CH 5: Cell Membranes

1. CH 5: Cell Membranes Practice Test answers

2. The movement of a substance toward an area of lower concentration is called ________. • diffusion • osmosis • active transport • exocytosis

3. Which component in the cell membrane restricts the passage of water-soluble substances? • glycolipids • protein • oligosaccharides • phospholipid

4. A membrane protein with two hydrophilic domains will generally: • be an enzyme • be an integral membrane protein • be a peripheral membrane protein • be involved with cell recognition

5. Which type of membrane protein will bind to a signal molecule such as a hormone? • adhesion • passive transporter • cell-to-cell communication • receptor

6. Communication proteins permit ________. • a cell to respond to extracellular signals • cells to import signal molecules from the extracellular environment • signaling between adjacent cells • body cells to distinguish foreign cells

7. Which combination of conditions would promote the most rapid diffusion across a cell membrane? • large molecule, high temperature, large concentration gradient • large molecule, low temperature, small concentration gradient • small molecule, low temperature, small concentration gradient • small molecule, high temperature, large concentration gradient

8. The term "selective permeability" describes the characteristic of membranes that ________. • restrict the passage of polar molecules • provide an anchoring between adjacent cells • allow membrane proteins to float freely within the membrane • permit some molecules to cross the membrane while preventing others from crossing

9. In the absence of a specific carrier protein, which type of molecule would be least likely to cross the membrane? • one that is large and polar • one that is small and nonpolar • one that is large and nonpolar • one that is small and polar

10. Why is diffusion the method by which O2 and CO2 are transported across the cell membrane? • it is faster than active transport • it allows ions and molecules to accumulate at higher concentrations within the cell than in the surrounding environment • the phospholipid bilayer is permeable to small, non-polar molecules • protein components are needed in the cell membrane for diffusion to occur

11. Nerve cells contain an unusually high concentration of potassium; how are they able to obtain concentrations of potassium greater than those of the surrounding extracellular environment? • reverse diffusion • reverse osmosis • active transport • facilitated diffusion

12. Which of the following is a characteristic of active transport? • solute movement across the membrane is toward the side with the higher concentration • specific membrane proteins are required but no energy is needed • only molecules with potential energy greater than ATP are transported • it is a passive process

13. Proteins in membranes can provide all of the following functions except ________. • carriers for polar molecules • insulation • receptors • enzymes

14. Imagine cells suspended in a fluid to which a large amount of salt is suddenly added. If the cell membrane were impermeable to the salt, the cell would subsequently ________. • die • swell as it gains water osmotically • shrink as it loses water osmotically • experience no changes; since it's impermeable, salt has no effect

15. Osmosis can be described as ________. • movement of water from a region of high solute concentration to a region of low solute concentration • movement of solute from an area of low solute concentration to an area of high solute concentration • water molecules colliding with one another and the wall of a container • movement of water across a membrane from an area of low solute concentration to an area of high solute concentration

16. 2. 3. 1. B C A Which graphic, A, B, or C, portrays what would happen to cells in a hypertonic environment? • A • B • C

17. The cell membrane ________. • is selectively permeable • has a bilayered phospholipid-protein structure • defines the boundary of the cell • all of the choices

18. The most abundant lipid in a cell membrane is ________. • phospholipid • steroids • cholesterol • triglycerides

19. When a plant cell is placed in a hypotonic solution the plant cell will • Lose water from its vacuole. • Not be affected • Take in water and potentially burst • Take in water and expand up to its cell wall.

20. What feature of a vesicle would indicate an endocytotic formation? • there would not be any receptor proteins • it would contain cytoplasmic fluid • it would contain extracellular fluid • integral proteins would be absent

21. Phagocytosis is one type of ________. • active transport • osmosis • exocytosis • endocytosis