(a) Classify the following as homologous or analogous pairs:

(i) Broccoli and Cabbage

(ii) Ginger and Raddish

(iii) Fore limbs of birds and lizard

(iv) Wings of a bat and Wings of a bird

(b) State the main feature that categorises a given pair of organs as homologous or analogous.

Q: (a) Classify the following as homologous or analogous pairs: (i) Broccoli and Cabbage (ii) Ginger and Raddish (iii) Fore limbs of birds and lizard (iv) Wings of a bat and Wings of a bird (b) State the main feature that categorises a given pair of organs as homologous or analogous.

(a) **Classification of the given pairs:** * **(i) Broccoli and Cabbage:** **Homologous structures** (Both are derived from a common ancestor, the wild cabbage, through artificial selection, representing a common evolutionary origin but modified for different features). * **(ii) Ginger and Radish:** **Analogous structures** (Ginger is a modified underground stem while radish is a modified root. Both perform the function of food storage but have different structural origins). * **(iii) Fore limbs of birds and lizard:** **Homologous structures** (They share a similar basic skeletal/anatomical design inherited from a common ancestor, but perform different functions like flying and walking/crawling). * **(iv) Wings of a bat and Wings of a bird:** **Analogous structures** (They perform the same function of flight but have different basic structural designs and origins; a bat's wing consists of skin folds stretched between elongated fingers, whereas a bird's wing is supported by feathers along the entire arm). (b) **Main categorising features:** * **Homologous Organs:** Organs that share a **common basic structural design and developmental origin** but perform **different functions** in different organisms. * **Analogous Organs:** Organs that have **different basic structural designs and origins** but perform **similar functions** due to adaptation to a similar environment or lifestyle.

Heredity

Homologous and Analogous Organs

Official Answer

(a) Classification of the given pairs:

(i) Broccoli and Cabbage: Homologous structures (Both are derived from a common ancestor, the wild cabbage, through artificial selection, representing a common evolutionary origin but modified for different features).
(ii) Ginger and Radish: Analogous structures (Ginger is a modified underground stem while radish is a modified root. Both perform the function of food storage but have different structural origins).
(iii) Fore limbs of birds and lizard: Homologous structures (They share a similar basic skeletal/anatomical design inherited from a common ancestor, but perform different functions like flying and walking/crawling).
(iv) Wings of a bat and Wings of a bird: Analogous structures (They perform the same function of flight but have different basic structural designs and origins; a bat's wing consists of skin folds stretched between elongated fingers, whereas a bird's wing is supported by feathers along the entire arm).

(b) Main categorising features:

Homologous Organs: Organs that share a common basic structural design and developmental origin but perform different functions in different organisms.
Analogous Organs: Organs that have different basic structural designs and origins but perform similar functions due to adaptation to a similar environment or lifestyle.

HomologousAnalogousCommon originBasic structural designDifferent functionsSimilar functionsWild cabbageModified stemModified root

Marking Scheme

1Correct classification of all four pairs (i to iv) as homologous or analogous (2 marks)
2Clear definition/feature of homologous organs (same structure/origin, different functions) (0.5 marks)
3Clear definition/feature of analogous organs (different structure/origin, same function) (0.5 marks)

Hint

Identify whether the organs share the same anatomical origin (like stem vs. root, or shared vertebrate limb bones) or if they only share a common function (like food storage or flying).

Quick Oral Answer

Homologous organs are those that have a similar basic structure and origin but perform different functions, such as the forelimbs of a bird and a lizard. Analogous organs have different structures and origins but perform the same function, like the wings of a bat and a bird.

Analysis & Explanation

Homology indicates common ancestry (divergent evolution), where the internal anatomy is similar even if the external appearance and function differ. Analogy indicates adaptation to similar functional requirements (convergent evolution), where the structures look similar and perform the same function but have completely different anatomical origins (e.g., ginger is stem tissue, radish is root tissue; bat wings are skin membranes, bird wings are feathered limbs).

Common Mistakes

1Classifying wings of a bat and wings of a bird as homologous because they both help in flying. In reality, their anatomical structures are completely different, making them analogous.
2Confusing ginger (stem) and radish (root) as homologous because they are both underground food-storing parts.

Interesting Facts

Though bats and birds both fly, their wings evolved independently. The common ancestor of bats and birds was a four-legged terrestrial tetrapod that did not fly, meaning their limbs are homologous as forelimbs, but analogous as wings!

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2020?

This question carries 3 marks in the CBSE Class 10 Science 2020 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 2020 paper?

This is a Short Answer question from Section B in the CBSE Class 10 Science 2020 paper.