Chp5 Questions

33) Aquaporins A) allow water to cross the plasma membrane via facilitated diffusion. B) allow water to cross the plasma membrane against its concentration gradient. C) allow for the active transport of water. D) are found in all cells.

A) allow water to cross the plasma membrane via facilitated diffusion.

42) Glucose molecules provide energy to power the swimming motion of sperm. In this example, the sperm are changing A) chemical energy into kinetic energy. B) chemical energy into potential energy. C) kinetic energy into potential energy. D) kinetic energy into thermal energy.

A) chemical energy into kinetic energy.

14) Small, nonpolar, hydrophobic molecules such as fatty acids A) easily pass through a membrane's lipid bilayer. B) very slowly diffuse through a membrane's lipid bilayer. C) require transport proteins to pass through a membrane's lipid bilayer. D) are actively transported across cell membranes.

A) easily pass through a membrane's lipid bilayer.

23) A cell that has neither a net gain of water nor net loss of water when it is immersed in a solution must be A) isotonic to its environment. B) hypertonic to its environment. C) hypotonic to its environment. D) metabolically inactive.

A) isotonic to its environment.

19) Osmosis can be defined as A) the diffusion of water. B) the diffusion of nonpolar molecules. C) active transport. D) the diffusion of a solute.

A) the diffusion of water.

18) Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of A) exocytosis. B) passive transport. C) active transport. D) endocytosis.

B) passive transport.

59) Most of a cell's enzymes are A) lipids. B) proteins. C) amino acids. D) carbohydrates.

B) proteins.

Most of the functions of a cell membrane, including transport and enzymatic function, are performed by A) glycolipids. B) proteins. C) phospholipids. D) cholesterol.

B) proteins.

10) Plasma membranes are selectively permeable. This means that A) anything can pass into or out of a cell as long as the membrane is intact and the cell is healthy. B) the plasma membrane allows some substances to enter or leave a cell more easily than others. C) glucose cannot enter the cell. D) plasma membranes must be very thick.

B) the plasma membrane allows some substances to enter or leave a cell more easily than others.

15) Which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer? A) O2 B) CO2 C) Na+ D) a small, nonpolar molecule such as butane (C4H10)

C) Na+

Membrane phospholipids A) have hydrophobic heads that face the center of the membrane and are shielded from water. B) have hydrophilic tails that face outward and are exposed to water. C) are able to drift about in the plasma membrane. D) remain fluid because they are tightly packed against one another.

C) are able to drift about in the plasma membrane.

54) The transfer of a phosphate group to a molecule or compound is called A) carboxylation. B) ionization. C) phosphorylation. D) hydrogenation.

C) phosphorylation

57) An energy barrier A) is the amount of energy that must be produced by the reactants to end a chemical reaction. B) is higher than the activation energy of a reaction. C) prevents the spontaneous breakdown of molecules in the cell. D) can only be overcome with the use of enzymes.

C) prevents the spontaneous breakdown of molecules in the cell.

53) Which of the following statements about the ATP molecule is true? A) It contains five phosphate groups. B) Extremely stable bonds link the second and third phosphate groups. C) It contains the sugar glucose. D) It releases energy when one phosphate group leaves ATP.

D) It releases energy when one phosphate group leaves ATP.

58) The energy required to initiate an exergonic reaction is called A) exergonic energy. B) endergonic energy. C) input energy. D) activation energy.

D) activation energy.

61) Substrates bind to an enzyme's ________ site. A) allosteric B) inhibitory C) phosphate D) active

D) active

34) Which of the following processes can move a solute against its concentration gradient? A) osmosis B) passive transport C) facilitated diffusion D) active transport

D) active transport

The fluid mosaic model describes the plasma membrane as consisting of A) a phospholipid bilayer with embedded carbohydrates. B) two layers of phospholipids with cholesterol sandwiched between them. C) carbohydrates and phospholipids that can drift in the membrane. D) diverse proteins embedded in a phospholipid bilayer.

D) diverse proteins embedded in a phospholipid bilayer.

47) Which of the following direct energy transfers is impossible in living systems? A) light energy to chemical energy B) chemical energy to kinetic energy C) light energy to potential energy D) heat to light energy

D) heat to light energy

16) Oxygen crosses a plasma membrane by A) osmosis. B) active transport. C) pinocytosis. D) passive transport.

D) passive transport

31) The molecules responsible for membrane transport are A) steroids. B) phospholipids. C) carbohydrates. D) proteins.

D) proteins.

25) If placed in tap water, an animal cell will undergo lysis, whereas a plant cell will not. What accounts for this difference? A) the expulsion of water by the plant cell's central vacuole B) the relative impermeability of the plant cell wall to water C) the fact that plant cells are isotonic to tap water D) the relative inelasticity and strength of the plant cell wall

D) the relative inelasticity and strength of the plant cell wall