Equation Test 1

1. The term used to indicate the degree of randomness within a system is

Enthalpy

Entropy

H-TS

Q/T

Delta G

2. If gas molecules in an enclosed space are allowed to enter a second chamber, the resulting redistribution of gas molecules represents an increase in

Enthalpy

Entropy

Force

Enthalpy and force

All of the rest

3. Amphiphilic molecules:

Have both oxidizing and reducing groups

Have chromophores in two different wavelength regions

Have both acidic and basic groups

Have both hydrophilic and hydrophobic groups

Are micelles

4. In a hydrogen bond between a water molecule and another biomolecule:

A hydrogen ion on the water molecule forms an ionic bond with a hydride ion on the other molecule

The hydrogen bond will typically form between a hydrogen atom and either a nitrogen, sulfur, or oxygen atom

A hydrogen on the water molecule forms a covalent bond to a hydrogen atom on the other molecule

The hydrogen atom is located between an oxygen atom of the water and a carbon atom of the other molecule

5. Assuming you had a way to measure the amount of protein in a sample of food, which of the following elements would you measure in order to tell whether the food contained protein

Oxygen

Hydrogen

Potassium

Carbon

Nitrogen

6. The biological classification system categorizes organisms into the domains:

Bacteria, eukarya, and vertebrate

Archaea and eukarya

Bacteria, eukarya, and archaea

Eukarya and bacteria

None of the rest

7. The strongest non-covalent interactions are:

Van der Waal forces

London dispersion forces

Hydrogen bonds

Dipole-dipole interaction

Ionic interactions

8. The Henderson-Hasselbalch equation, pH = pK + log {[A-] /[HA]} , indicates that when the _____ of a solution containing acid is equal to the _________ of that acid, then the acid is half deprotonated.

PH and pK

Base and OH-

Log pH and log pOH

H+ and pK

Log [A-] and pH

9. Hydrogen bonds within liquid water:

Are attractions between the protons of the oxygen nuclei

Are dipole-dipole attraction

Are ion-induced dipole attractions

Are attractions between two hydrogen atoms

Are attractions between the H(+) and OH(-) ions of the liquid

10. Phosphate, with a pK2 of 6.82, will be mostly in the HPO4(2-) form at pH 7.2. At pH 5.82 it is mostly in the _________________________ forms.

H3PO4

H2PO4(1-)

HPO4(2-)

PO4(3-)

None of the rest

11. A phosphate buffer solution at a pH = pK1 = 2.15 would have equal amounts of phosphate in the ____________ form and the H2PO4(1-) form.

HPO4(2-)

H2PO4(1-)

H3PO4

Disordered

Tetrahedral

12. To make a phosphate buffer at pH 6.82 starting with one liter of 10 mM phosphoric acid (H3PO4; pKs are of 2.15, 6.82, and 12.38), you could add

5 millimoles of HCL

20 millimoles of K+

25 millimoles of HCL

15 millimoles of KOH

You can't make a buffer by adding HCL or KOH

13. The free energy change for the reaction A => B at 25 degree C. Given enthalpy (kJ.mol-1) and entropy (J.K-1.mol-1) for A and B are: A enthalpy = 60; entropy = 22; B enthalpy = 75; entropy = 97. Zero degree C = 273 Kelvin. Delta G = Delta H Ð T Delta S.

-7.4 kJ.mol-1

7.4 kJ.mol-1

-3.7 kJ.mol-1

3.7 kJ.mol-1

None of the rest

14. A solution of buffer at a pH of 8.5 with a pK = 7.5 would have more capacity to buffer the addition of

Acid versus base

Base versus acid

PO4(3-)

HPO4(2-) and PO4(3-)

None of the rest

15. Which of the following statements about water is incorrect?

Water is an excellent solvent for polar molecules.

Pure water has a concentration of approximately 55.5 M.

Non-polar molecules do not dissolve in water, but form a separate phase.

Cations (e.g. Na+) are solvated by shells of water molecules oriented with their hydrogen atoms pointed toward the ions.

16. To make an acetate buffer at pH 4.76 (pK = 4.76) starting with 500 mL of 0.1 M sodium acetate (pK = 4.76), you could add:

0.1 moles of HCL

0.025 moles of HCL

You can't make a buffer by adding HCL or NaOH

0.1 moles of NaOH

0.2 moles of HCL

17. What is the ratio of citric acid (pK1=3.09) to monosodium citrate in a 1.0 M citric acid solution with a pH = 2.09?

10:11

1:11

10:1

1:1

1:10

18. Given log (0.00001)=-5; log(0.0001)=-4; and log(0.001)=-3. If you added a drop (about 0.05 mL) of 1.0 M HCL to one liter of pure water (assume pH 7.), the pH would become:

7.0 (there would be no significant change)

4.3

5.0

2.7

9.7

19. A soccer coach keeps a couple of instant cold packs in her bag in case one of her players suffers a muscle injury. Instant cold packs are composed of a plastic bag containing a smaller water bag and solid ammonium nitrate. In order to activate the fold pack, the bag is kneaded until the smaller water bag breaks, which allows the released water to dissolve the ammonium nitrate. Which of the following statements about the dissolution of ammonium nitrate in water is correct?

Delta G > 0

Delta S > 0

Delta H < 0

Delta T > 0

Delta H < Delta S

20. A spontaneous process

Occurs without the addition of free energy

Has a delta G < 0

Is exergonic

All of the rest

None of the rest

21. An increase in disorder

Is found in every exergonic process

Is characteristic of a system increasing in enthalpy

Is required for a process to be spontaneous

Results in a decrease in entropy

Results in the factor T delta S being positive

22. Hydrophobic interactions between nonpolar molecules or groups:

Result from the tendency to maximize waterÕs contact with nonpolar molecules

Require the presence of surrounding water molecules

Are the result of strong attractions between nonpolar regions

Are the result of strong repulsion between water and nonpolar regions

Depend on strong permanent dipoles in the nonpolar molecules

23. What is the final pH of a solution with 50 mL of a stock solution of 2.0 M K2HPO4 and 25 mL of a stock solution of 2.0 M KH2PO4; diluted to a final volume of 200 mL. (pK=6.82; log(1) = 0; log(2)=0.3; log(3)=0.48; log(5)=0.7).

6.82

6.52

7.12

5.82

7.3

24. Which of the following statements concerning prokaryotes is false?

Prokaryotes are generally much smaller than the eukaryotic cells

Prokaryotes are one branch of the newer, more accurate phylogenic tree made up of prokarya, archaea and eukarya

Prokaryotes do not have organelles

None of the rest

25. Which of the following is a similarity between all prokaryotes and all eukaryotes?

Both contain DNA in a nucleus

Both contain certain of the same membrane bound cell organelles (like mitochondria, Golgi complexes etc)

Both have a cytoskeleton

All of the rest are similarities between prokaryotes and eukaryotes

None of the rest are similarities between prokaryotes and eukaryotes

"None of the rest are similarities between prokaryotes and eukaryotes" was also accepted

Explanation

"None of the rest are similarities between prokaryotes and eukaryotes" was also accepted