When is facilitated diffusion necessary?
when the molecules are too large.
when the molecules are insoluble.
when the direction of movement is opposite to natural diffusion.
none of the above

When the molecules are too large.

Explanation:

Facilitated diffusion refers to the passive transport of substances down the concentration gradient via specific transport proteins present in the membrane. The large, polar, charged substances and ions cannot pass through the small spaces present between hydrophobic tails of membrane phospholipids. The transport proteins transport these substances in energy independent manner.

im not in connections yet but i might can you some questions. what grade are you in?

i'm guessing this is from edg enuity so the answers would be, from top to bottom,

theodor schwann

matthias schleiden

robert hooke

rudolph virchow

anton van leeuwenhoek