FULL LENGTH #2 (AAMC Sample)

What is the concentration of Cl- ions in a 0.1 M solution of calcium chloride?

0.20 M the formula for calcium chloride is CaCl2 and it produces twice as many Cl- ions as Ca2+ ions in solution when it dissolves.

Question #167: A novel compound was developed which occupies the site on STx where GPP130 binds the toxin. A drug with which value of Kd for binding to STx is most effective?

0.25 mM the Kd for the compound and STx must be below the Kd of STx and GPP130. The lower the Kd of the drug, the more effective it will be at inhibiting the interaction between STx and GPP130 because it will bind to STx instead of STx binding to GPP130

Question #52: What is the frequency of the emitted gamma photons? (Note: Use Planck's constant h = 6.6 x 10-34 Js and the elementary charge e = 1.6 x 10^-19 C.) In passage: 99mTc decays to 99Tc by emitting 140-keV gamma photons detected by a suitable camera.

3.38 × 1019 Hz multiply elementary charge by given keV: (1.6x 10^-19 C)(140x10^3) = 2.24 x 10^-14 rearrange equation: E=hf f=E/h, so (2.24 x 10^-14) / (6.62 x 10 ^-34) = 3.38 × 1019 Hz

The average human body contains approximately 5 liters of blood. If the blood has a density of 1060 kg/m3, what is the total mass of blood in the average human? (Note: 1 L = 1000 cm3.)

5.30 kg m = ρV = 1060 kg/m3 × 5 L × 1000 cm3/L × 1 m3/10^6 cm3 = 5.30 kg.

In oxidative phosphorylation, cytochrome c acts as:

A. 1-electron carrier. cytochrome c is a heme protein that only cycles between a ferrous and ferric state during oxidative phosphorylation. Therefore, only single electron transfers are possible.

A college student is late for class and is running down the stairs with several textbooks. The student falls, dropping all of the books. The student is most likely to receive help if:

A. only one other student was present when the accident occurred. bystander effect, which refers to the observation that an individual who needs assistance will be less likely to be helped (or receive needed help more slowly) as the number of people nearby increases.

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

Acetyl-CoA in the absence of oxygen, pyruvate is converted to lactate in the cytoplasm and is not transported to the mitochondria to be converted to acetyl-CoA.

Yeast cells can grow under either aerobic or anaerobic conditions. If the same concentration of glucose were used to grow two different yeast colonies, would the growth rate be faster under aerobic or anaerobic conditions?

Aerobic, because a much greater amount of ATP would be produced to provide energy for reproduction under aerobic conditions, cellular respiration will be used to produce energy, which nets 38 ATP per molecule of glucose. Under anaerobic conditions, fermentation will be used to produce energy, which nets only 2 ATP per molecule of glucose. Because energy stored in ATP is required for nearly all cellular processes including growth, a yeast colony containing cells that produce more ATP would be expected to have a higher growth rate.

In which phase of meiosis does nondisjunction occur?

Anaphase I by definition, nondisjunction is the failure of homologous chromosomes to separate during anaphase I of meiosis or the failure of sister chromosomes to separate during anaphase II of meiosis.

The advantage of the Doppler ultrasound technique over the standard ultrasound technique is that it also allows: measuring the blood flow.

Doppler ultrasound takes advantage of the Doppler Effect in which a sound wave emitted by, or reflected from a moving object, will change its frequency based on the relative speed of the object, in this case, the flow of blood in a vessel.

Which amino acid is neutral, but zwitterionic at pH 7, despite possessing two nitrogen atoms in its formula?

Gln of the amino acids that contain two nitrogen atoms, only asparagine, glutamine, and tryptophan carry an equal amount of positive and negative charge at neutral pH. Of the options listed, only glutamine appears.

The amino acids Asp6, Asn9, Thr10, His11, and Arg27 are found near the ADP binding site of PanK3. Which two amino acids contribute to the stabilization of ADP binding described in the passage?' His11 and Arg27

His and Arg side chains can carry a positive charge. They would have favorable ionic interactions with the negatively charged phosphates of ADP.

During Trial 5, the wire was heated from 293 K to 673 K while V was held constant at 28 V. How did the current through the circuit change during this time?

It decreased from 4.6 A to 2 A. If the temperature T increases by a factor of 673/293 ≅ 2.3, the resistance R will increase by the same amount. From Ohm's Law, current and resistance are inversely proportional, thus current will decrease by a factor of 2.3, from 4.6 A to 2 A.

In humans, the lining of which structure is NOT primarily derived from the endoderm? A. Mouth B. Bronchi C. Bladder D. Stomach

Mouth most of the lining of the mouth is derived from an invagination of ectoderm. Most of the epithelial tissues inside the body (B, C, D) are derived from endoderm.

Channel X transmits only the smallest substances dissolved in the extracellular fluid through the axon membrane. Which substance does Channel X transmit?

Sodium ions because sodium cations are the smallest of the species listed. You can use the periodic table to establish that sodium ions are smaller than either potassium or chloride ions.

Addition of which disaccharide to a solution of Ag2O in NH3(aq) will NOT result in the deposition of shiny silver mirror on the walls of the reaction vessel?

Sucrose sucrose does NOT possess a hemiacetal functional group, will NOT undergo mutarotation, and will NOT be oxidized by Ag+. Saccharides undergo mutarotation if they are capable of ring-opening. The process of ring-opening occurs at a hemiacetal group, and the intermediate is an aldehyde. Such sugars are termed "reducing sugars" as a result of their ability to be oxidized by Ag+.

When choosing a buffer to use for an experiment conducted at pH 5.3, it would be best to choose one with a pKa of: A.) 2.14. B.) 4.75. C.) 6.5. D.) 7.0.

The answer is B because good experimental design protocols state that a good buffer has a pKa within 1 pH unit of the desired experimental conditions.

During glycolysis, pyruvate CH3C(=O)CO2- is reduced to lactate CH3CH(OH)CO2- by nicotinamide adenine dinucleotide (NADH). What is the balanced reaction for this conversion? CH3C(=O)CO2- + NADH + H+ → CH3CH(OH)CO2- + NAD+

The answer to this question is D, which can only be arrived at by using half-reactions. The balanced half-reaction for the reduction of pyruvate is CH3C(=O)CO2- + 2H+ + 2e-→ CH3CH(OH)CO2-. Balance was attained by first balancing hydrogen with H+ (adding two H+ to the reactant side) and then the charge with e- (adding two to the reactant side, also). The oxidation half-reaction is: NADH → NAD+ + H+ + 2e-, which is balanced in a similar manner. At this point the half-reactions are added in such a way that the e- involved will cancel. Since two e- are involved in both the oxidation and the reduction, the two half-reactions can be added directly to provide the balanced reaction.

Question 141: Which of the following most likely explains why the bacterial colony did NOT grow immediately after the polysaccharide was added?

The digestive enzymes for the polysaccharide had to be transcribed and translated. the regulation of gene expression is one method by which bacteria respond to changes in their environment, in this case the addition of a new metabolite (polysaccharide). When polysaccharide is absent, the enzymes necessary to digest it are not expressed. However, upon addition of polysaccharide, in order for it to be used as an energy source, expression of the enzymes becomes necessary. Thus, the lag in colony growth represents the period in which the expression of the enzymes is occurring

Question 12: Two additional compounds were studied: NO2(OH) dissolved in water and produced an acidic solution, and Ni(OH)2 dissolved only in an acidic solution. What type of compounds were these? NO2(OH) was an oxyacid and Ni(OH)2 was a base.

The first substance is nitric acid, HNO3. Since this substance dissolves to generate an acidic solution, the bond between O and H in the structural formula NO2OH breaks when the substance dissolves, making it an oxyacid. The latter substance, Ni(OH)2, is apparently insoluble in neutral water, but will dissolve if the solution is acidic. This behavior is typical of substances that feature basic anions. The bond between Ni and O is the one that breaks when Ni(OH)2 dissolves. The hydroxide ion that is produced quickly reacts with protons in solution and cannot react again with Ni2+ to form a precipitate.

An ultrasound examination could show the motion of a fetus. In order to image this motion, the ultrasound examination devices requires what minimal information?

The speed of the sound, and the frequencies of the sound waves emitted and observed. the Doppler effect is used with ultrasound waves to provide fetal images. The Doppler effect relates the frequency of the ultrasound wave as detected by a moving detector to the frequency of the wave when the source is stationary, the speed of the source, and the speed of the detector. Three of the four quantities involved in the effect are required.

What information about an axon is required to calculate the current associated with an NCV pulse

This is a question about Ohm's Law, I = V/R. To determine R, the resistance per unit length, the length, and the potential V are needed

The genes for red-green color blindness will affect production of proteins in which of the following types of cells?

Visual receptor cells in the retina photoreceptors, which are visual receptor cells in the retina, absorb light.

The overall reaction scheme for enzymes of the CYP450 enzyme family is shown with R representing the substrate. NADPH + H+ + O2 + R-H → NADP+ + H2O + R-OH In this reaction, NADPH functions as:

a reducing agent. NADPH is acting as a hydride transfer agent which reduces oxygen.

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

according to Archimedes' Principle, the ratio of the density of an object to the density of the fluid it is submersed in is equal to the ratio of the weight of the object in air to the difference of submersed weight and weight in air.

Passage: The 99Mo decays to 99mTc, releasing a beta particle β- and an antineutrino ῡ. The electrically charged particle emitted during the decay of 99Mo is:

an electron the negative beta particle is the name given to the electron emitted during the nuclear decay of a heavy nucleus.

What type of reaction is Reaction 1? 2HCl(aq) + Mg(s) → MgCl2(aq) + H2(g)

atoms involved in Reaction 1 change oxidation states during the reaction. For instance, Mg changes from an oxidation state of 0 to +2 in converting from elemental Mg to MgCl2.

A separate group of scientists repeated the amino acid transport experiments described in the passage. All protocols were performed as outlined in the initial study with one major exception: D-alanine was used as the primary amino acid substrate. What effect will this change have on the synthesis of new proteins in the animals studied? Protein synthesis will:

be inhibited The answer to this question is D because only L isomers are used to form proteins during ribosomal protein synthesis.

IR spectrum range 1580-1610 cm-1 this is for what

conjugated or aromatic C=C bond

Myopia is a condition of the eye where the crystalline lens focuses the light rays to a position between the lens and the retina. To correct for this condition, a thin lens is placed in front of the eye that will help to focus light on the retina. The type of lens required is:

diverging lens a diverging lens will spread out the light before it reaches the lens of the eye which will cause light to focus on a point closer to the retina.

Question #41: What factor explains how a single stereoisomer is formed in Reaction 2?

enzyme is chiral answer to this question is D since it is the only possible explanation for the observed stereospecificity of the reaction. Neither reactant is chiral, but a chiral product forms because the catalyst (the enzyme) is chiral.

What is the net charge of both pantothenate and phosphopantothenate in aqueous solution at pH 7?

in water at pH 7, the carboxylic acid of pantothenate will lose a hydrogen ion to become a carboxylate (−1) for a net charge of −1 on pantothenate. The phosphate group of phosphopantothenate will lose two hydrogen ions (−2) and the carboxylic acid will lose one hydrogen ion (−1) for a net charge of −3 on the phosphopantothenate.

One function of the myelin sheath is to:

insulate the axon from the surroundings. The purpose of myelin sheath is to assist with the propagation of nerve impulses. It functions in this capacity by insulating the internal cytosol from the extracellular fluid. When the nodes of Ranvier open in response to stimulus, the resulting depolarization can only be transmitted along the axon since the myelin sheath is insulating.

Suppose that at the end of Reaction 1 the level of the aqueous solution were 26 cm higher inside the buret than outside. Compared to ambient pressure, the pressure of the gas inside the buret would be:

lower the level of the liquid inside is higher than outside which results from the fact that the air pressure outside is higher than the pressure inside. Pressure builds on the inside by raising the liquid level. When the sum of the inside air pressure plus liquid pressure equals the outside air pressure, the liquid level stops rising (attains equilibrium).

By allowing STx to move from the early endosome to the Golgi, subunit B permits the toxin to bypass which organelle?

lysosome

If the concentration of amino acid transport protein is increased, the transport affinity Kt of L-alanine will:

not change transport affinity for a given substrate (in this case, alanine) is a property of the amino acid transport protein itself, and thus, Kt will not change as a result of there being more transport protein. In other words, the Kt value is not dependent on the concentration of the amino acid transport protein.

refers to the perpetuation of inequalities through social institutions (such as education or the economy)

social reproduction

What is the net charge of the peptide Arg-Ala-Phe-Leu at pH 8?

the net charge is equal to the sum of all charged portions of the peptide. The N-terminus contributes a +1 charge along with the Arg side chain. The C-terminus contributes a -1 charge, so the net charge is +1.

The individual cells making up a tissue differ from single-celled organisms such as Paramecium in that only the latter: are capable of extended independent life.

tissue cells divide by mitosis, contain subcellular organelles, and can metabolize nutrient molecules, but are not capable of extended independent life.

If a cerebral malaria-causing infected erythrocyte, as described in the passage, lost its adhesion to endothelium, it would most likely first flow into which type of blood vessels?

veins The answer to this question is B because veins are the first vessel type downstream of venules. According to the passage, binding of infected erythrocytes to brain venule endothelium causes cerebral malaria.

The hydrogen ion concentration of the unknown aqueous solution was 1 × 10^-5 M. The unknown compound was probably a:

weak acid because the hydrogen ion concentration for this solution is greater than 1 × 10-7 but much less than the concentration of the unknown compound itself. This means that the compound only partially ionized to form hydrogen ions. This is behavior that defines a weak acid.