Multiple choice

The need of tissues in multicellular organisms arises due to ______.

  1. increase in the size of cells

  2. increase in the size of body

  3. increase in the movements of body

  4. increase in the structure of body
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Multicellular organisms develop a complex body structure and the cells are not exposed for long time to the air or water media for exchange of materials. Hence, specialized tissues become necessary to reach all the cells and do the needful activities like gaseous exchange, supply of food, removal of excretory products from all the cells. For this, cells do not increase in size; they are only more in number. Movements increase as a result of efficient working of tissues. Further, there are many multicellular organisms, which are small or minute in size. Hence, tissues are basis of structure and not size. 

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