GENERAL ANATOMY
EMBRYOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The bones of all animals are similarly arranged.
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The bones of animals that take in oxygen are similarly arranged.
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Humans and whales use these structures to perform the same functions.
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Humans and whales inherited these structures from a common ancestor.
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Detailed explanation-1: -If two or more species share a unique physical trait they may all have inherited this trait from a common ancestor. Traits that are shared due to common ancestry are homologous structures. The similar bone arrangement of the human, bird, and whale forelimb is a structural homology.
Detailed explanation-2: -Limbs. Cetacean flippers have the same bones as the forelimbs of other mammals. The humerus, radius, ulna, carpals, metacarpals and phalanges are all present. However, in cetaceans the radius and ulna (forearm) and humerus (upper arm) are fused.
Detailed explanation-3: -Whales, lizards, humans, and birds all have the same basic limb layout. But how did such different animals wind up with the same sort of limb? The answer is that they inherited it from a common ancestor, just as cousins might inherit the same trait from their grandfather.
Detailed explanation-4: -A whale flipper and a bat wing are also homologous structures in the same sense as a human arm and cat arm with a humerus, radius and ulna, and so on.
Detailed explanation-5: -Under the skin of the whale’s flipper is a skeleton that’s eerily-similar to a human hand. The structure is called a “pentadactyl limb”, and despite the weirdness of it, it’s actually a familiar occurrence in many animals.