General Science Questions (MCQs) for Competitive Examinations

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A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The pulmonary arteries are unique in that unlike most arteries which carry oxygenated blood to other parts of the body, the pulmonary arteries carry de-oxygenated blood to the lungs. After picking up oxygen, the oxygen rich blood is returned to the heart via the pulmonary veins.

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Mostly medicinal herbs grown from 30 to 90 cm in height. They reach up to 30 cm in diameter.

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According to the K+ ion theory the guard cells absorb K+ ions from the cells around them as they produce ATP (due to photosynthesis) and become hypertonic. This leads to absorption of water from nearby cells by endosmosis due to which the guard cells become turgid and the stomata opens. Decreasing light intensity and photosynthesis causes Stomatal closing.

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Myxine is a species of jawless fish (Agnatha). It is known as Hag fish in Europe. These are generally classified with the lampreys into the superclass Agnatha (jawless vertebrates) within the subphylum Vertebrata. All other living fishes (shark, rays, chimeras and bony fishes) possess true jaws derived from gill arches and are placed in the superclass Gnathostomata.

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Microorganisms or decomposers such as bacteria and fungi help in the process of recycling of nutrients by decomposing various dead organisms such as plants and animals to form humus. Humus is highly nutritious and rich in minerals and microbes vital for healthy plant growth.

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The majority of the upper respiratory epithelium is lined with cilia, small hair-like structures that move together like oars to push the mucus and its trapped contents to the throat, where it is swallowed. Each cell has about 300 cilia.

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Dengue virus is the cause of dengue fever. Dengue virus is transmitted by female mosquitoes mainly of the species Aedes aegypti and, to a lesser extent, Ae. albopictus. This mosquito also transmits chikungunya, yellow fever and Zika infection. Dengue is widespread throughout the tropics, with local variations in risk influenced by rainfall, temperature and unplanned rapid urbanization.

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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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The constituents of phloem are Sieve tubes, Companion cells, Phloem parenchyma, Phloem fibres. Tracheids are elongated cells in the xylem of vascular plants that serve in the transport of water and mineral salts. These are elongated narrow tube like cells with hard thick and lignified walls with large cell cavity.

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Deciduous means “falling off at maturity” or “tending to fall off”. Deciduous trees or shrubs lose their leaves seasonally. The converse of deciduous is evergreen.