ANATOMY

Detailed explanation-1: -Multicellular organisms need communication systems in order to coordinate the different organs in the body and maintain homeostasis. Multicellular organisms are made of sometimes up to billions of cells.

Detailed explanation-2: -Chemical communication is very important in multicellular organisms. Chemical communication takes place with the help of chemical messengers called hormones. These hormones are synthesised in one part of the body and reach to target site which is located far away.

Detailed explanation-3: -In multicellular organisms, cells constantly send and receive chemical messages to coordinate the actions of other organs, tissues, and cells. The ability to send messages quickly and efficiently enables cells to coordinate and fine-tune their functions.

Detailed explanation-4: -Bacteria and arachaea are unicellular and lack a nucleus.