1) high-quality energy input equals high-quality energy output
2) total energy input equals total energy output
3) energy is constantly recycled
4) light energy is released to replace the original input of solar energy
1) one molecule of glucose
2) one molecule of ATP
3) one molecule of H2
4) one molecule of CO2
1) a rock on a mountain ledge
2) a space station orbiting Earth
3) a person sitting on a couch while watching TV
4) the high-energy phosphate bonds of a molecule of ATP
5) an archer with a flexed bow
1) the entropy of the universe is always increasing
2) no chemical reaction is 100% efficient
3) energy cannot be created or destroyed but can be converted from one form to another
4) if you conserve energy you will not be as tired
5) the net amount of disorder is always increasing
5) cellular respiration
2) glucose and water
4) heat and water
5) ATP and water
1) kinetic energy is the energy of a moving object, whereas chemical energy is the potential energy of molecules
2) kinetic energy can be converted into various forms of energy, whereas chemical energy can only be converted into heat
3) chemical energy is a particular form of kinetic energy
4) kinetic energy is stored energy that has the potential to do work, and chemical energy is the energy of movement
1) chemical … kinetic
2) kinetic … chemical
3) chemical … potential
4) potential … kinetic
Light is kinetic energy, and molecules possess chemical energy. Chemical energy refers to the potential energy that can be released during chemical reactions.
1) the first law of thermodynamics
2) that some energy is destroyed in every energy conversion
3) that energy transformations are typically 100% efficient
4) the second law of thermodynamics
1) Exergonic reactions release energy; endergonic reactions absorb it.
2) Exergonic reactions involve the breaking of bonds; endergonic reactions involve the formation of bonds.
3) In exergonic reactions, the reactants have less chemical energy than the products; in endergonic reactions, the opposite is true.
4) Exergonic reactions involve ionic bonds; endergonic reactions involve covalent bonds.
1) exergonic … spontaneous
2) spontaneous … exergonic
3) endergonic … exergonic
4) exergonic … endergonic
3) dehydration decomposition
4) dehydration synthesis
Hydrolysis involves breaking bonds with the addition of water.
5) dehydration synthesis
Energy has been released.
In exergonic reactions the products have less potential energy than the reactants.
4) ATP –> ADP + P
The products of endergonic reactions have more potential energy than the reactants.
2) as spontaneous reactions, endergonic reactions do not need an addition of energy
The hydrolysis of ATP provides the energy needed for an endergonic reaction.
Energy has been acquired from the surroundings.
1) ADP + P –> ATP
5) glucose + glucose –> maltose
The energy released by an exergonic reaction can be used to drive an endergonic reaction.
1) It is used to convert an ATP into an AQP.
2) It is acquired by a reactant in an endergonic reaction.
3) It is broken down into one phosphorus and four oxygen atoms.
4) It is acquired by a reactant in an spontaneous reaction.
5) It is acquired by a reactant in an exergonic reaction.
By acquiring the phosphate group the reactant acquires energy.
1) potential energy … positional energy
2) exergonic … uphill
3) kinetic energy … motion
4) exergonic … spontaneous
5) enzyme … protein
Exergonic reactions release energy.
1) the use of an enzyme to reduce EA
2) relationships between the reactants and products in an exergonic reaction
3) the hydrolysis of ATP to ADP + P
4) The use of energy released from an exergonic reaction to drive an endergonic reaction
5) a barrier to the initiation of a reaction
This is energy coupling.
1) ATP is hydrolyzed to release its energy
2) the ADP part of ATP is bound to the substrate
3) the terminal phosphate of ATP is bound to the substrate
4) all of the above
The bond between Pi and the substrate preserves much of the energy that was in ATP.
1) links between adenine and sugar are unstable
2) the answer is still unknown
3) peroxide links are highly reactive
4) links between sugar and phosphate are unstable
5) triphosphate chains are unstable
The instability is associated with high energy, favoring reactions that break the triphosphate chain.
1) a: it will be very slow without a catalyst
2) b: the free energy change for the reaction is positive
3) c: equilibrium favors the reactants, not the products
4) both a and c
5) both b and c
If the free energy change for the reaction is positive, equilibrium favors the reactants and say the reaction is unfavorable.
1) a: hydrolysis of ATP releases heat that is used by the unfavorable reaction
2) b: ATP acts as a catalyst to speed the unfavorable reaction
3) c: the unfavorable reaction is replaced by two favorable reactions
4) both a and b
5) both b and c
The first reaction transfers part of ATP to A, making a high-energy product. That product is then converted to B. Both reactions release energy, so both are favorable.
1) a: chloroplast sue light energy to synthesize ATP
2) b: mitochondria synthesize ATP using energy that’s released by oxidizing sugars and fats
3) c: ribosomes use catalytic RNA to couple ADP with Pi
4) both a and b
5) both a, b and c
Plants have both chloroplasts and mitochondria. Animals lack chloroplasts; they get sugars and fats from other organisms to fuel their mitochondria.
1) a: enzymes can be either proteins or RNA molecules
2) b: when a cell makes an enzyme, it makes many copies
3) c: their substrate specificity involves matching of shapes
4) both a and b
5) a, b, and c
There are many copies of each enzyme; they’re usually proteins but sometimes they are RNA; and they only attack substrates that fit the shape and charge of the active site.
1) Enzymes may change shape when they bind substrates;
2) Enzymes provide no energy for the reaction, except collision energy;
3) Enzymes may release substrates.
Enzymes do all these things.
1) a: it cannot influence the specificity of an enzyme
2) b: it moves the reactive portion of the enzyme closer to the substrate
3) c: the enzyme’s active site changes shape to fit the correct substrate but not other molecules
4) both b and c
5) none of the above
The active site of the enzyme will change shape to make a better fit with only the appropriate substrate, which can bring the reactive portion of the enzyme closer to the substrate.
1) protecting the catalysts
2) providing activation energy
3) lowering EA
4) raising the kinetic energy of the reactants
5) none of the above
Enzymes always lower EA, though they may have other effects as well. With a lower EA, more collisions can produce the transition state.
1) High-energy collisions are less common than low-energy collisions.
2) Every reaction step adds to the time required for the overall reaction.
3) Large molecules collide more energetically than small molecules.
4) It takes less energy to break a hydrogen bond than a covalent bond.
5) Very low potential energy tends to make molecules unstable.
Enzymes provide reaction pathways that have low activation energy requirements. This allows low-energy collisions to cause reactions.
1) At some point the bond between the amino acid and the substrate must break.
2) This is probably a case where the enzyme changes the position of equilibrium.
3) There must be an error. Enzymes don’t make covalent bonds with substrates.
4) This is possible in theory, but it’s never been observed.
5) It couldn’t happen. Catalysis doesn’t alter the enzyme.
To work repeatedly, the enzyme must return to its original state at the end of each catalytic cycle. Some steps may form bonds or break bonds between the enzyme and substrate.
5) nucleic acids
Most enzymes are proteins.
1) decreasing the potential energy difference between reactant and product
2) adding energy to a reaction
3) adding a phosphate group to a reactant
4) increasing the potential energy difference between reactant and product
5) reducing activation energy
Enzymes work by reducing energy of activation.
1) increases the activation energy of a reaction
2) is an organic catalyst
3) is a source of energy for endergonic reactions
4) is an inorganic catalyst
5) can bind to nearly any molecule
Enzymes are proteins that behave as catalysts.
2) active sites
This is the name given to the reactants in an enzymatically catalyzed reaction.
1) loses a phosphate group
2) loses energy
3) permanently alters its shape
4) is uncharged
5) is used up
Enzymes are not changed as a result of their participation in a reaction.
1) changing the enzyme’s three-dimensional shape
2) causing enzyme molecules to stick together
3) breaking the covalent bonds that hold the molecule together
4) removing phosphate groups from the enzyme
1) it lowers the activation energy of the reaction
2) it raises the activation energy of the reaction
3) it acts as a reactant
4) it is used once and discarded
1) an enzyme’s function is unaffected by changes in pH
2) enzymes inorganic
3) all enzymes depend on protein cofactors to function
4) enzymes catalyze specific reactions
1) Competitive inhibitors interfere with the enzyme; non-competitive inhibitors interfere with the reactants.
2) Competitive inhibitors bind to the enzyme reversibly; non-competitive inhibitors bind to it irreversibly.
3) Competitive inhibitors change the enzyme’s tertiary structure; non-competitive inhibitors cause polypeptide sub-units to dissociate.
4) Competitive inhibitors bind to the active site of the enzyme; non-competitive inhibitors bind to a different site.