General Science Questions (MCQs) for Competitive Examinations

Notes:
Damping off is a horticultural disease or condition, caused by a number of different pathogens that kill or weaken seeds or seedlings before or after they germinate. Pythium, a genus of parasitic oomycete, are most often responsible for damping-off. Along with Rhizoctonia solani, attacks by Pythium are most associated with producing roughly circular patches of dead seedlings.

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Anaemia is a condition that develops when blood lacks enough healthy red blood cells or haemoglobin. The three main types of Anaemia are due to blood loss, decreased red blood cell production, and increased red blood cell breakdown. Causes of decreased production include iron deficiency, a lack of vitamin B12, thalassemia, and a number of neoplasms of the bone marrow.

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Femur (thighbone) the longest bone in human body. Its average length is 19.9 inch. The femur is the only bone in the thigh. Tibia (shin bone) and Fibula (lower leg) come next in sequence with length of 16.9 and 15.9 inch respectively.

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The International Commission on Zoological Nomenclature (ICZN) was founded in 1895. It provides and regulates a uniform system of zoological nomenclature ensuring that every animal has a unique and universally accepted scientific name.

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Eutrophication is the ecosystem response to the addition of artificial or natural substances, such as nitrates and phosphates, through fertilizers or sewage. It leads not only to increased levels of nutrients, but increased Biological Oxygen Demand as well following the decay of algal bloom in stagnant water reservoirs.

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Bonsai is the art of aesthetic miniaturization of trees and plants in containers. A bonsai plant is not a dwarf plant but equal to the full sized flowering plant. The main objective of bonsai plants is to create a tree or plant, and even landscapes, in miniature at household level.

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Robert Harding Whittaker was a distinguished American plant ecologist who was the first to pro pose the five-kingdom taxonomic classification of the world’s biota into the Animalia, Plantae, Fungi, Protista, and Monera in 1969. He also proposed the Whittaker Biome Classification, which categorized biome-types upon two abiotic factors: temperature and precipitation.

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Fertilization in plants is not directly influenced by sunlight. Fertilization occurs after pollination, when pollen grains land on the stigma of a flower of the same species. During this time, a series of events take place leading to the formation of seeds. However, none of these event is affected by presence or absence of light.

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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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Bioremediation is a waste management technique that involves the use of organisms to remove or neutralize pollutants from a contaminated site. It uses naturally occurring organisms to break down hazardous substances into less toxic or non-toxic substances. There are two classes of bioremediation used : In situ and Ex situ.