Biology 5.10-5.16

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

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

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

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 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

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

B

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

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

Americans spend up to $100 billion annually for bottled water (41 billion gallons). The only beverages with higher sales are carbonated soft drinks. Recent news stories have highlighted the fact that most bottled water comes from municipal water supplies (the same source as your tap water), although it may undergo an extra purification step called reverse osmosis. Imagine two tanks that are separated by a membrane that's permeable to water, but not to the dissolved minerals present in the water. Tank A contains tap water and Tank B contains the purified water. Under normal conditions, the purified water would cross the membrane to dilute the more concentrated tap water solution. In the reverse osmosis process, pressure is applied to the tap water tank to force the water molecules across the membrane into the pure water tank. 1) After the reverse osmosis system has been operating for 30 minutes, the solution in Tank A would A) be hypotonic to Tank B. B) be isotonic to Tank B. C) be hypertonic to Tank B. D) contain more minerals than Tank B. E) move by passive transport to Tank B.

C

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) competitive inhibition. B) noncompetitive inhibition. C) feedback inhibition. D) positive feedback. E) irreversible inhibition.

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

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

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. 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. E) 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

How does inhibition of an enzyme-catalyzed reaction by a competitive inhibitor differ from inhibition by a noncompetitive inhibitor? A) Competitive inhibitors interfere with the enzyme; noncompetitive inhibitors interfere with the reactants. B) Competitive inhibitors bind to the enzyme reversibly; noncompetitive inhibitors bind to it irreversibly. C) Competitive inhibitors change the enzyme's tertiary structure; noncompetitive inhibitors cause polypeptide subunits to dissociate. D) Competitive inhibitors bind to the active site of the enzyme; noncompetitive inhibitors bind to a different site. E) Competitive inhibitors are inorganic substances such as metal ions; noncompetitive inhibitors are vitamins or vitamin derivatives.

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

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 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

2) If you shut the system off and pressure was no longer applied to Tank A, you would expect A) the water movement to follow the concentration gradient. B) the water to reverse flow from B to A. C) the water to flow in equal amounts in both directions. D) the water to flow against the concentration gradient. E) both a and b above to occur.

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

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 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