Origin and Evolution of Life — Science STD 10 — Question
Tamilnadu BoardEnglish MediumSTD 10ScienceOrigin and Evolution of Life2 Marks
Question
Explain the types of variation?
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Answer
Variations are the differences found among individuals of the same species and the offspring of the same parent. New species originate by the gradual accumulation of variations. Evolution would not be possible without variation. Somatic variation and germinal variation are the two types of variations:
Somatic variation: The variation which affects the body (somatic) cells of the organisms are called somatic variation, which is not heritable. They occur due to environmental factors.
Geminal variation: The variations, which are produced in germ cells and inherited are called germinal variation. They are classified into two types.
Continuous variation: Small variations which occur among individuals of a population, and occur by gradual accumulation is called continuous variation. They are also called fluctuating variation, e.g. skin colour, height and weight and colour of the eye, etc.
Discontinuous variation: These changes are sudden, which occur in an organism, due to mutations. These large variations are not useful for evolution, e.g. short – legged Ancon sheep and six or more digits (fingers) in human, etc.
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