Find out the odd one out among the following structures in relation t…

The correct answer is Option (4) → Thorns of Bougainvillea and tendrils of Cucurbita

Homologous organs have the same basic structure and origin but do different jobs; they show divergent evolution and common ancestry. Analogous organs do the same job but differ in structure and origin; they show convergent evolution under similar habitats.

Option (1) Sweet potato and potato — Analogous. Both store food, but sweet potato is a root and potato a stem.

Option (2) Penguin and Dolphin flippers — Analogous. Both help in swimming, but a bird and a mammal evolved them separately.

Option (3) Mammals and Octopus Eyes — Analogous. Both see, but the eye of a mollusc and of a mammal arose separately.

Option (4) Thorns of Bougainvillea and tendrils of Cucurbita — Homologous, the odd one out. Both are modified stems (axillary in origin) doing different jobs: protection and climbing.

NCERT Extract:
What Are the Evidences for Evolution? – “… This is divergent evolution and these structures are homologous. Homology indicates common ancestry. Other examples are vertebrate hearts or brains. In plants also, the thorn and tendrils of Bougainvillea and Cucurbita represent homology (Figure 6.3a). Homology is based on divergent evolution whereas analogy refers to a situation exactly opposite. Wings of butterfly and of birds look alike. They are not anatomically similar structures though they perform similar functions. Hence, analogous structures are a result of convergent evolution - different structures evolving for the same function and hence having similarity. Other examples of analogy are the eye of the octopus and of mammals or the flippers of Penguins and Dolphins. One can say that it is the similar habitat that has resulted in selection of similar adaptive features in different groups of organisms but toward the same function: Sweet potato (root modification) and potato (stem modification) is another example for analogy.”

Figure 6.3 Example of homologous organs in (a) Plants and (b) Animals