Explain why large, multicellular organisms must have trillions of microscopic cells rather than thousands of larger cells.

There are trillions of cells EVERYWHERE including blood cells, brain cells, and even skin cells !! I believe that multicellular organisms that are large need to have trillions of cells to be able to fill their whole body. For example , humans, Humans have one of the most complex cells, we humans are very big so thousands of cells would not be enough to contain our entire body. Even the word ' multicellular' meaning multiple cells gives people a hint that we are multicellular . In conclusion , trillions of cells are needed for multicellular organisms , without them we wouldn't be able to function properly.

That is true tge cactus as a structural adaptation to its envirinment has it leaves reduced to spines. but this doesnt mean it cant produce food it produces food because of the presence of chlorophyll in its stem