Here's why:

* Cytoplasm is the gel-like substance that fills the inside of a cell. It's where many of the cell's important processes take place, like metabolism and the movement of organelles.

* All living cells, whether they are plant or animal, need cytoplasm to function properly.

So, while plant and animal cells have different structures like cell walls (plants) and lysosomes (animals), they both share the essential component of cytoplasm.