H. Bio. Mastering Ch. 5.1-5.15 Review (Multiple Choice)

A plant cell in a hypotonic solution A. becomes turgid because of an inflow of water. B. shrivels because of an outflow of water. C. bursts because of an inflow of water. D. wilts because of an outflow of water.

A

The active site of an enzyme is A. the region of an enzyme that attaches to a substrate. B. the region of a substrate that is changed by an enzyme. C. the highly changeable portion of an enzyme that adapts to fit the substrates of various reactions. D. the region of a product that detaches from the enzyme.

A

The cholesterol associated with animal cell membranes A. helps to keep phospholipids from being too close to one another. B. is an abnormality resulting from a diet high in cholesterol. C. is attached to membrane proteins and extends into the watery environment surrounding the cell. D. helps solidify the membranes when the room temperature is below freezing.

A

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

A

When two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane and osmosis is allowed to take place, the water will A. exhibit a net movement to the side with lower free water concentration. B. exhibit an equal movement in both directions across the membrane. C. exhibit a net movement to the side with lower solute concentration. D. exhibit a net movement to the side with higher free water concentration.

A

Which figure depicts an animal cell placed in a solution hypotonic to the cell? A. Figure 1 B. Figure 2 C. Figure 3

A

Which of the following is a typical feature of an ATP-driven active transport mechanism? A. The solute moves against the concentration gradient. B. The transport protein is irreversibly phosphorylated as transport takes place. C. The transport protein must cross to the correct side of the membrane before the solute can bind to it. D. The transport protein catalyzes the conversion of ADP to ATP.

A

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

A

Anything that prevents ATP formation will most likely A. have no effect on the cell. B. result in cell death. C. force the cell to rely on ADP for energy. D. force the cell to rely on lipids for energy.

B

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

B

Bacterial production of the enzymes needed for the synthesis of the amino acid tryptophan declines with increasing levels of tryptophan and increases as tryptophan levels decline. This is an example of A. irreversible inhibition. B. feedback inhibition. C. noncompetitive inhibition. D. competitive inhibition.

B

Certain cells that line the stomach synthesize a digestive enzyme and secrete it into the stomach. This enzyme is a protein. Which of the following processes could be responsible for its secretion? A. endocytosis B. exocytosis C. pinocytosis D. diffusion

B

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

B

In a hypotonic solution, an animal cell will A. neither gain nor lose water. B. lyse. C. experience turgor. D. shrivel.

B

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

B

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

B

Cells acquire low-density lipoproteins (LDLs) by A. phagocytosis. B. pinocytosis. C. receptor-mediated endocytosis. D. diffusion.

C

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

C

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

C

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

C

The molecules responsible for membrane transport are A. carbohydrates. B. steroids. C. proteins. d. phospholipids.

C

The process of a white blood cell engulfing a bacterium is A. pinocytosis. B. osmosis. C. phagocytosis. D. receptor-mediated endocytosis.

C

Which of the following statements is true for all types of passive transport? A. Proteins are needed to transport molecules across the membrane. B. Ions never cross the plasma membrane by passive transport. C. The concentration gradient is the driving force. D. Only small polar molecules are able to cross the plasma membrane.

C

Which of the following statements regarding enzymes is true? A. An enzyme's function is unaffected by changes in pH. B. Enzymes are inorganic. C. Enzymes catalyze specific reactions. D. All enzymes depend on protein cofactors to function.

C

All cells are enclosed by a plasma membrane that is similar in ________ and ________. A. permeability; content B. lucidity; texture C. thickness; composition D. structure; function

D

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

D

Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient. A. energy and transport proteins; against B. transport proteins; against C. energy and transport proteins; down D. transport proteins; down

D

How does inhibition of an enzyme-catalyzed reaction by a competitive inhibitor differ from inhibition by a noncompetitive inhibitor? A. Competitive inhibitors change the enzyme's tertiary structure; noncompetitive inhibitors cause polypeptide subunits to dissociate. B. Competitive inhibitors interfere with the enzyme; noncompetitive inhibitors interfere with the reactants. C. Competitive inhibitors bind to the enzyme reversibly; noncompetitive inhibitors bind to it irreversibly. D. Competitive inhibitors bind to the active site of the enzyme; noncompetitive inhibitors bind to a different site.

D

Oxygen crosses a plasma membrane by A. endocytosis. B. active transport. C. osmosis. D. passive transport.

D

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. plasma membranes must be very thick. C. glucose cannot enter the cell. D. the plasma membrane allows some substances to enter or leave a cell more easily than others.

D

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

D

Which of the following substances could be a cofactor? A. a ribosome B. a protein C. a polypeptide D. a zinc atom

D

Which part of the ATP molecule breaks free of the rest when an ATP molecule is used for energy? A. part A B. part B C. part C D. part D

D

Phagocytosis is to eating as pinocytosis is to A. drinking. B. osmosis. C. chewing. D. lysis.

A

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

A

Heating inactivates enzymes by A. changing the enzyme's three-dimensional shape. B. removing phosphate groups from the enzyme. C. breaking the covalent bonds that hold the molecule together. D. causing enzyme molecules to stick together.

A

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. metabolically inactive. B. isotonic to its environment. C. hypotonic to its environment. D. hypertonic to its environment.

B

Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment A. is isotonic to the protozoan. B. contains a higher concentration of solutes than the protozoan. C. is hypertonic to the protozoan. D. is hypotonic to the protozoan.

D

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

D

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

D

What is the basic difference between exergonic and endergonic reactions? A. Exergonic reactions involve the breaking of bonds; endergonic reactions involve the formation of bonds. B. In exergonic reactions, the reactants have less chemical energy than the products; in endergonic reactions, the opposite is true. C. Exergonic reactions involve ionic bonds; endergonic reactions involve covalent bonds. D. Exergonic reactions release energy; endergonic reactions absorb it.

D

When a cell uses chemical energy to perform work, it uses the energy released from a(n) ________ reaction to drive a(n) ________ reaction. A. endergonic; exergonic B. exergonic; spontaneous C. spontaneous; exergonic D. exergonic; endergonic

D

When an enzyme catalyzes a reaction, A. it is used once and discarded. B. it raises the activation energy of the reaction. C. it acts as a reactant. D. it lowers the activation energy of the reaction.

D

Which of the following processes is endergonic? A. the breakdown of glucose B. the burning of wood C. cellular respiration D. the synthesis of glucose from carbon dioxide and water

D