General Science Questions (MCQs) for Competitive Examinations

Notes:
As per the Mohs scale of mineral hardness, the soft metals are: Lead, gold, silver, tin, zinc, aluminium, thorium, copper, brass and bronze. Diamond is one of the hardest known metals on earth.

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Antiseptics are applied to the living tissues such as wounds, cuts, ulcers and diseased skin surfaces. Examples of antiseptics are furacine, soframicine, etc

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The brain’s limbic system controls emotional expression through the hypothalamus, which has control over the body’s emotional responses systems. The hypothalamus is responsible for regulating hunger, thirst, response to pain, levels of pleasure, sexual satisfaction, anger and aggressive behavior, etc. It also regulates pulse, blood pressure, breathing, and arousal in response to emotional circumstances.

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Jaundice is a yellowish pigmentation of the skin, the conjunctival membranes over the sclerae (whites of the eyes), and other mucous membranes caused by hyperbilirubinemia. Concentration of bilirubin in blood plasma does not normally exceed 1 mg/dL (>17?mol/L). A concentration higher than 1.8 mg/ dL (>30?mol/L) leads to jaundice. Jaundice is often seen in liver disease such as hepatitis or liver cancer.

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Calyptrogen is a layer of rapidly dividing cells at the tip of a plant root, from which the root cap is formed. It occurs in grasses and many other plants. The root cap is formed by several layers of cells that envelop the root tip externally. This covering of cells, of which the outermost ones are dead, envelops and protects the growing tip of root.

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Cyanobacteria, also known as blue green algae, are single-celled and belong to the family of Prokaryotes. That means, they do not have a well defined cell nucleus. The ability of cyanobacteria to perform oxygenic photosynthesis is thought to have converted the early reducing atmosphere into an oxidizing one, which dramatically changed the composition of life forms on Earth by stimulating biodiversity and leading to the near-extinction of oxygen-intolerant organisms.

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The average adult has a blood volume of roughly 4-5 to 5 litres, which is composed of plasma and several kinds of cells. By volume, the red blood cells constitute about 45% of whole blood, the plasma about 54.3%, and white cells about 0.7%.

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Monocost and dicots differ in the location of stomata and shape of guard cells. In monocots stomata are Dumb-bell shaped in dicots they are bean-shaped.

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Swedish naturalist Carlous Linnaeus established the binomial system of naming living organisms, setting a format and a structured process for classifying the interrelationships between plants (among which he included all fungi), and between animals. The binomial system that Linnaeus devised enables an author to refer to a species confident that it will mean the same thing to informed readers anywhere else in the world.

Notes:
Hydra is radially symmetrical, that is, the parts of its body are arranged in a circle around a central median axis passing through the mouth. Hydra reproduces by asexual and sexual methods. Asexual reproduction takes place either by budding or by fission.