Chemistry Yr 2 Nm Sem 2

Front 1

In the International System of Units, the unit of energy is the:

A. Calorie

B. Degree

C. Coulomb

D. Newton

E. Joule

Back 1

E. Joule

Front 2

If heat is absorbed by the system during a chemical reaction, the reaction is said to be
A. Exergonic
B. Endergonic
C. Exothermic
D. Endothermic
E. At equilibrium

Back 2

D. Endothermic

Front 3

The enthalpy change ΔH for the formation of ammonia from hydrogen and nitrogen is -46.11 kJ/mol. This reaction is:
A. Exergonic
B. Endergonic
C. Exothermic
D. Endothermic
E. At equilibrium

Back 3

C. Exothermic

Front 4

If the ΔG°' of the reaction A → B is -40kJ/mol, the reaction:
A. Will proceed spontaneously from left to right.
B. Will never reach equilibrium.
C. Will proceed at a rapid rate.
D. Is at equilibrium.
E. Will not occur spontaneously.

Back 4

A. Will proceed spontaneously from left to right.

Front 5

Which of the following compounds has the largest negative value for the standard free energy change (ΔG°') upon hydrolysis?
A. Phosphoenolpyruvate
B. Glucose
C. Glucose-6-phosphate
D. Glycerol
E. Glycerol-3-phosphate

Back 5

A. Phosphoenolpyruvate

Front 6

All of the following contribute to the large negative free-energy change upon hydrolysis of the “high-energy” compounds except:
A. Electrostatic repulsion in the reactant.
B. Stabilization of products by ionization.
C. Low activation energy of the forward reaction.
D. Stabilization of products by isomerisation.
E. Stabilization of products by extra resonance forms.

Back 6

C. Low activation energy of the forward reaction.

Front 7

The term “high–energy bond” refers to
A. One that cannot be broken below 80°C.
B. A bond that requires input of at least 100kJ/mol.
C. One for which hydrolysis releases a useful amount of energy.
D. The anhydride bond in ATP only.
E. One with a high activation energy of forward reaction.

Back 7

C. One for which hydrolysis releases a useful amount of energy.

Front 8

The hydrolysis of ATP can be used to drive reactions that have a ΔG°' that is
A. Greater than +30.5 kJ/mol.
B. Less than +30.5 kJ/mol.
C. Between +20 and + 40kJ/mol.
D. Greater than +40kJ/mol.
E. All of the above.

Back 8

B. Less than +30.5 kJ/mol.

Front 9

Which of the following compounds that are found in the cell does not have a large negative free energy of hydrolysis?
A. Thioesters such as acetyl CoA.
B. Phosphoenolpyruvate.
C. 1, 3-diphosphoglycerate.
D. 3-phosphoglycerate.
E. Adenosine diphosphate (ADP).

Back 9

D. 3-phosphoglycerate.

Front 10

The standard free energy changes for the reactions below are given

Phosphocreatine → creatine + Pi ΔG°' = 43.0kJ/mol

ATP → ADP + Pi ΔG°' = -30.5kJ/mol

What therefore is the overall ΔG°' for the following reaction?

Phosphocreatine + ADP → creatine + ATP

A. -12.5kJ/mol
B. +12.5kJ/mol
C. -74kJ/mol
D. +74kJ/mol
E. The ΔG°' cannot be calculate without the equilibrium constant (Keq').

Back 10

A. -12.5kJ/mol

Front 11

The hydrolysis of ATP has a large negative ΔG°', nevertheless the molecule is stable in solution. This stability is due to:

A. Resonance stabilization.
B. Entropy stabilization.
C. The hydrolysis reaction having a large activation energy.
D. Ionization of the phosphates.
E. The hydrolysis reaction being endergonic.

Back 11

C. The hydrolysis reaction having a large activation energy.

Front 12

According to the equation ΔG = ΔH – T ΔS, a reaction can be spontaneous under all the following conditions, except:

A. When ΔH is positive and ΔS is negative.
B. When ΔH is negative and ΔS is positive.
C. When both ΔH and ΔS are negative.
D. When both ΔH and ΔS are positive.
E. Any of these conditions can exist in a spontaneous reaction.

Back 12

A. When ΔH is positive and ΔS is negative.

Front 13

Gibbs free energy is the energy available to do work at:

A. Constant pressure.
B. Constant volume.
C. Constant temperature.
D. Constant pressure and temperature.
E. All of these are correct.

Back 13

D. Constant pressure and temperature.

Front 14

The value of ΔG equals zero when:

A. The reaction is just getting started.
B. The reaction has gone to completion.
C. Equilibrium has been reached.
D. The reaction has gone to completion and equilibrium has been reached.
E. All of these are correct.

Back 14

C. Equilibrium has been reached.

Front 15

Almost all of the oxygen (O2)one consumes in breathing is converted to:

A. Carbon dioxide (CO2)
B. Carbon monoxide (CO) and then to carbon dioxide
C. Water
D. Acetyl CoA
E. None of the above

Back 15

B. Carbon monoxide (CO) and then to carbon dioxide

Front 16

The conversion of NAD+ to NADH is an example of reduction because

A. The pyridine ring loses electrons (and a hydrogen).
B. The pyridine ring gains electrons (and a hydrogen).
C. The adenine ring loses electrons.
D. The adenine ring gains electrons.
E. The ribose moiety phosphate group of adenine is lost.

Back 16

B. The pyridine ring gains electrons (and a hydrogen).

Front 17

In the coenzyme FAD the site to which electrons are transferred is:

A. The ribose moiety of the molecule.
B. The purine ring system.
C. A pyrimidine ring system.
D. A nitrogen-containing ring system.
E. The ribitol pentose alcohol.

Back 17

D. A nitrogen-containing ring system.

Front 18

The coenzyme NADPH differs from NADH because it

A. Is the oxidised form of NADH.
B. Contains a thiol group.
C. Contains ribose in an open chain form.
D. Loses the amide group.
E. Has an additional phosphate group.

Back 18

E. Has an additional phosphate group.

Front 19

Most of the reaction of electron transport in the mitochondria occurs?

A. In the outer membrane.
B. In the inner membrane.
C. In the mitochondrial matrix.
D. In the intermembrane space.
E. It is not known where electron transport takes place

Back 19

B. In the inner membrane.

Front 20

The oxidation of a particular hydroxyl substrate to a keto product by mitochondria has a P/O ratio of 2. The initial oxidation step is very likely directly coupled to the:

A. Reduction of a pyridine nucleotide.
B. Reduction of a flavoprotein.
C. Oxidation of a pyridine nucleotide.
D. Oxidation of a flavoprotein.
E. Reduction of cytochrome a3.

Back 20

B. Reduction of a flavoprotein.

Front 21

If the mitochondrial electron carriers are artificially oxidised and NADH is then added to the system, the last carrier to become reduced is:

A. Cytochrome a3.
B. Coenzyme Q.
C. Cytochrome b.
D. Flavoprotein.
E. Ubiquinone.

Back 21

A. Cytochrome a3.

Front 22

Because multiple steps are involved in electron transport, the following occurs:

A. By using several steps the net –ΔG is higher (more energy is released).
B. More heat can be generated by using small steps.
C. More energy can be captured to synthesize ATP by small steps.
D. Small steps allow for both more heat generation and more ATP synthesis.
E. All of these statements are true.

Back 22

C. More energy can be captured to synthesize ATP by small steps.

Front 23

Succinate dehydrogenase is located in which complex of the mitochondrial respiratory chain?

A. Complex I.
B. Complex II.
C. Complex III.
D. Complex IV.
E. It is not known where succinate dehydrogenase is located.

Back 23

B. Complex II.

Front 24

The only complex which actually uses oxygen in mitochondrial respiratory chain is:
A. Complex I.
B. Complex II.
C. Complex III.
D. Complex IV.
E. It is not known where oxygen is used.

Back 24

D. Complex IV.

Front 25

If electron transfer in tightly coupled mitochondria is blocked with antimycin A between cytochrome b and cytochrome c, then:

A. ATP synthesis will continue, but the P/O ratio will drop to 1.
B. Electron transfer from succinate to O2 will continue unabated.
C. Electron transfer from NADH will cease, but O2 uptake will continue.
D. Energy diverted from the cytochromes will be used to make ATP, and the P/O ratio will rise.
E. All ATP synthesis will stop.

Back 25

E. All ATP synthesis will stop.

Front 26

The electron carriers in electron transport which are not membrane-bound include:
A. Cytochrome c
B. Coenzyme Q
C. Oxygen (O2)
D. Cytochrome c and coenzyme Q
E. All of these are electron carriers that are not membrane bound

Back 26

A. Cytochrome c