Answer :
Unicellular organisms are single celled organisms while multicellular organisms are many celled organisms.
Small cell organisms have more particles then a big cell with less particles simply because materials are easily transported through them due to their surface area to volume ratio.
In order words, a small cell has a surface area to volume ratio which is capable of carrying more particles than a bigger cell.
What are unicellular and multicellular organisms?
Unicellular organisms are those living organisms consisting of only one cell.
Multicellular organisms are organisms which consist of more than one cell.
Bacteria is one of few examples unicellular organisms.
Some few examples of multicellular organisms are: lizard, fishes, crocodile and so on and so forth.
So therefore, unicellular organisms are single celled organisms while multicellular organisms are many celled organisms. Also, a small cell has a surface area to volume ratio which is capable of carrying more particles than a bigger cell.
Learn more about unicellular organisms:
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