2.5-

Question 1

The structure of cell membranes results in

Answer 1

Selective permeability

Question 2

Cell membranes separate the

Answer 2

internal environment of the cell from the external environment.

Question 3

Selective permeability is a direct consequence of

Answer 3

membrane structure, as described by the fluid mosaic model.

Question 4

Small nonpolar molecules,

Answer 4

N2, O2, and CO2 , freely pass across the membrane.

Question 5

Hydrophilic substances, such as large polar molecules and ions, move across the membrane through

Answer 5

embedded channel and transport proteins.

Question 6

Polar uncharged molecules, including H2O,

Answer 6

Pass through the membrane in small amounts.

Question 7

Cell walls provide a

Answer 7

structural boundary, as well as a permeability barrier for some substances to the internal environments.

Question 8

Cell walls of plants, prokaryotes, and fungi

Answer 8

are composed of complex carbohydrates.