To analyze:
Why the evolution of multicellular organisms has led to the development of circulatory systems.
Introduction:
A circulatory system is responsible for transport of various substances through the body of the organism. There are various types of circulatory systems.
Explanation of Solution
Cells in a multicellular organism are not in direct contact with the external environment. This means that the exchange of gases, uptake of nutrients, expulsion of wastes and other such processes cannot be carried out in a simple, straightforward way. Simple diffusion, like in the case of unicellular organisms, is not enough to perform these functions. Dedicated delivery and waste removal systems became necessary. This is the reason for the development of the circulatory systems.
In multicellular organisms, most of the cells of an organism are not in direct contact with the external environment. Diffusion cannot adequately transport essential nutrients and wastes into and out of the cells. A dedicated delivery and removal system became necessary, and this led to the development of circulatory systems.
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Chapter 21 Solutions
What is Life? A Guide to Biology with Physiology
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