AAMC Sample Full Length 1 Review ?s

Question 1

CP5 Which way should electric field lines flow when depicting an axon against its extracellular fluid?

Answer 1

Electric field lines should exit from positive and enter negative charges. The axon itself is negatively charged. The extracellular solution has zero potential. So the field lines will start in the fluid and put inward to membrane

Question 2

CP7: Atomic Properties: Channel X transmits only the smallest substances dissolved in the extracellular fluid through the axon membrane. What does Channel X transmit? A: proteins B: Na+ ions C: K+ ions D: Cl- ions

Answer 2

-ANS is B Sodium Ions, b/c they are the smallest. Ionic size increases left to right, and top to bottom.

Question 3

Q9: Electrics: What info about an axon is required to calculate the current assosciated with an NCV pulse?

Answer 3

ANS is potential, resistance per unit length, and length. This is obtained by manipulating V=IR to I = V/R. We need V(potential), and to determine R, we can use resistance per unit length and the tota length.

Question 4

_Q11 Takewa_y: How would a weak acid conduct electricity vs. a strong acid?

Answer 4

A weak acid will only partially disassociate into ions, whereas a strong acid will fully disassociate. With more ions in the solution, the strong acid will better conduct electricity.

Question 5

Q14: What is squalene(ring-like structures with lots of double bonds) a precursor of? A:Triacyl glycerols B: Peptide hormones C: Steroid hormones D: Prostaglandins

Answer 5

ANS is C. It looks like cholesterol!

Question 6

Q16: When will a disaccharide react with Ag2O in NH3(aq) and form a precipitate?

Answer 6

If it is a reducing sugar -> it has a hemiacetal group. It will not react if it has an acetal group!

Question 7

Q17: What is the net charge of the peptide Arg-Ala-Phe-Leu at pH 8? -1, 0, +1, or +2?

Answer 7

ANS is +1. Arg is the only charged amino acid at that pH-> it has a charge of +1. The N-terminus itself has a charge of +1, and the C-terminus has a charge of -1. Taken all together, this equals +1.

Question 8

In Reverse Phase HPLC( there is a polar mobile phase and a non polar stationary phase), will a polar compound elute first or non polar?

Answer 8

In Reverse-phase, polar compounds will elute first. Then non-polar compounds will

Question 9

In _normal phase HPLC(_stationary polar phase and non polar mobile phase), will a polar compound elute first or a non polar?

Answer 9

In normal phase, a non polar solvent will elute first.

Question 10

IR Frequency Identities:

I: 1580-1610 cm-1

II: 1700-1750 cm-1

III: 3200-3500 cm-1

Answer 10

I is an aromatic or conjugated system

II is a C=0

III is an OH group

Question 11

How would you use a lens to correct for myopia or near-sightedness?

Answer 11

Use a diverging lens.

This works b/c in myopia the lens incorrectly focuses light on a point before the retina. Using a diverging lens would spread out light, and cause it to hit further back on the retina!

Question 12

Q46: The density of a human body can be calculated form its weight in air, Wair, and its weight while subsmered in water ,Ww. The density of a human body is proportional to:
A: Wair/(Wair-Ww)

B: (Wair-Ww)/Wair

C: (Wair-Ww)/Ww

D:Ww/(Wair-Ww)

Answer 12

-ANS is A: Wair/(Wair-Ww).

Archimedes’ Principle, the ra_tio of density of an object to the density of fluid_ it is submersed in is e_qual to the ratio of weight of the object in air to the difference in submersed weight and weight in air._

Question 13

What is the un_it 1 Watt equivalent to?_

Answer 13

1 Joule /second

Question 14

During glycolysis. Pyruvate(CH3C(=O)CO2 is reduced to lactate CH3CH(OH)CO2- by nicotinamide adenine dinucleodide (NADH). What is the balanced reaction for this conversion?

A: CH3C(=O)CO2- + 2 NADH -> CH3CH(OH)CO2- + 2NAD+

B: CH3C(=O)CO2- + 2 NADH + 2H+ -> CH3CH(OH)CO2- + 2NAD+

C: CH3C(=O)CO2- + NADH + 2H+ -> CH3CH(OH)CO2- + NAD+

D: CH3C(=O)CO2- + NADH + H+ -> CH3CH(OH)CO2- + NAD+

Answer 14

-ANS is D: CH3C(=O)CO2- + NADH + H+ -> CH3CH(OH)CO2- + NAD+.

This can only be arrived at by knowing the reduction of pyruvate is CH3(=O)CO2- + 2H+ + 2e- -> CH3CH(OH)CO2-. Balance is attained by first balancing hydrogen with H+(adding two H+s to the reactant side ) and then the charge with e-(adding two to the reactant side). The oxidation half reaction is NADH -> NAD+ + H+ + 2e-. Adding these together, the e- cancel out.

Question 15

Hydrolysis of the gamma phosphate of GTP bound to Arf1(or most substrates in general) results in:

A: denaturation

B: activation

C: inactivation

D: membrane assosciation

Answer 15

ANS is C inactivation. Hy_drolysis of GTP_ would result in formation of GDP in the pocket.

Question 16

The cutting of introns and the splicing assosciated with the expression of Factor VIII gene occur during wihhc of the following steps in protein-synthesis process?

A: DNA -> mRNA

B: DNA -> tRNA

C: mRNA -> tRNA

D: tRNA -> protein

Answer 16

ANS is A DNA->mRNA. Removal of introns and splicing of the remaining pieces(exons) is a step in the production of mature mRNA from the transcript produced from DNA.

Question 17

Organic acids, denoted by HA, are only minimally deprotonated when added to pure water.

HA(aq)<->H+(aq) + A-(aq)

When dissolved in blood however, HA fully dissosciate. What factor can be used to explain this discrepancy?

A: In blood, the concentration of H+ is maintained at low levels by other equilibria.

B: In blood, the reaction is coupled to ATP hydrolysisis to make it more favorable.

C: In blood, the ionic strength of the solvent medium is much higher than pure water

D: In blood, enzymes are used to catalyze the dissociation reaction.

Answer 17

ANS is A in blood, [H+] is maintained at low levels by other equilibria.

The chemical equation shows that H+ is a product of the reaction. Due to Le Chatelier’s principle, the equilibrium will favor products when the concentration of products is kept low.

Question 18

In oxidative phosphorylation, cytochrome c carrys how many electrons as?

Answer 18

As a 1-electron carrier. It is a heme protein that cycles between ferrous and ferric state. Therefore, it can only do single electron transfers.

Question 19

Which primer is most suitable for PCR?

A: 5’-ATTACGTTAACATGAAG-3’

B: 5’-ATATCGTTAACAAATTG-3’

C: 5’-GCTATAAAGATTGCAAA-3’

D: 5’-GCATAGAAGCATTCCGC-3’

Answer 19

-ANS is D b/c good primers have high GC content and have G or C base pairs at 5’ and 3’ ends.

Question 20

In what phase of meiosis does nondisjunction occur?

A: Anaphase I

B: Metaphase II

C: Prophase I

D: Telophase II

(It occurs in one other phase than listed too)

Answer 20

A, Anaphase I.

Nondisjunction is the failure of homologous chromosomes to separate during anaphase I of meiosis

+

and/or the failure of sister chromosomes to separate during anaphase II of meiosis.

Question 21

Which stereoisomer of proteins exists predominatly in the wild and is incorporated by ribosomes?

D or L?

Answer 21

L isomers are used by ribosomes.

D isomers cannot be incorporated…

Question 22

If a cereberal malaria-causing infected erthtrocyte lost its adhesion to endothelium in brain venules, it would most likely first flow into which type of blood vessels?

A: Arterioles

B: Veins

C: Capillaries

D: Arteries

Answer 22

B veins. The passage mentioned that they were in venules. It would come as a result that they would flow into the veins downstream.

Question 23

When a striated muscle cell metabolizes glucose in the complete absence of O2, which of the following substances is NOT produced in a significant amount?

A: Pyruvic acid

B: Glucose-6-phosphate

C: Lactic acid

D: Acetyl-CoA

Answer 23

D Acetyl-CoA. In the absence of oxygen, pyruvate will be converted to lactate in the cytoplasm and won’t be transported to the mitochondria. The absence of O2 will induce lactic acid fermentation.