5 Written questions
5 Matching questions
- In order to roll a rock down a hillside, you must first push it up out of the hole in which it rests. Pushing the rock is analogous to the energy of activation of a chemical reaction.
- If there are twelve different intermediate products produced in the stages for production of a molecule in a cell, we can expect that there
A. is one enzyme that carries this process through to the end product.
B. is one enzyme for degradation and another enzyme for synthesis.
C. may not be any enzymes involved if this is a natural cell product.
D. must be twelve different raw materials combined in the cell by one enzyme.
E. are about twelve enzymes, at least one responsible for each step in the metabolic pathway.
- Coupling occurs when the energy released by an exergonic reaction is:
A. used to drive another exergonic reaction.
B. used to drive an endergonic reaction.
C. lost as nonusable heat to the environment.
D. used to decrease the entropy of the universe.
E. All of the choices are correct.
- 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.
- 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.
- a E. are about twelve enzymes, at least one responsible for each step in the metabolic pathway.
- b True
- c B. used to drive an endergonic reaction.
- d B. The reaction will continue, since the enzyme is not consumed by the reaction.
- e D. As the substrate binds to the enzyme, the shape of the active site changes to accommodate the reaction.
5 Multiple choice questions
- C. A; E and F
- 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.
- D. oxidized; reduced
5 True/False questions
The activity of an enzyme might be increased by all of the following except ________?
A. increase in substrate concentration.
B. a vitamin.
C. 2-4 degree increase in temperature.
D. lead. → B. Reactions that occur spontaneously are those that increase the amount of useful energy in a system.
Which best describes the second law of thermodynamics?
A. Energy is not created nor destroyed, but it can change into matter.
B. Energy is not created nor destroyed, but it can change from one energy form to another.
C. Energy can be created from matter or used to produce matter.
D. Some useful energy is lost as heat whenever an energy transfer occurs.
E. Energy transfers are always 100% efficient in changing energy from one useful form to another. → D. Some useful energy is lost as heat whenever an energy transfer occurs.
Of the following, which process will not denature a protein?
A. heating to temperatures above 100 C
B. addition of strong acids or strong bases
D. addition of distilled water → C. a muscle contracting
ATP is considered a high-energy compound because under cellular conditions, 7.3 kcal per mole of energy is released when a bond is broken between:
A. the base adenine and the sugar ribose.
B. the adenosine and the phosphate groups.
C. the base adenine and the phosphate groups.
D. the adenosine diphosphate and the third phosphate.
E. All of the bonds release energy as ATP is completely broken down. → C. a molecule that carries a great deal of chemical energy in a chemical bond.
If the reaction graphed at right is coupled with D→E, then D →E is:
D. none of the above → B. endergonic