Q.What conclusion can be drawn if the forelimbs of an aquatic animal and a terrestrial animal have similar anatomical structure ? (A) Live in same habitat (B) Share common ancestors (C) Forelimbs perform same functions (D) Forelimbs are analogous
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Start your 14-day free trial to unlock the full solution →Similar anatomical structures in the forelimbs of different animals, despite varied functions and habitats, indicate that they share a common ancestor.
When we observe the natural world, one of the most fascinating aspects is the diversity of life, yet beneath this diversity, there are often striking similarities. The question of why different animals, living in vastly different environments and performing different tasks, might possess forelimbs with a fundamentally similar anatomical structure is central to understanding evolutionary biology. This observation provides powerful evidence for how life on Earth has changed over millions of years.
Consider the forelimb of a whale, an aquatic mammal, and the forelimb of a human, a terrestrial mammal. Superficially, they look very different: a whale's flipper is adapted for swimming, while a human's arm is adapted for grasping, manipulating, and walking (in our distant ancestors). However, if we examine their internal bone structure, we find a remarkable resemblance. Both possess a humerus (upper arm bone), radius and ulna (forearm bones), carpals (wrist bones), metacarpals (palm bones), and phalanges (finger bones), arranged in a very similar pattern.
Structures that have the same basic structural plan but perform different functions are called homologous structures. They are a key piece of evidence for evolution.
This similarity in basic anatomical structure, despite differences in function and habitat, is not a coincidence. It suggests that these animals inherited this fundamental limb design from a common ancestor. Over vast periods, as different groups of descendants adapted to various environments and lifestyles—some returning to water, others remaining on land—their forelimbs underwent modifications. These modifications allowed them to perform specialized functions like swimming, flying, running, or grasping, but the underlying blueprint remained. This process, where structures diverge from a common form to serve different functions, is known as divergent evolution.
Let's evaluate the given options based on this understanding:
- ** (A) Live in same habitat:** This is incorrect. The premise of the question explicitly states an aquatic animal and a terrestrial animal, meaning they live in different habitats.
- ** (C) Forelimbs perform same functions:** This is also incorrect. A whale's flipper is for swimming, while a human's arm is for grasping and manipulating. Their functions are distinct, even if both involve movement. …
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