Distinguish between homologous organs and analogous organs. In which category would you place wings of a bird and wings of a bat ? Justify your answer giving a suitable reason.

Q: Distinguish between homologous organs and analogous organs. In which category would you place wings of a bird and wings of a bat ? Justify your answer giving a suitable reason.

### 1. Distinction between Homologous and Analogous Organs | Feature | Homologous Organs | Analogous Organs | | :--- | :--- | :--- | | **Basic Structure & Origin** | They have a **similar** basic structural design and developmental origin. | They have **different** basic structural designs and developmental origins. | | **Function** | They perform **different** functions in different organisms. | They perform **similar** functions in different organisms. | | **Evolutionary Significance** | They indicate **common ancestry** (divergent evolution). | They do not indicate common ancestry; they show adaptation to a similar environment (**convergent evolution**). | | **Example** | Forelimbs of a human and forelimbs of a frog. | Wings of an insect and wings of a bird. | --- ### 2. Classification of Wings of a Bird and Wings of a Bat The wings of a bird and the wings of a bat are placed in the category of **Analogous Organs** (when compared specifically as organs of flight). #### **Justification:** * **Different Basic Structure and Origin:** * A **bat's wing** consists of a fold of skin (patagium) stretched mainly between greatly elongated fingers. * A **bird's wing** consists of a bony support covered with feathers all along the arm. * This shows that their designs, structures, and components are very different, meaning they did not inherit their wing design from a common ancestor with wings. * **Same Function:** Despite their different structural designs, both organs are adapted to perform the same function, which is **flying**. *(Note: If we look at them as forelimbs rather than wings, their skeletal structures are homologous, but as organs of flight, they are analogous.)*

Heredity

Homologous and Analogous Organs

Official Answer

1. Distinction between Homologous and Analogous Organs

Feature	Homologous Organs	Analogous Organs
Basic Structure & Origin	They have a similar basic structural design and developmental origin.	They have different basic structural designs and developmental origins.
Function	They perform different functions in different organisms.	They perform similar functions in different organisms.
Evolutionary Significance	They indicate common ancestry (divergent evolution).	They do not indicate common ancestry; they show adaptation to a similar environment (convergent evolution).
Example	Forelimbs of a human and forelimbs of a frog.	Wings of an insect and wings of a bird.

2. Classification of Wings of a Bird and Wings of a Bat

The wings of a bird and the wings of a bat are placed in the category of Analogous Organs (when compared specifically as organs of flight).

#### Justification:

Different Basic Structure and Origin:
A bat's wing consists of a fold of skin (patagium) stretched mainly between greatly elongated fingers.
A bird's wing consists of a bony support covered with feathers all along the arm.
This shows that their designs, structures, and components are very different, meaning they did not inherit their wing design from a common ancestor with wings.
Same Function: Despite their different structural designs, both organs are adapted to perform the same function, which is flying.

(Note: If we look at them as forelimbs rather than wings, their skeletal structures are homologous, but as organs of flight, they are analogous.)

homologousanalogousbasic structureoriginfunctionskin foldsfeathersflying

Marking Scheme

1Distinction between homologous and analogous organs (with 1-2 points): 1 Mark
2Correct categorization of wings of a bird and wings of a bat as analogous organs: 1 Mark
3Suitable justification based on structural differences and functional similarity: 1 Mark

Hint

Focus on the structural design of the wings (feathers vs. skin folds) and their common function (flying) to determine their category.

Quick Oral Answer

Homologous organs have the same basic structure but different functions, like the forelimbs of a human and a frog. Analogous organs have different structures but perform the same function, like the wings of a butterfly and a bird.

Analysis & Explanation

This question tests the student's understanding of evolutionary relationships through anatomical evidence.

Homology vs. Analogy: Homologous organs point to divergent evolution (sharing a common ancestor but adapting to different niches), while analogous organs point to convergent evolution (different ancestors adapting to similar niches/functions).
The Bird vs. Bat Wing Dilemma: This is a classic conceptual checkpoint. At the level of the integumentary/flight structure (feathers vs. skin folds), they are analogous because they evolved flight independently. However, at the level of the skeletal system (humerus, radius, ulna, carpals), they are homologous because both inherited their tetrapod limb structure from a common ancestor. For CBSE Class 10, classifying them as analogous organs with respect to flight is the standard expected answer.

Common Mistakes

1Students often confuse homologous and analogous organs.
2Many students classify wings of birds and bats as homologous because they are both forelimbs, but as wings (organs of flight), they are analogous because their flight structures evolved independently.

Interesting Facts

While the wings of birds and bats are analogous as flight structures, their skeletal forelimbs are homologous, showing that evolution can work on different levels simultaneously!

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2012?

This question carries 3 marks in the CBSE Class 10 Science 2012 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 "Homologous and Analogous Organs" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2012 paper?

This is a Short Answer question from Section A in the CBSE Class 10 Science 2012 paper.