Biology MCQs

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Alec Jeffreys scientists is known for developing techniques for DNA fingerprinting and DNA profiling which are now used all over the world in forensic science to assist police detective work.

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In biology, a taxon (plural taxa; back-formation from taxonomy) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit.

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As cells develop some genes are turned off permanently. All of the cells within a complex multicellular organism such as a human being contain the same DNA; however, the body of such an organism is clearly composed of many different types of cells. What, then, makes a liver cell different from a skin or muscle cell? The answer lies in the way each cell deploys its genome. In other words, the particular combination of genes that are turned on (expressed) or turned off (repressed) dictates cellular morphology (shape) and function. This process of gene expression is regulated by cues from both within and outside cells, and the interplay between these cues and the genome affects essentially all processes that occur during embryonic development and adult life. This means that cells become specialized because the genes that are not required are switched off. Only the genes needed to make a particular type of cell work are switched on. So muscle cells only have the genes needed to make muscle cell proteins switched on. All the other genes, such as those needed to make blood cell proteins and nerve cell proteins, are switched off. But the stem cells are unspecialized and can develop into various tissues.

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Cattle quickly swallow grass and store it in rumen. The rumen serves as a large fermentation vat in which bacteria and other microorganisms reside. The rumen, also known as a paunch, forms the larger part of the reticulorumen

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Night blindness is caused by nearsightedness, cataracts, or vitamin A deficiency. Night blindness (nyctalopia) is the inability to see well at night or in poor light. Its causes include glaucoma medications and cataracts

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Darwinism is a theory of biological evolution developed by the English naturalist Charles Darwin. All species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual’s ability to compete, survive, and reproduce.
Darwin’s evolutionary theory of natural selection gave a more rational explanation of the formation of new species. As per natural selection, various species originated from a single species as a result of adaptation to the changing environment.
Natural selection takes place in four different ways as follows:
• Variation – The changes accumulated over a period of time in an organism usually gives rise to a new species.
• Inheritance – It is the passing on of the variations over generations which ultimately lead to speciation.
• A high rate of growth of population – This gives rise to more number of organisms being reproduced by a species than the environment can support which might lead to the extinction of that particular species.
• Differential survival and reproduction – The superior variations lead to survival of a particular organism and the inferior or negative variation leads to extinction. The superior variations are the ones inherited during reproduction.

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Rickets is a skeletal disorder that’s caused by a lack of vitamin D, calcium, or phosphate. These nutrients are important for the development of strong, healthy bones. People with rickets may have weak and soft bones, stunted growth, and, in severe cases, skeletal deformities.

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The sensation of fatigue which the muscles feel after a prolonged and a strenuous physical workout is caused by the accumulation of lactic acid.
This is so because lactic acid buildup tends to cause fatigue and soreness in the muscles.
There is a burning sensation felt up in the muscles when buildup of acid happens in muscles during exercise. This is also known as acidosis.

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The person with O-ve blood group is considered as the universal donor. Whereas a person with O +ve is not a universal donor as O +ve consists of Rh(Rhesus) factor  which makes it incompatible for Rh -ve bloods.

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Rickets is a disease related to bone disorder due to the deficiency of vitamin D. Vitamin D is a fat soluble vitamin. Vitamin D is also called as calciferol. Lack of calcium also leads to rickets.