Which statement describes the currently accepted theory of how an enzyme and its substrate fit together?
A. As the product is released, the enzyme breaks down.
B. The enzyme is like a key that fits into the substrate, which is like a lock.
C. The active site is permanently changed by its interaction with the substrate.
D. As the substrate binds to the enzyme, the shape of the active site changes to accommodate the reaction.
Which of the following is consistent with the laws of physics governing energy?
A. When a liter of gasoline is burned in a car engine, 100% of its energy goes into moving the car along the road.
B. You eat a "quarter-pounder" hamburger and assemble exactly a quarter-pound of additional body weight on your body.
C. Eventually sunlight that is absorbed on the earth returns to space as dispersed heat.
D. A calorie of sunlight becomes a calorie of plant tissue that, eaten by you, becomes a calorie of heat lost in muscle "power."
E. Chemical bonds are a case of converting energy to matter; breaking the bonds converts matter to energy.
What establishes the electrochemical gradient across a membrane to provide energy for ATP production?
A. The chloroplast's electron transport system provides the ions.
B. Hydrogen ions naturally collect on the outside of the organelle membrane.
C. Hydrogen ions are pumped across the membrane by carrier proteins of the electron transport chain.
D. All of the choices establish the electrochemical gradient.
An automobile engine is about 20 - 30% efficient in converting chemical energy to mechanical energy. Cells are about 39% efficient if the transformation of glucose to ATP. The rest of the energy is lost as heat. This is illustrative of the:
A. First Law of Thermodynamics.
B. Second Law of Thermodynamics.
C. Third Law of Thermodynamics.
D. The Cell Theory.
While eating a container of yogurt, you have to leave, so you store the yogurt in the refrigerator. A day later you return and find the surface of the yogurt is no longer smooth but has broken into several liquified products. You correctly guess that enzymes from your saliva, via the spoon, have continued digesting the yogurt in your absence. What will happen over time?
A. The reaction will soon stop because the amount of saliva is small, and you would have to add more saliva to continue the degradation.
B. The reaction will continue, since the enzyme is not consumed by the reaction.
C. The reaction will continue until half is digested and then stop because the reaction between substrate and product will be balanced.
D. Absolutely no degradation of the yogurt will occur naturally unless in the presence of this enzyme.
aB. The reaction will continue, since the enzyme is not consumed by the reaction.
bD. As the substrate binds to the enzyme, the shape of the active site changes to accommodate the reaction.
cC. Eventually sunlight that is absorbed on the earth returns to space as dispersed heat.
dC. Hydrogen ions are pumped across the membrane by carrier proteins of the electron transport chain.
eB. Second Law of Thermodynamics.
5 Multiple Choice Questions
D. An enzyme's activity is generally reduced by an increase in substrate concentration.
B. Reactions that occur spontaneously are those that increase the amount of useful energy in a system.
D. All of the choices are correct.
5 True/False Questions
A living organism represents stored energy in the form of chemical compounds. When an organism dies, what happens to this stored energy?
A. All chemicals immediately lose their high-energy bonds.
B. All molecules immediately degrade into basic elements.
C. All energy immediately leaves, and that is one manifestation that the organism is dead.
D. The chemical compounds in cells lose their organization over time because there is no longer an input of energy to maintain the organized state.
E. The chemical compounds remain exactly intact and ready to start up again unless digested by a consumer or decay organism. → False
__________ represents the first reactant of this metabolic pathway and ________ reperesents the endproduct (s) of the pathway?
A. A; E
B. B; E and F
C. A; E and F
D. A and B; D and E → B.http://www.flickr.com/photos/60296733@N06/5514033968/
In the electron transport systems of chloroplasts and mitrochondria,
A. the system consists of a series of membrane bound carriers that transfer electrons from one carrier to another.
B. high energy electrons enter the system and low energy electrons exit the system.
C. energy release occurs when the electron transfers from one carrier to another.
D. All of the choices are correct. → D. addition of distilled water
ATP is considered to be
A. an enzyme used widely in all kinds of cells.
B. a coenzyme used to inhibit or activate different enzymes.
C. a molecule that carries a great deal of chemical energy in a chemical bond.
D. the precursor of a high-energy membrane-bounded protein. → C. a molecule that carries a great deal of chemical energy in a chemical bond.
In this pathway, B C is coupled with ADP ATP. Categorize the reactions as endergonic or exergonic.
A. B C is endergonic and ADP ATP is exergonic.
B. ADP ATP is endergonic and B C is exergonic.
C. Both B C and ADP ATP are endergonic.
D. Both B C and ADP ATP are exergonic. → B. ADP ATP is endergonic and B C is exergonic.