Question

How does diffusion limit the size of an organism? How is this counteracted?

a) Diffusion limits nutrient absorption; this is counteracted by active transport.
b) Diffusion limits cell growth; this is counteracted by osmosis.
c) Diffusion limits waste elimination; this is counteracted by exocytosis.
d) Diffusion limits cell division; this is counteracted by mitosis.

Answer 1

Diffusion limits organism size due to its ineffectiveness over longer distances; specialized transport systems evolved to facilitate larger body sizes in multicellular organisms.

Step-by-step explanation:

Diffusion limits the size of an organism by restricting the exchange of nutrients and wastes through the cell membrane over long distances. As the size of a cell increases, the center of the cell may not receive adequate nutrients nor effectively eliminate wastes due to the slow rate of diffusion over larger distances. To counteract this limitation, multicellular organisms have evolved specialized structures and mechanisms, such as circulatory systems, to facilitate faster transport processes for sustaining larger body sizes. For single-celled organisms, maintaining a small size or having a flattened shape helps to ensure efficient diffusion.