How big do unicellular organisms grow?
As big as amoeba and plasmodium can grow.
The advantage of a multicellular organism over a unicellular organism is that multicellular organisms can grow to virtually any size because the cells integrate their activities and are permanently associated with one another. Unicellular organisms can only grow to a certain size because of certain surface-area-to-volume problems Multicellular organisms have specialization
Unicellular organisms meet their basic needs by metabolism (eating, drinking, breathe, and excrete) , growth (how big do they grow), Reproduction, irritability (how do they react to heat and cold, how do they react to danger), adaptation (how do they compete for food and space to survive) and movement (how do they move).