Q: Answer the following question given this paragraph: If a cell were a house, the plasma membrane would be walls with windows and doors. Moving things in and out of the cell is an important role of the plasma membrane. It controls everything that enters and leaves the cell. There are two basic ways that substances can cross the plasma membrane: passive transport and active transport. Q: In how many basic was can substances cross the plasma membrane? A:

Choices: i. one. ii. three. iii. four. iv. two.
The answer is:
iv.