Question

1. why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like human?
2. what criteria do we use to decide whether something is alive?
3. what are outside raw materials used for by an organisms?

Answer 1

1.Diffusion is insufficient because in unicellular organisms full body surface is in contact with environment. Hence diffusion is sufficient for such animals . In multicellular organisms, the complexity of animals is more and diffusion is a slow process's. Hence diffusion is insufficient.

Answer 2

Diffusion is Insufficientto meet the oxygen requirements in multicellular organisms because multicellular organisms such as human beings have Complex body design and large body size does the bear specialised cells and tissues for performing various necessary functions of the body such as intake of food and oxygen etc .Unlike unicellular organisms multicellular organism do not have all the cells of the body in direct contact with the environment hands diffusion cannot meet the oxygen requirements..
2- visible movements like green colour of plants ,running of animals or growth, molecular movements acts as the main criteria to decide whether something is alive or not.
3- carbon based molecules that is food is used by body from outside to meet its energy needs oxygen is used to outside Food and release energy. So, food and oxygen are the basic raw material used by an organism.

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