Mastering Bio Chapter 5

A cell that neither gains nor loses water when it is immersed in a solution is A) isotonic to its environment. B) hypertonic to its environment. C) hypotonic to its environment. D) metabolically inactive. E) dead.

A

A child is brought to the hospital with a fever of 107°F. Doctors immediately order an ice bath to lower the child's temperature. Which of the following statements offers the most logical explanation for this action? A) Elevated body temperature will increase reaction rates in the child's cells and overload the limited number of enzymes found in the cell. B) Elevated body temperatures may denature enzymes. This would interfere with the cell's abilities to catalyze various reactions. C) Elevated body temperatures will increase the energy of activation needed to start various chemical reactions in the body. This will interfere with the ability of enzymes to catalyze vital chemical reactions. D) Elevated body temperatures cause molecules to vibrate more quickly and prevent enzymes from easily attaching to reactants. This would slow vital body reactions. E) Elevated body temperatures easily break the covalent bonds linking biologically important molecules. This will cause a general breakdown of cell structures.

B

A major function of glycoproteins and glycolipids in the cell membrane is to A) glue cells together to form tissues. B) allow the cells of an embryo to sort themselves into tissues and organs. C) attach the cell membrane to the cytoskeleton. D) help the cell resist swelling. E) help the cell retain its shape.

B

A steer must eat at least 100 pounds of grain to gain less than 10 pounds of muscle tissue. This illustrates A) the first law of thermodynamics. B) the second law of thermodynamics. C) that some energy is destroyed in every energy conversion. D) that energy transformations are typically 100% efficient. E) that thermal energy can be transformed into chemical energy.

B

According to ________, energy cannot be created or destroyed. A) Aristotle's first principle B) the first law of thermodynamics C) the second law of thermodynamics D) the third law of thermodynamics E) Einstein's law of relativity

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) diffusion D) pinocytosis E) passive transport

B

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

E

Which of the following is a coenzyme? A) zinc B) vitamin B6 C) iron D) iodine E) hydrogen ions

B

The process of a white blood cell engulfing a bacterium is A) osmosis. B) diffusion. 10 C) receptor-mediated endocytosis. D) pinocytosis. E) phagocytosis.

E

A plant cell in a hypotonic solution A) is turgid. B) lyses. C) shrivels. D) wilts. E) is flaccid.

A

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

A

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 chemical energy. E) kinetic energy into thermal energy.

A

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

A

In the lab, you use a special balloon that is permeable to water, but not sucrose, to make an "artificial cell." The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water. Which of the following will occur? A) Water will leave the balloon. B) Water will enter the balloon. C) Sucrose will leave the balloon. 6 D) Sucrose will enter the balloon. E) Sucrose and water will pass across the balloon simultaneously.

A

Many of the enzymes that control a deep-sea firefly squid's ability to produce light energy from chemical energy are located A) in membranes. B) in the nucleus. C) within chloroplasts. D) outside of cells. E) within mitochondria.

A

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. E) endocytosis.

A

Relaying a message from a membrane receptor to a molecule that performs a specific function within a cell is called A) signal transduction. B) inhibition. C) competition. D) self-recognition. E) selective permeability.

A

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. E) usually enter the cell via endocytosis.

A

When a cell uses chemical energy to perform work, it couples a(n) ________ reaction with a(n) ________ reaction. A) exergonic . . . endergonic B) endergonic . . . exergonic C) exergonic . . . spontaneous D) spontaneous . . . exergonic E) endergonic . . . spontaneous

A

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

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 water concentration. B) exhibit a net movement to the side with higher water concentration. C) exhibit a net movement to the side with lower solute concentration. D) exhibit an equal movement in both directions across the membrane. E) not cross the membrane.

A

Which of the following examples is classified as a metabolic pathway? A) protein synthesis B) osmosis C) cell lysis D) spontaneous combustions E) passive diffusion

A

Which of the following processes could result in the net movement of a substance into a cell, if the substance is more concentrated in the cell than in the surroundings? A) active transport B) facilitated diffusion C) diffusion D) osmosis E) passive transport.

A

In the lab, you use a special balloon that is permeable to water but not sucrose to make an "artificial cell." The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water. The solution in the balloon is ________ relative to the solution in the beaker. A) isotonic B) hypotonic C) hypertonic D) hydrophobic E) hydrophilic

B

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

B

Most of the functions of a cell membrane are performed by A) glycolipids. B) proteins. C) phospholipids. D) cholesterol. E) nucleotides.

B

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

B

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) cholesterol cannot enter the cell. E) plasma membranes must be very thick.

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) is hypotonic to the protozoan. C) is contaminated with pollutants. D) contains a higher concentration of solutes than the protozoan. E) is hypertonic to the protozoan.

B

The cholesterol associated with animal cell membranes A) is attached to membrane proteins and extends into the watery environment surrounding the cell. B) helps to stabilize the cell membrane at body temperature. C) makes the cell membrane fluid at room temperature.D) is an abnormality resulting from a diet high in cholesterol. E) helps solidify the membranes when the room temperature is below freezing.

B

Which characteristic promoted the utilization of lipids as the first cell membrane? A) spontaneous degradation of the intracellular environment B) self-assembly into a simple membrane C) ability to form an impermeable membrane D) formation of a semi-solid membrane E) utilization of the hydrophilic nature of lipids

B

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

B

ATP can be used as the cell's energy exchange mechanism because A) endergonic reactions can be fueled by coupling them with the formation of ATP from ADP. B) ATP is the most energy-rich small molecule in the cell. C) endergonic reactions can be fueled by coupling them with the hydrolysis of high-energy phosphate bonds in ATP. D) the regeneration of ATP from ADP can be fueled by coupling it with endergonic reactions. E) ATP is a disposable form of chemical energy, used once and then discarded by the cell.

C

Cells acquire LDLs by A) osmosis. B) diffusion. C) receptor-mediated endocytosis. D) pinocytosis. E) phagocytosis.

C

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

C

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

C

Living systems A) violate the first law of thermodynamics. B) violate the second law of thermodynamics. C) decrease their entropy while increasing the entropy of the universe. D) are examples of a closed system. E) are only compelled to follow the first law of thermodynamics.

C

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) often have "kinks" in their tails caused by the presence of a double bond between carbons. D) remain fluid because they are tightly packed against one another. E) form impermeable layers for cells .

C

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

C

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

C

When physicians perform an organ transplant, they choose a donor whose tissues match those of the recipient as closely as possible. Which of the following cell components are being matched? A) plasma membrane phospholipids B) plasma membrane proteins C) cell-surface carbohydrates D) plasma membrane cholesterols E) cytoskeletal elements

C

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

C

Which of the following statements concerning energy is false? A) Fireflies are able to take potential energy in the form of food and convert that energy into kinetic energy in the form of heat and light. B) A gasoline engine converts chemical energy into kinetic energy.13 C) Living systems convert heat energy into chemical energy to reduce entropy. D) Energy transformations in cells are accompanied by the release of heat energy. E) During photosynthesis, plants convert kinetic energy into chemical energy.

C

Which of the following statements regarding enzyme function is false? A) An enzyme's function depends on its three-dimensional shape. B) Enzymes are very specific for certain substrates. C) Enzymes are used up in chemical reactions. D) Enzymes emerge unchanged from the reactions they catalyze.An enzyme binds to its substrate at the enzyme's active site

C

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

C

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

D

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

D

In the reaction A → B + C + heat, A) there is a net input of energy. B) the potential energy of the products is greater than that of the reactant. C) the potential energy of the products is the same as that of the reactant. D) the potential energy of the products is less than that of the reactant. E) entropy has decreased.

D

Inhibition of an enzyme is irreversible when A) a competitive inhibitor is involved. B) a noncompetitive inhibitor is involved. C) the shape of the enzyme is changed. D) covalent bonds form between inhibitor and enzyme. E) weak interactions form between inhibitor and enzyme.

D

Kinetic energy differs from chemical energy in that A) kinetic energy is stored energy that has the potential to do work, and chemical energy is the energy of movement. B) kinetic energy depends on the movement of atoms, whereas chemical energy depends on the movement of molecules. C) kinetic energy can be converted into various forms of energy, whereas chemical energy can only be converted into heat. D) kinetic energy is the energy of a moving object, whereas chemical energy is the potential energy of molecules. E) chemical energy is a particular form of kinetic energy.

D

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

E

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

D

Which of the following statements about the ATP molecule is true? A) It contains two phosphate groups. B) Extremely stable bonds link the second and third phosphate groups. C) It contains the six-carbon sugar hexose. D) It contains a nitrogenous base molecule called adenine. E) It can be coupled with an exergonic reaction.

D

Which of the following statements regarding active transport is false? A) Active transport uses ATP as an energy source. B) Active transport can move solutes up a concentration gradient. C) Active transport requires the cell to expend energy. D) Active transport is driven by the concentration gradient. E) Active transport is necessary to allow nerves to function properly.

D

Which of the following statements regarding diffusion is false? A) Diffusion is a result of the kinetic energy of atoms and molecules. B) Diffusion is driven by concentration gradients C) Diffusion requires no input of energy into the system. D) Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated. E) Diffusion occurs even after equilibrium is reached and no net change is apparent.

D

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

D

Which of the following statements regarding membrane function is false? A) The plasma membrane forms a selective barrier around the cell. B) The plasma membrane plays a role in signal transduction. C) The plasma membrane has receptors for chemical messages. D) The plasma membrane is the control center of the cell. E) The plasma membrane is involved in self-recognition

D

Which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer? A) H2O B) O2 C) CO2 D) Na+ E) a small, nonpolar molecule such as butane (C4H10)

D

White blood cells (WBCs) are more resistant to lysis than red blood cells (RBCs). When looking at a sample of blood for WBCs, would could you do to reduce interference from RBCs? A) Mix the blood in a salty solution to cause the RBCs to lyse. B) Mix the blood in an isotonic solution and allow the WBCs to float to the top. C) Mix the blood with a dye that stains the proteins in the cytoplasm. D) Mix the blood in a hypotonic solution, which will cause the RBCs to lyse. E) Mix the blood in a hypertonic solution, which will cause the RBCs to lyse.

D

You are adrift in the Atlantic Ocean, and, being thirsty, drink the surrounding seawater. As a result, A) you quench your thirst. B) your cells lyse, due to the excessive intake of salt. C) your cells become turgid. D) you dehydrate yourself. E) your cells lyse from excessive water intake.

D

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

E

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 membrane to water C) the relative impermeability of the plant cell wall to water D) the fact that plant cells are isotonic to tap water E) the relative inelasticity and strength of the plant cell wall

E

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

E

Substrates bind to an enzyme's ________ site. A) reactant B) allosteric C) regulatory D) phosphate E) active

E

The energy required to initiate an exergonic reaction is called A) exergonic energy. B) endergonic energy. C) input energy. D) hydrolytic energy. E) the energy of activation.

E

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

E

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

E

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

E

Which of the following statements regarding membrane protein function is false? A) Membrane proteins serve as enzymes. B) Membrane proteins act as receptors to molecules like hormones. C) Membrane proteins provide cellular identification tags. D) Membrane proteins form junctions between cells. E) Membrane proteins transfer genetic information to the cytoplasm.

E

Which of the following statements regarding thermodynamics is false? A) Thermodynamics is the study of energy transformations that occur in a collection of matter. B) The collection of matter under study is called the system. C) A single cell or the planet Earth could be a thermodynamic system. D) An open system exchanges both energy and matter with its surroundings. E) An automobile engine is an example of a closed system.

E

Which of the following will have no effect on the rate of an enzyme-catalyzed reaction? A) temperature B) pH C) competitive inhibitors D) noncompetitive inhibitors E) net change in energy

E