Why do organisms molt their exoskeleton and grow new ones periodically? What will be an ideal ...

Answer to q. 1

An exoskeleton consists of noncellular secreted material, so it cannot grow with the animal. As an organism grows, it must periodically molt its old skeleton and replace it with a larger one.

Answer to q. 2

By one hypothesis, the common ancestor of animals and choanoflagellates was a single-celled protist with adhesion proteins that helped it capture prey. Later, these proteins were put to use in a new context, helping choanoflagellates stick together to form multicelled colonies. Later still, the proteins allowed animal cells to adhere to one another in multicelled bodies. This modification in the use of adhesion proteins is an example of exaptation, an evolutionary process by which a trait that evolves with one function later takes on a different function.

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