body composed of a series of segments called proglottids.

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In Mitochondria, pyruvic acid is broken down into carbon dioxide, water and energy.

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Cell division is the process by which a Unicellular Organism reproduce and divides into two or more daughter cells. Cell division usually occurs as part of a larger cell cycle.

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Biogas or Gobar gas is produced by the breakdown of organic matter in the absence of oxygen. It can be produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste. It is a renewable energy source. It comprises primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes. It is produced by anaerobic digestion.