What is free energy?a. the energy available to do useful work in a given system
What is free energy?a. the energy available to do useful work in a given system
b. the minimum amount of energy needed to break a particular type of bond
c. the energy needed to begin a chemical reaction
d. the energy stored in a substance, either through its position or composition
What type chemical reaction releases free energy?
a. an isothermic reaction
b. an exergonic reaction
c. an endothermic reaction
d. an endergonic reaction
____ 5. What is the name of the temporary condition in which bonds in a reactant begin to break and new bonds begin
to form?
a. activation point
b. transition state
c. “excited” state
d. breaking point
____ 6. What is an endothermic reaction?
a. absorbs free energy, so the products have more free energy than the reactants.
b. releases energy, so the products have less potential energy than the reactants.
c. absorbs energy, so the products have more potential energy than the reactants.
d. releases free energy, so the products have less free energy than the reactants.
Which of these molecules is most directly involved in energy transfer in cells?
a. CO 2
b. O 2
c. ATP
d. H 2 O
The contraction of muscle fibres is an example of which type of work carried out by ATP?
a. transport
b. chemical
c. mechanical
d. all of the above
____ 10. What are the products of the ATP hydrolysis reaction?
a. adenosine diphosphate, water, and free energy
b. adenine, an inorganic phosphate, and free energy
c. adenine, three equally bonded phosphates, and free energy
d. adenosine diphosphate, an inorganic phosphate, and free energy
____ 11. In the body, which process converts the chemical energy in glucose to the chemical energy in ATP?
a. cellular respiration
b. anabolism
c. ATP hydrolysis
d. digestion
he contraction of muscle fibres is an example of which type of work carried out by ATP?
a. transport
b. chemical
c. mechanical
d. all of the above
____ 10. What are the products of the ATP hydrolysis reaction?
a. adenosine diphosphate, water, and free energy
b. adenine, an inorganic phosphate, and free energy
c. adenine, three equally bonded phosphates, and free energy
d. adenosine diphosphate, an inorganic phosphate, and free energy
____ 11. In the body, which process converts the chemical energy in glucose to the chemical energy in ATP?
a. cellular respiration
b. anabolism
c. ATP hydrolysis
d. digestion
____ 12. What is true of enzymes?
a. Enzymes function best at a particular pH.
b. Some enzymes need activators or cofactors.
c. Enzymes function best at specific temperatures but break down at high temperatures.
d. All of the above.
____ 13. Enzymes function as catalysts by
a. decreasing the activation energy of the reaction.
b. increasing the activation energy of the reaction.
c. decreasing the free energy of the reactants.
d. increasing the free energy of the reactants.
____ 14. What is true of NADH?
a. It oxidizes to release protons and electrons.
b. It is a carrier of both protons and electrons.
c. It is the reduced form of the coenzyme NAD + .
d. All of the above.
____ 15. What happens when oxygen gas changes to form water?
a. Anabolic reactions occur and oxygen is oxidized.
b. Catabolic reactions occur and oxygen is reduced.
c. Anabolic reactions occur and oxygen is reduced.
d. Catabolic reactions occur and oxygen is oxidized.
Section B: Modified True/False
Indicate whether the statement is true or false. If false, change the BOLDED word(s) or phrase to make the statement true.
____ 1. Activation energy is the minimum amount of energy needed to start a chemical reaction.____________________
____ 2. The Second Law of Thermodynamics states that energy can change forms, but is not created nor destroyed.____________________
____ 3. Spontaneous change is a change that continues on its own once it has started. ____________________
____ 4. Free energy is the minimum amount of energy needed to break a particular type of bond, while activation energy is energy that can do useful work. __________________ __________________
____ 5. The production of a large molecule from smaller subunits is called a catabolic reaction.
____________________
____ 6. An exergonic reaction absorbs free energy, so the products have more energy than the reactants.________________ ______________
____ 7. Phosphorylation involves the transfer of a phosphate group to an organic molecule and causes the molecule to become less reactive. ____________________
____ 8. The ATP molecule consists of a deoxyribose sugar, the nucleic acid adenine, and three unequally bonded phosphates. ____________________
____ 9. An enzyme functions by changing the shape, the charge, or the distance between substrates. ____________________
____ 10. Enzymes work as catalysts by decreasing the free energy of the reactants. ____________________
Completion Complete each statement. Fill in the blank.
1. ____________________ energy is stored in an object, and is dependent on the object’s ________________ or composition.
2. Redox reactions involve the transfer of one or more electrons from one molecule to another. When an atom or molecule loses electrons, the process is called _________________________ and when an atom or molecule gains electrons, the process is called ____________________.
3. The _________________________ Law of Thermodynamics states that, in every energy transfer or conversion, some of the useful energy becomes unusable and is released as ________________ energy.
4. Dehydrogenase is an enzyme that oxidizes a food substrate and transfers _______________ ions to a(n) electron _________________ atom.
5. Cellular respiration is an example of a(n) ________________ pathway.
6. The net energy changes that occur in rapid combustion and controlled oxidation of glucose are __________.
Match each term with the most appropriate description. Each answer may be used ONLY ONCE.
a. Energy e. free energy
b. Metabolism f. potential energy
c. bond energy g. activation energy
d. transition state h. entropy
____ 1. condition in which bonds are breaking within reactants and forming between products
____ 2. ability to do work
____ 3. sum of all anabolic and catabolic processes in a cell or organism
____ 4. amount of energy required to break apart a mole of molecules into its constituent atoms
____ 5. measure of disorder in a system
Match each term with the most appropriate description. Each answer may be used MORE THAN ONCE.
a. active site d. induced fit model
b. enzymes e. substrate
c. enzyme-substrate complex f. ΔG
____ 6. enzyme changes shape to better accommodate the substrate
____ 7. the location where substrate binds to an enzyme
____ 8. unaffected by an enzyme
____ 9. change in free energy during a reaction
____ 10. an enzyme with its substrate attached to the active site
Short Answer
1. For each process, state:
i) whether it is exothermic or endothermic
ii) whether it results in an increase in entropy or a decrease in entropy
iii) whether it is spontaneous or non-spontaneous
a) lighting fireworks
b) the melting of wax
c) bicycling up a hill
d) a growing muscle
Draw a diagram for an ATP molecule. Make sure to label all the parts.
Next, describe how ATP is important for humans by describing all the types of work that ATP does in the cells. Finally, describe who ATP hydrolysis works and how this reaction can power many types of reactions in the cell. What is this process called in general?
2. What are the three mechanisms by which enzymes can lower the activation energy for a reaction? Draw each method and explain how each method can reduce the amount of energy required to break or make chemical bonds.
3. Explain why electrons in C-H bonds are a good source of energy. Draw a diagram comparing this to an O-H bond and explaining why this type of bond will have less energy. Using these examples, rank carbohydrates, fats, and proteins based on energy content, explaining which have more or less energy and why.