General Science Questions (MCQs) for Competitive Examinations

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Root hairs are tubular-shaped tip-growing cells that arise from epidermal cells known as trichoblasts, behind the tips of young roots. Like all tip-growing cells, root hairs grow by the addition of cell wall precursors to the tip delivered by vesicles from the endomembrane system.

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Some plants have the stem branching out near the base. The stem is hard but not thick. Such plants are called shrubs. Eg: Rose plant. Shrubs have persistent woody stems above the field, unlike herbaceous plants. Shrubs may be evergreen or deciduous. By their numerous stems and shorter height, less than 6 m-10 m long, they are distinguished from trees.

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Buccal cavity (oral cavity) refers to the mouth cavity: the beginning of the alimentary canal, which leads to the pharynx and (in vertebrates) to the oesophagus. It is part of the digestive system. In mammals it contains the tongue and teeth, which assist in the mechanical breakdown of food, and the openings of the salivary glands.

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Bulbil is a small bulblike organ of vegetative reproduction growing in leaf axils or on flower stalks of plants such as the onion and tiger lily. It is a reproductive organ that takes part in vegetative reproduction. The bulbils drop from the parent plant on to the ground, give out adventitious roots and develop into new plants. The other structures involved in vegetative propagation include rhizome, bulb, corm, cuttings, etc.

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Insect and bird wings are analogous structures but not homologous structures. They are externally similar in appearance and function (i.e. for flying), but have dissimilar origin and developmental plan.

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Cod is the common name for the genus Gadus of demersal fishes, belonging to the family Gadidae. Cod is also used as part of the commons name for a number of other fishes, and there are species suggested to belong to genus Gadus that are not called cod (the Alaska pollock). Cod is popular as a food with a mild flavour and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of vitamin A, vitamin D, vitamin E and omega-3 fatty acids (EPA and DHA).

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Aflatoxin are naturally occurring mycotoxins that are produced by Aspergillus flavus and Aspergillus parasiticus, species of fungi. They have been associated with various diseases, such as aflatoxicosis, in livestock, domestic animals and humans throughout the world.

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Yeast is an important source of most B vitamins (except B12) and folate and contains potassium and magnesium. It is used in the preparation of vitamin B complex tablets. Therefore, seeds have been classified as endospermic with endosperm and nonendospermis without endosperm.

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Wilhelm Johannsen was a Danish botanist, plant physiologist and geneticist. His most well-known research concerned so-called pure lines of the self-fertile common bean. He was able to show that even in populations homozygous for all traits, i.e. without genetic variation, seed size followed a normal distribution. This was attributable to resource provision to the mother plant and to the position of seeds in pods and of pods on the plant. This led him to coin the terms phenotype and genotype and introduce the term gene. This term was coined in opposition to the then common pangene that stemmed from Darwin’s theory of pangenesis.

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Sarpagandha plant is used to treat blood pressure. It’s one of the major source of resperine. The powder derived from Sarpagandha roots is an excellent natural remedy for treating hypertension. Sarpagandha lowers blood pressure and improves blood circulation by dilating the blood vessels and controlling nerve function in the muscles that lead to the heart.