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Heredity and Evolution — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceHeredity and Evolution3 Marks
Question
What are homologous structures? Give an example. Is it necessary that homologous structures always have a common ancestor. Justify your answer.
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Answer

Structures which have a common basic structure but perform different functions are called homologous structures.For example: Forelimbs of mammals, birds, reptiles and amphibians.
The forelimbs of humans and the wings of birds perform different functions, but their skeletal structures are similar.Yes, homology indicates common ancestry. Homologous organs follow the same basic plan of the organisation during their development but in the adult condition, these organs are modified to perform different functions as an adaptation to different environments.

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