Week 3

Refer to Animation: Oxidation-Reduction Reactions. The reaction of iron with oxygen to form iron oxide is an example of an oxidation-reduction reaction: 4Fe + 3O2 → 2Fe2O3. In this reaction ______ loses electrons and is _________. Fe2O3; reduced O2; reduced O2; oxidized Fe; oxidized Fe; reduced

Fe; oxidized

The carbon atom in CO2 shares _______ electron pairs. After the reaction with H2O to form H2CO3 is completed the carbon atom shares ________ electron pairs. four; four two; three three; two two; two

four; four

Which of the choices is an example of kinetic energy? a ball at the top of stairs gasoline in an auto gas tank a photon of light a C-H bond in a sugar molecule water behind a dam

a photon of light

When H2CO3 reacts to form CO2 and H2O, what is the net change in the number of shared electron pairs? -3 0 +2 -2

0

Nicotinamide adenine dinucleotide is an electron carrier in many important cellular reactions. It exists in an oxidized form (NAD+) and a reduced form (NADH). What is the missing component in the reaction: NAD+ + ____ + H+ → NADH? 2e- heat O2 4e- H2O

2e-

An example of potential energy is a ball sitting _____ of the stairs. All of these choices are correct. in the middle at the bottom at the top

All of these choices are correct.

Which of the choices is considered a form of kinetic energy? wind a rolling ball All of these choices are correct. heatlight

All of these choices are correct.

Which of the statements is true of allosteric inhibitors of an enzyme? Allosteric inhibitors increase the rate of enzyme activity. Allosteric inhibitors decrease enzyme activity. Allosteric inhibitors are structurally similar to the normal substrate of an enzyme. Allosteric inhibitors bind to the active site of the enzyme.

Allosteric inhibitors decrease enzyme activity.

Many cellular processes represent work that requires the expenditure of energy. Which of the actions is not a cellular process that requires the cell to expend energy? Diffusion of water into cells. Synthesis of large biomolecules like proteins and nucleic acids. Keeping sodium ion concentration lower inside a cell than outside the cell. Contraction of muscle cells.

Diffusion of water into cells.

Which statement is true about exergonic reactions? There is a positive ΔG. The products of exergonic reactions have more free energy than the reactants. Energy is released from the reactants.

Energy is released from the reactants.

Which example represents the reduced forms of the two major electron carriers? NADH and FAD NADH and FADH2 NAD+ and FADH2 NAD+ and FAD

NADH and FADH2

Refer to Animation: Oxidation-Reduction Reactions. The reaction of iron with oxygen to form iron oxide is an example of an oxidation-reduction reaction: 4Fe + 3O2 → 2Fe2O3. In this reaction ______ gains electrons and is _________. Fe2O3; reduced Fe; oxidized O2; reduced O2; oxidized Fe; reduced

O2; reduced

A carbohydrate such as glucose has a great deal of ______ energy. kinetic potential heat entropy work

Potential

Which of the factors accounts for the higher potential energy of C-C and C-H bonds compared to C-O and H-O bonds? The C-C and C-H bonds are weak, thus requiring a lot of energy to hold together. The C-O and H-O bonds are strong, thus requiring a lot of energy to hold together. The C-C and C-H bonds are strong, thus requiring a lot of energy to hold together. The C-O and H-O bonds are weak, thus requiring less energy to hold together.

The C-C and C-H bonds are weak, thus requiring a lot of energy to hold together.

In a reaction, enzymes change the: ΔG. first law of thermodynamics. types of products. second law of thermodynamics. activation energy.

activation energy.

You notice that a chemical reaction in your system is happening at a slow rate. You want to speed up the reaction. What do you do? add an enzyme that catalyzes the reaction change the ΔG for the reaction increase the activation energy add more products

add an enzyme that catalyzes the reaction

Which of the choices is an example of potential energy? contraction of a muscle cell an electrochemical gradient across the cell membrane chemical transport, as in the sodium-potassium pump flow of calcium ions through a membrane channel

an electrochemical gradient across the cell membrane

Which of the processes requires energy input in the form of ATP? catabolism anabolism

anabolism

Which labeled arrow in the figure represents the activation energy (EA)? arrow c arrow e arrow a arrow d arrow b

arrow b

If you added an enzyme that catalyzes the reaction shown, you would predict that ____ would be reduced but ____ would remain the same. arrow e; arrow c arrow d; arrow e arrow b; arrow c arrow e; arrow b arrow b; arrow e

arrow b; arrow e

Which labeled arrow in the figure represents the change in free energy of the reaction (G)? arrow a arrow d arrow b arrow c arrow e

arrow e

When chemical reactions occur the _____ but the _____. atoms retain their identities; arrangement of bonds changes identity of atoms changes; arrangement of bonds is retained number of bonds per atom changes; total number of bonds is retained

atoms retain their identities; arrangement of bonds changes

The transition state is that portion of the progress of a chemical reaction with a large amount of energy found in _______ reactions. endergonic both endergonic and exergonic exergonic non-spontaneous

both endergonic and exergonic

Anabolic pathways of metabolism are pathways that make large quantities of ATP release stored chemical energy build complex molecules from simple one stake place primarily in skeletal muscles

build complex molecules from simple one

The first phase of glycolysis requires the input of two ATP molecules. It is therefore: reducing. endergonic. oxidative. exergonic.

endergonic.

Week 3 Activation Energy In this figure the solid blue curve plots free energy of a reaction against progress of that reaction. This reaction is: exergonic. More information is needed in order to answer this question. endergonic.

endergonic.

The first law of thermodynamics states that: there is an increase in disorder in the universe over time. only eukaryotic cells can produce ATP. combustion engines are 100% efficient. energy cannot be created or destroyed.

energy cannot be created or destroyed.

The reaction of iron with oxygen to form iron oxide is an example of an oxidation-reduction reaction: 4Fe + 3O2 → 2Fe2O3. In this reaction each iron atom will: lose 1½ electrons. gain 3 electrons. gain 1½ electrons. gain an oxygen. lose 3 electrons.

lose 3 electrons.

Spontaneous reactions have a _____ ΔG. zero negative positive

negative

A molecule that is _____ loses electrons, and a molecule that is _____ gains electrons. None of the other answer options is correct. weak; polar reduced; oxidized negative; positive oxidized; reduced

oxidized; reduced

In cellular respiration, glucose is _____ to CO2 and oxygen is _____ to water. phosphorylated; deoxygenated reduced; oxidized oxidized; reduced deoxygenated; phosphorylated oxidized; oxidized

oxidized; reduced

When chemical reactions occur the _____________ but the _____________. pairing of atoms that share electron pairs changes; individual atomic nuclei stay the same number of shared electron pairs is unchanged; number of atomic nuclei changes number of protons and neutrons changes; shared electrons stay the same

pairing of atoms that share electron pairs changes; individual atomic nuclei stay the same

Which stages of cellular respiration produce CO2 as a waste product? All four stages produce CO2. citric acid cycle and oxidative phosphorylation pyruvate oxidation, and the citric acid cycle glycolysis, pyruvate oxidation and the citric acid cycle glycolysis and pyruvate oxidation

pyruvate oxidation, and the citric acid cycle

Week 3: Oxidation-Reduction The reactions shown present the overall oxidation-reduction reaction in which elemental iron and molecular oxygen react to form iron oxide (A), and also the half reactions showing the oxidation part and the reduction part (B & C).Compare this reaction and its half reactions to the reaction of nicotinamide adenine dinucleotide as an electron carrier in many important cellular reactions:NAD+ + 2e- + H+ → NADHWhich reaction or half reaction is most similar to this NAD+/NADH reaction? reaction B reaction C reaction A it combines both reaction B and reaction C

reaction C

The _____ forms of the electron carriers NAD+/NADH and FAD/FADH2 have high potential energy. reduced oxidized

reduced

Reactions in which there is a negative change in free energy (-ΔG) are: spontaneous and endergonic. nonspontaneous and endergonic. spontaneous and exergonic. nonspontaneous and exergonic.

spontaneous and exergonic.

In glycolysis, ATP is synthesized by: both substrate level and oxidative phosphorylation. redox reactions. oxidative phosphorylation. electron carriers. substrate-level phosphorylation.

substrate-level phosphorylation.

Gibbs free energy is defined as: spontaneous energy. the amount of entropy. the amount of energy lost as heat. the amount of potential energy in a system. the amount of energy available to do work.

the amount of energy available to do work.

In eukaryotic cells, glycolysis occurs in: the endoplasmic reticulum. the matrix of the mitochondria. the cytoplasm. vacuoles. the nucleus.

the cytoplasm.

Table sugar can burn in the reaction if ignited: C6H12O6 + 6O2 → 6CO2 + 6H2O and in the process some potential energy of the sugar becomes kinetic energy. Which of the choices represents kinetic energy from this reaction? the products and their surroundings have more heat some of the sugar becomes energy the products are simpler than the starting molecule

the products and their surroundings have more heat

The second law of thermodynamics states that: there is an increase in disorder in the universe over time. energy cannot be created or destroyed. the universe becomes more orderly over time. combustion engines are 100% efficient. only eukaryotic cells can produce ATP.

there is an increase in disorder in the universe over time.

What are the functions of an enzyme? Select all that apply. to alter the equilibrium of a specific reaction to alter the ΔG of a specific reaction to allow a reaction to be reversible to lower the activation energy for the reaction to increase the rate of a specific reaction

to lower the activation energy for the reaction to increase the rate of a specific reaction

The highest free energy is found in the _____(s) of a reaction. end product transition state starting substrate

transition state

The phosphorylation of glucose during glycolysis serves to:Select all that apply. trap imported glucose inside the mitochondria. reduce an electron carrier, storing energy for later. trap imported glucose inside the cell. destabilize the molecule, making it easier to cleave.

trap imported glucose inside the cell. destabilize the molecule, making it easier to cleave.

At the end of glycolysis, the carbon originally found in the starting glucose molecule is now present in: one pyruvate molecules.two ATP molecules and two NADH molecules. four ATP molecules and two pyruvate molecules. two pyruvate molecule. two NADH molecules and two pyruvate molecules.

two pyruvate molecule.