Question

Why is cytoplasmic streaming called "active mass movement of cytoplasm"? ...?

Answer 1

Hi , cytoplasmic streaming is actually circulating around in the cell . It moves and by doing do it can help move organelles and harmful/helpful chemicals to where they need to be in the cell , so that's why cytoplasmic streaming is also called active mass movement of cytoplasm.
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Answer 2

Because the cytoplasm is actually circulating around in the cell. It's not just a "gel-like" substance that sits statically. It moves and by doing so it can help move organelles and and helpful/harmful chemicals to where they need to be in the cell.