Explain how evolutionary relationships can be traced by the study of homologous organs.
Explain how evolutionary relationships can be traced by the study of homologous organs.
Evolutionary relationships are traced by identifying characteristics that are similar in different organisms. According to the text, inheritance from previous generations provides a 'common basic body design' along with subtle changes. Homologous organs are those that share a similar basic structural design and origin, even if they perform different functions in different species. The presence of such common designs suggests that these organisms have inherited them from a common ancestor. By studying these structural similarities, scientists can determine how closely related different species are and trace their evolutionary history back to a shared point of origin.
Marking Scheme
- 1Definition of tracing relationships through common basic body design. (1 mark)
- 2Explanation that similarity in structure (homology) indicates common ancestry. (1 mark)
- 3Mentioning that variations/subtle changes occur over generations while maintaining the basic design. (1 mark)
Hint
Think about what a 'common basic body design' implies about the ancestors of different species.
Quick Oral Answer
We trace evolutionary relationships by looking for homologous organs, which are structures that share a common basic body design inherited from a common ancestor, even if they serve different purposes now.
Analysis & Explanation
The text mentions that 'Inheritance from the previous generation provides both a common basic body design, and subtle changes in it'. This concept is the basis for understanding homologous organs. While the specific term 'homologous' is often detailed in the evolution sub-section, the provided text establishes that similarities in body design are inherited. If two different species show a similar fundamental structure (like the limb bones of mammals), it implies they share a common ancestor who possessed that basic design, which then underwent 'subtle changes' or modifications over generations to suit different environments.
Common Mistakes
- 1Confusing homologous organs (same structure, different function) with analogous organs (different structure, same function).
- 2Assuming that similar functions always mean a close evolutionary relationship.
Interesting Facts
The basic bone structure of a whale's flipper, a bat's wing, and a human arm is remarkably similar, despite their very different uses.
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2011?
This question carries 3 marks in the CBSE Class 10 Science 2011 examination.
Which chapter does this question come from in Science?
This question is from the chapter "Heredity" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Evolutionary Relationships" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2011 paper?
This is a Short Answer question from Section A in the CBSE Class 10 Science 2011 paper.