Practice Questions-Cell Theory-Plasma Membrane

Identify cholesterol molecule

• structure a

• structure b

• structure h

• structure i

Plasma membranes are selectively permeable. This means

• anything can pass in and out

• the membrane regulates the passage of the material in and out of the cell

• glucose cannot enter the cell

• cholesterol cannot enter

Which is NOT a function of the membrane?

• it forms a selective barrier

• it has receptor proteins for chemical signals

• it is the control center of the cell

• it plays a role in cell identification

Small, nonpolar, hydrophobic molecules such as fatty acids

• easily pass through the membrane's bilayer

• very slowly diffuse through the bilayer

• require transport proteins

• enter through endocytosis

Membrane phospholipids

• have hydrophobic heads that face the center of the membrane and are protected from water

• have hydrophilic tails that face outward

• remain fluid because they are tightly packed

• have hydrophilic heads that are oriented outwards towards water

When doctors perform organ transplants, they choose a donor tissue match. Which component is being matched?

• membrane phospholipids

• membrane proteins

• membrane carbohydrates

• cholesterol

What kinds of molecules pass through a cell membrane most easily?

• ionic

• small and hydrophobic

• large polar

• large and hydrophobic

Which structure is the hydrophilic polar head of the phospholipid molecule?

• F

• D

• C

• A1

Which structure is the hydrophobic tail of the phospholipid molecule?

• E

• B

• G

• A2

How does cholesterol affect the cell membrane in low temperatures?

• prevents it from becoming too rigid

• makes it more viscous
• denatures it
• makes sure it solidifies