Page 82 - Biology - XII

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Analogous Organs (ana—means diff erent)
1. These are organs that are anatomically dissimilar in structure, but have similarities in the functions
they perform.
2. They are the result of convergent evolution.
3. In plants, the stem of potato and the root of sweet potato are underground modifi cations. They are
diff erent structurally, but perform a similar function, i.e. storage of food.
4. In animals, wings of an insect and a bird are result of convergent evolution and they perform a similar
function, that is, fl ying. But they are anatomically diff erent.

Flower Leaf
Potato plant

Fruit

Potato
Stem
Roots
Eyes

Tuber
Tuber
Roots
(a) (b)

Fig. 15.1: Analogous organs in plants

(a) Bat wing (b) Bird wing (c) Insect wings

Fig. 15.2: Analogous organs in animals

Homologous Organs (Homo—means similar)

1. These are the organs that have similar anatomical
structures, but perform various functions.
2. They are a result of divergent evolution. Tendril
3. In plants, tendrils of Cucurbits and thorns of
Bougainvillea are examples of homologous
organs performing diff erent functions. Thorn
4. In animals, the wings of bats, the forearms of humans,
and the legs of cheetahs have similar anatomical (b) Cucurbita
structures, but perform diff erent functions like fl ying, (a) Bougainvillea
walking, and running, respectively. Fig. 15.3: Homologous organs in plants
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