General Science Questions (MCQs) for Competitive Examinations

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Cause of night blindness is a deficiency of retinol, or vitamin A, found in fish oils, liver, dairy products, vegetable and fruits yellow in colour. Nyctalopia also called “Night Blindness” is a condition making it difficult or impossible to see in relatively dim light. To over come deficiency of vitamin-A, one needs to feed of food products rich in carotene which is used in synthesis of vitamin-A is liver.

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Potable water is water of a quality suitable for drinking, cooking and personal bathing. It is water that is safe to drink or to use for food preparation. In developed countries, tap water is usually potable.

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Herbivorous animals have longer intestines than that of carnivorous animals. This is because their diet is grass and plants, made up of fibre and cellulose which are hard to digest. As a result, the herbivorous animals need a longer digestive track to digest their foods completely.

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When a DNA solution is heated enough, the double-stranded DNA unwinds, and the Hydrogen bonds that hold the two strands together weaken and finally break. The process of breaking a double-stranded DNA into single strands is known as DNA denaturation, or DNA melting. The hyper-chromicity of DNA occurs when the DNA duplex is denatured.

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A seed can germinate in the absence of adequate light. It’s only photoblastic seeds which need light exposure for germination such lettuce, maize, etc. Small seeds generally germinate better in light than in darkness, while large seeds do not exhibit a difference in germination between these two conditions (Milberg et al. 2000. 2000. Large seeded species are less dependent on light for germination than small-seeded ones.

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The chromosomes which determine the sex (maleness or femaleness) of an individual in sexually producing organisms are called sex chromosomes or allosomes. In humans an individual whose cells contain XX chromosomes (homo or isogametic) becomes a female, while one whose cells contains XY chromosomes (heterogametic) becomes a male.

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Gymnosperm are flowerless plant that produces cones and seeds. The term gymnosperm literally means “naked seed”, as gymnosperm seed are not encased within an ovary. Rather they sit exposed on the surface of the leaf like structures called bracts.

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The cerebellum is important for making postural adjustments in order to maintain balance. Through its input from vestibular receptors and proprioceptors, it modulates commands to motor neurons to compensate for shifts in body position or changes in load upon muscles. So, it controls the maintenance of posture, balance and equilibrium.

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The first observations of intracellular structures that probably represented mitochondria were published in the 1840s. Richard Altmann, in 1890, established them as cell organelles and called them “bioblasts”. The term “mitochondria” was coined by German microbiologist Carl Benda in 1898.

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An allele is one of a pair of genes that appear at a particular location on a particular chromosome and control the same characteristic, such as blood type or colorblindness. Alleles are also called alleleomorphs. If the two alleles are identical, the individual is called a homozygote; when the two alleles are different, the individual is a heterozygote.