Studying homology and analogy with the help of models/charts of animals and models/charts/specimens of plants
To study homology and analogy with the help of models/charts of animals and models specimens of plants.
Plant specimens such as Bougainvillea, cucurbits, potato and sweet potato. Animal models like bird, butterfly, forelimb of frog.
Homologous organs: The organs which perform different functions in different species but have similar basic structure and similar embryonic origin are called homologous organs.
Analogous organs: The organs which are quiet different in fundamental structure and embryonic origin but perform same function and may superficially look alike in entirely different species are called analogous organs.
- Take the specimens/models/charts and observe them carefully.
- Record the structure and function of each specimen.
- Draw their neat and labelled diagrams.
A. Tendrils of cucurbits and spines of Bougainvillea
- Tendrils of cucurbits are modified stem which are used to climb a support.
- Spines of Bougainvillea are modified stem which are meant for protection.
- Both tendril of cucurbits and spines of Bougainvillea have same basic structural design but perform different functions. So, they are homologous organs.
B. Forelimb of frog and forelimb of bird
- The forelimb of frog consists of upper arm, fore arm, wrist, palm and five fingers. The upper arm is having humerus, fore arm with radius and ulna, wrist with carpels, palm have metacarpels and fingers have phalanges. The forelimb of frog helps the animal to prop up the front end of the body at rest and acts as a shock absorber when the animal lands on the ground after a leap.
- The forelimb of birds also has same basic plan of structure with an upper arm having humerus, a fore arm with radius and ulna, a wrist with carpels, a palm with metacarpels and five fingers with phalanges. The forelimb of the bird helps in flying.
- Both forelimbs of frog and bird show sinilarity in basic structure but perform entirely different function. So, they are homologous organs.
C. Potato and sweet potato
- In potato, eyes are present which are actually nodes.
- Potato is a modified stem which is adapted to store the food.
- Sweet potato is a modified root which is meant for storage of food.
- Both potato and sweet potato are structurally different but they perform the same function, i.e., storage food. So, they are analogous organs.
D. Wings of butterfly and wings of bird
- The wings of butterfly are extensions of integuments which are supported by a few muscles and used for flying in the air.
- The wings of birds are formed of limb bones covered with flesh, skin and feathers. Birds also use their wings for flying.
- Both wings of butterfly and wings of birds are structurally different but they perform the same function. So, they are anologous organs.
Result And Discussion
- Homologous organs have same structure but are functionally different.
- Analogous organs have same function but are structurally different.
- The specimens should be fresh and clean.
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