Question

Which substance can enter a cell by diffusion

Answer 1

(1) water because the others are just too complex to be diffused without being digested but water can be diffused as is.

Answer 2

Answer;
The substance that can enter a cell by diffusion without having to be digested is water.

Explanation;
Diffusion involves the movement of molecules from a region of high concentration to a region of low concentration, down a concentration gradient.
Water is able to diffuse through the cell membrane without being digested since it has small molecules.
One property of cell membrane is semi-permeability; it selectively allows material to enter or leave the cell. Large molecules such as starch , fat and proteins, can not enter the cell due to their size and will need to be digested to small molecules for the to gain access to the cell.