Deck 2: Physical Biochemistry: Energy Conversion, Water, and Membranes

Question 1

The change in entropy of a system is a function of a change in

A) temperature and pressure.
B) volume and pressure.
C) enthalpy and pressure.
D) enthalpy and temperature.

Answer 1

enthalpy and temperature.

Question 2

A hot pack on your arm is an example of what kind of system?

A) open
B) closed
C) isolated
D) surroundings

Answer 2

closed

Question 3

The combustion of gasoline is considered exothermic because heat is

A) transferred from the surroundings to the system.
B) transferred from the system to the surroundings.
C) transferred to the universe.
D) not transferred.

Answer 3

transferred from the system to the surroundings.

Question 4

Given a biological system at 1 atm with $\Delta$ H = 16 kJ/g, what is the internal energy of the system?

A) 15 kJ/g
B) 16 kJ/g
C) 14 kJ/g
D) Not enough information is given to calculate the answer.

Question 5

What chemical process is able to take place in the presence of solar energy?

A) anaerobic respiration
B) photosynthesis
C) hydrogenation
D) hydrolysis

Question 6

The difference between an oxidation reaction and a reduction reaction is that oxidation is the __________ and reduction is the _.

A) loss of electrons; gain of electrons
B) gain of electrons; loss of electrons
C) loss of protons; gain of protons
D) gain of protons; loss of protons

Question 7

Energy conversion in a biological system operates under constant and constant _.

A) heat; pressure
B) work; heat
C) pressure; volume
D) volume; heat

Question 8

Gibbs free energy can best be defined as the

A) difference between the enthalpy and entropy of a system at a given temperature.
B) difference between exothermic and endothermic energy of a system at a given temperature.
C) addition of enthalpy and entropy of a system at a given temperature.
D) difference between pressure and volume at a given temperature.

Question 9

What is the final molecule made from the oxidation of H₂O by solar energy?

A) ozone
B) glucose
C) fructose
D) carbon dioxide

Question 10

Which of the following is the correct solar energy reaction that takes place on the sun?

A) "4 He $\rightarrow$ ⁴He"
B) "⁴He $\rightarrow$ 4 He"
C) "4 H $\rightarrow$ ⁴He"
D) "⁴H $\rightarrow$ 4 H"

Question 11

Energy conversion in living systems is required for what three types of work?

A) osmotic work, chemical work, mechanical work
B) osmotic work, chemical work, potential work
C) kinetic work, chemical work, mechanical work
D) osmotic work, photosynthetic work, mechanical work

Question 12

Given 80 grams of water, how many calories are required to raise the temperature 1 $\degree$ C?

A) 4.184 calories
B) 15.7 calories
C) 80 calories
D) Not enough information is given to calculate the answer.

Question 13

The oxidation of glucose releases 15.7 kJ/g. Is this reaction spontaneous?

A) Yes, because it is exothermic.
B) No, because it is exothermic.
C) Yes, because it is endothermic.
D) The answer cannot be determined.

Question 14

For a reaction to be spontaneous, the change in the entropy of the universe must be

A) greater than zero.
B) less than zero.
C) equal to zero.
D) equal to 1.

Question 15

In the figure below, which state of matter has the highest entropy?

A) solid phase
B) liquid phase
C) gas phase
D) all are equal entropy.

Question 16

Which of the following best describes an open system?

A) Matter and energy are freely exchanged with the surroundings.
B) Energy is exchanged with the surroundings but matter is not.
C) Matter is exchanged with the surroundings but energy is not.
D) Neither matter nor energy is exchanged with the surroundings.

Question 17

The example of water freezing into ice shows

A) an increase in entropy of the system.
B) a decrease in entropy of the system.
C) no change in the entropy of the system.
D) a decrease in the entropy of the surroundings.

Question 18

Which of the following best defines the first law of thermodynamics?

A) All spontaneous processes in the universe tend toward dispersal of energy.
B) Total amount of energy in the universe is a constant.
C) There is no entropy at zero Kelvin.
D) Entropy is a measure of disorder.

Question 19

Which of the following is an example of a system?

A) the universe
B) the air
C) a test tube with reaction components
D) outer space

Question 20

Which of the following correctly describes the relationship between an ice cube melting on the table and the air surrounding it?

A) The ice cube is the system and the air is the surroundings.
B) The air is the system and the ice cube is the surroundings.
C) The ice cube is the system and only the air is the universe.
D) The air is the system and only the ice cube is the universe.

Question 21

A hydrogen bond can form between a hydrogen atom on a(n)

A) electronegative donor group and another electronegative atom.
B) cationic atom and another hydrogen.
C) nonpolar donor group and an electronegative atom.
D) ionic atom and another anion.

Question 22

The __________ system controls the interconversion among ATP, ADP, and AMP.

A) phosphorylate
B) adenylate
C) energy conversion
D) metabolism

Question 23

Organisms on Earth cannot easily exist at temperatures below 0 $\degree$ C because at that temperature

A) hydrogen bonds cannot exist.
B) water does not exist in a tetrahedron.
C) ice crystals form in the organism.
D) proton hopping cannot occur.

Question 24

Given the energy charge equation below, if a biological system has an EC = 0.8, what is true about the concentrations of ATP, ADP, and AMP in the system?

A) The concentrations are all equal.
B) There is more ADP in the system than ATP or AMP.
C) There is more ATP in the system than ADP or AMP.
D) There is more AMP in the system than ATP and ADP.

Question 25

The standard free energy change is defined under what set of conditions?

A) 1 atm, 298 K, 1 M
B) 1 atm, 273 K, 1 M
C) 100 kPa, 273 K, 1 M
D) 100 kPa, 298 K, 1 M

Question 26

What chemical reaction causes ATP to be a high-energy molecule?

A) cleavage of phosphoanhydride bond
B) transfer of an adenylyl group to form a reactive intermediate
C) hydrolysis of phosphoryl group
D) oxidation of phosphoanhydride bond

Question 27

Under steady-state conditions in a mammalian cell, the adenine nucleotide concentrations are [ATP] = 3.3 mM, [ADP] = 1.2 mM, and [AMP] = 0.2 mM. What is the energy charge of this cell?

A) 0.83
B) 0.95
C) 0.72
D) 1.2

Question 28

If a reaction has a $\Delta$ H $\lt$ 0 and $\Delta$ S $\lt$ 0, under which conditions would the reaction be spontaneous in the forward direction?

A) low temperatures
B) high temperatures
C) high pressure
D) low pressure

Question 29

In a hydrogen bond between a water molecule and another water molecule,

A) a hydrogen ion on the water molecule forms an ionic bond with the oxygen ion on the other water.
B) the hydrogen bond typically forms between the oxygen atom of the water and the hydrogen on the other water.
C) a hydrogen on the water molecule forms a covalent bond to a hydrogen atom on the other water.
D) the hydrogen atom forms an ionic bond with a carbon on the other water.

Question 30

If $\Delta$ G= 0 for a reaction, then this reaction

A) is favorable in the forward direction.
B) is favorable in the reverse direction.
C) is at equilibrium.
D) cannot occur.

Question 31

If the Gibbs free energy change value for a reaction is less than zero, this reaction is

A) exergonic.
B) endergonic.
C) exothermic.
D) endothermic.

Question 32

For a given reaction with a $\Delta$ G $\lt$ 0, the reaction is

A) favorable in the reverse direction.
B) favorable in the forward direction.
C) unfavorable in both directions.
D) favorable in both directions.

Question 33

If the equilibrium constant (K_eq) is greater than 1, which direction will the reaction proceed?

A) spontaneously to products
B) spontaneously to reactants
C) neither direction
D) Not enough information is given to determine the direction of reaction.

Question 34

If the equilibrium constant (K_eq) is greater than 1, what is the value of $\Delta$ G $\degree$ ?

A) " $\Delta$ G $\degree$ $\gt$ 0"
B) " $\Delta$ G $\degree$ = 0"
C) " $\Delta$ G $\degree$ $\lt$ 0"
D) " $\Delta$ G $\degree$ $\gt$ 1"

Question 35

If a reaction has a $\Delta$ H $\gt$ 0 and a $\Delta$ S $\lt$ 0, then __________ and the reaction is at all temperatures.

A) " $\Delta$ G $\lt$ 0; spontaneous"
B) " $\Delta$ G $\gt$ 0; spontaneous"
C) " $\Delta$ G $\lt$ 0; nonspontaneous"
D) " $\Delta$ G $\gt$ 0; nonspontaneous"

Question 36

Hydrogen bonds in liquid water are formed between

A) two hydrogen atoms on the same molecule.
B) the oxygen of one molecule and the hydrogen of another.
C) protons and hydroxides.
D) two oxygen atoms on different molecules.

Question 37

Describe how an antifreeze protein functions.

A) Regularly spaced tyrosine residues prevent the ice crystals from growing.
B) Regularly spaced threonine resides prevent the ice crystals from growing.
C) Flickering clusters of hydrogen bonds prevent the ice crystals from growing.
D) The antifreeze protein prevents the water wires from forming.

Question 38

Under what conditions could a biological reaction spontaneously proceed to reactants if the $\Delta$ G $\degree$ $\gt$ 0?

A) Reactant concentrations are greater than product concentrations.
B) Product concentrations are greater than reactant concentrations.
C) Reactant concentrations are equal to product concentrations.
D) There are no conditions where this could happen.

Question 39

The interaction between an amino group and a carboxylate group is best characterized as

A) hydrogen bonds.
B) ionic interactions.
C) van der Waals interactions.
D) a covalent bond.

Question 40

The transfer of a phosphate from ATP to another molecule produces a(n)

A) low-energy intermediate.
B) highly reactive intermediate.
C) neutral energy intermediate.
D) It is not possible to transfer a phosphate to another molecule.

Question 41

Which of the following acids is the strongest given their Ka values?

A) HF (3.5*10^{- 4})
B) HClO₂ (1.1 *10^{- 2})
C) HCN (4.9 * 10^-10)
D) HNO₂ (4.6 *10^{- 4})

Question 42

Calculate the pH of a solution that contains 7.8 *10 ^{- 6} M OH ^- .

A) 1.28
B) 5.11
C) 12.72
D) 8.89

Question 43

The interaction between nonpolar molecules is best characterized as

A) a hydrogen bond.
B) ionic interactions.
C) van der Waals interactions.
D) a covalent bond.

Question 44

Which of the following is true?

A) A neutral solution contains [H₂O] = [H⁺].
B) A neutral solution does not contain any H⁺ or OH^-.
C) An acidic solution has [H⁺] > [OH^-].
D) A basic solution does not contain H⁺.

Question 45

Calculate the pH of a solution that contains 3.9 *10^{- 4}M H⁺.

A) 4.59
B) 10.59
C) 3.41
D) 9.41

Question 46

As a protein folds, what are the stabilizing forces that help keep the protein folded?

A) hydrophilic amino acids on the interior and hydrophobic amino acids on the exterior
B) increase in entropy in the surrounding water
C) favorable change in free energy
D) hydrophobic amino acids on the interior and hydrophilic amino acids on the exterior

Question 47

Freezing point depression, boiling point elevation, and osmotic pressure are all what kind of properties?

A) intrinsic properties
B) colligative properties
C) state functions
D) hydrophobic effects

Question 48

Osmosis occurs when water diffuses through a

A) semipermeable membrane from high water to low water concentration.
B) nonpermeable membrane from high water to low water concentration.
C) semipermeable membrane from low water to high water concentration.
D) semipermeable membrane from high solute to low solute concentration.

Question 49

How do plants, fungi, and bacteria avoid the damaging effects of a hypotonic environment?

A) flexible cells walls
B) rigid cells walls
C) semipermeable cell walls
D) photosynthesis

Question 50

Red blood cells are placed into a solution of unknown solute concentration. After an hour they have all burst open. The best explanation is that the solution

A) had no solutes.
B) had a very high concentration of solutes.
C) had a very high concentration of solvent
D) was at equilibrium.

Question 51

Calculate the concentration of pH of a 0.023 M HCl solution.

A) 12.36
B) 3.68
C) 1.64
D) 2.30

Question 52

Hydrophobic interactions between nonpolar molecules result from the

A) tendency to maximize water's interaction with nonpolar molecules.
B) strong attractions between nonpolar molecules.
C) water becoming more ordered around the nonpolar molecule.
D) water ionically bonding to the nonpolar molecule.

Question 53

An organism in equilibrium with its environment is no longer alive because

A) homeostasis is required for life.
B) heterostasis is required for life.
C) an organism requires only exergonic reactions to be alive.
D) an organism requires only endergonic reactions to be alive.

Question 54

If an unknown solution has low pKa value, it can be said with certainty that it is

A) a weak acid.
B) a strong acid.
C) pure water.
D) a nonpolar solution.

Question 55

What is the concentration of OH ^- in a solution that contains 3.9 * 10^-4 M H^-?

A) 2.6*10^-11 M
B) 3.9 *10^-4 M
C) 2.7 * 10^-2 M
D) 1.0 * 10 ^{- 14} M

Question 56

The effects of solutes on the colligative properties of a solution depend only on the

A) chemical properties of the solutes.
B) molecular mass of the solutes.
C) overall charge of the solute.
D) number of solute particles.

Question 57

What is the expected osmotic pressure around the cells for the plant with low turgor pressure shown below?

A) hypotonic
B) hypertonic
C) isotonic
D) equilibrium

Question 58

Which of the following is the K_w value for pure water at 25 $\degree$ C?

A) 1 *10¹⁴
B) 1 *10^-14
C) 7
D) 14

Question 59

Limonene is a nonpolar molecule. The water molecules around it forms

A) hydrogen bonds with itself and entropy decreases.
B) ionic bonds with itself and the entropy decreases.
C) hydrogen bonds with limonene and the entropy increases.
D) covalent bonds with limonene and entropy increases.

Question 60

What is the concentration of H ⁺ in a solution of 0.05 M NaOH?

A) 5 * 10^-16 M
B) 2 *10^-13 M
C) 5*10¹² M
D) 140 M

Question 61

Calculate the $\Delta$ G $\degree$ for the net reaction given the following two reactions:

Question 62

Justify the following sentence: The conversion of carbon dioxide and water into glucose and oxygen is a decrease of entropy.

Question 63

The endomembrane system encompasses which part of the cell?

A) organelles
B) nucleus
C) cytoplasmic membrane structures
D) entire cell

Question 64

Compare the reaction conditions under which you measure K_eq versus Q.

Question 65

Given a solution with pH > pKa, what are the relative concentrations of A^- and HA?

A) [HA] > [A^-]
B) [HA] < [A^-]
C) [HA] = [A^-]
D) [HA] = [A^-] = 1

Question 66

Calculate the pH of a solution containing 0.105 M HA and 0.146 M A^-. The Ka for the weak acid is 1.8 *10^{- 5}.

A) 4.88
B) 9.11
C) 4.74
D) 7.00

Question 67

Compare the reaction conditions for $\Delta$ G $\degree$ and $\Delta$ G $\degree$ ^' .

Question 68

You wish to prepare a solution with a pH of 5.44. If the pKa of the weak acid is 4.74, what ratio of weak base to weak acid should you use?

A) 0.70
B) 0.20
C) 1.4
D) 5.0

Question 69

The characteristic(s) of a phospholipid is/are that they

A) are overall nonpolar.
B) have a polar charged head group and nonpolar hydrocarbon tails.
C) have a nonpolar head group and polar hydrocarbon tails.
D) are overall polar.

Question 70

A molecule with hydrophobic and hydrophilic properties is best described as

A) a zwitterion.
B) amphipathic.
C) polar.
D) nonpolar.

Question 71

A solution of which of the following would be a good buffer system?

A) HCl and NaOH
B) HCl and H₂O
C) CH₃COOH and NaCH₃COO
D) NaOH and KOH

Question 72

How are polar molecules like glucose transported across a membrane?

A) There are holes in the membrane.
B) There are proteins that allow the transportation of polar molecules across the membrane.
C) Polar molecules cannot ever enter the cell.
D) Polar molecules diffuse across the hydrophobic barrier.

Question 73

Using the figure below, which of the following best describes the titration curve?

A) The equivalence point for the titration is pH = 7.
B) The midpoint of the titration is pH = 7.
C) The pKa for this weak acid is 4.76.
D) This is a titration of a weak base by NaOH.

Question 74

The endomembrane system is/are

A) an intracellular network of lipid bilayers.
B) energy converting organelles.
C) a membrane surrounding the cell.
D) nucleotide-containing membranes.

Question 75

The lateral mobility of lipids with membrane depends on temperature as well as other factors. What would be expected to happen to the lateral mobility if the temperature was decreased?

A) Mobility would be unaffected.
B) Mobility would increase.
C) Mobility would decrease.
D) The membrane would decompose.

Question 76

Which of the following are true about buffers?

A) An effective buffer is made from a strong acid and strong base.
B) A buffer is most resistant to changes in pH when [HA] = [A^-].
C) A buffer is only resistant to changes in pH when acid is added.
D) The pH range of a buffering system is 0 to 14.

Question 77

The fluidity of a membrane depends on

A) the degree of saturation of the phospholipids.
B) the number of phospholipids in the membrane.
C) the size of the polar head group.
D) osmotic pressure.

Question 78

Calculate $\Delta$ G for a reaction given $\Delta$ H = 15.4 kJ/mole and $\Delta$ S = 2.0 J/K at 298 K. Is this reaction spontaneous in the forward direction?

Question 79

The main function of the chloroplast is

A) protein biosynthesis.
B) to attach carbohydrates to lipids.
C) to convert light energy into chemical energy.
D) RNA synthesis.

Question 80

Weak acids have a high pKa because the

A) HA concentration is high.
B) H⁺ concentration is high.
C) A ^- concentration is high.
D) HA concentration is low.