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MCAT integrated > MCAT CHEM/ Phys > Flashcards

MCAT CHEM/ Phys Flashcards

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MCAT flashcards
1
Q

Pulmonary surfactant is a naturally occurring lipoprotein that greatly reduces the coefficient of surface tension of the pulmonary fluid. Synthetic versions of pulmonary surfactants are often given neonatally to treat respiratory distress syndrome. Which of the following best explains this treatment?
A. Decreasing the surface tension coefficient decreases the amount of fluid in the lungs.
B. Decreasing the surface tension of pulmonary fluid allows the wet alveoli to expand more easily during respiration.
C. Decreasing the surface tension of pulmonary fluid increases the force that holds the alveoli open during respiration.
D. Decreasing the surface tension of pulmonary fluid increases blood flow and decreases the probability of blood clots.

A

B. Decreasing the surface tension of pulmonary fluid allows the wet alveoli to expand more easily during respiration. Correct Answer

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2
Q

The correct SI unit of denstity of water is

A

ρ = 1000 kg/m3”.

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3
Q

Increasing temperature does what to the solubility of gases in liquids.

A

decreases

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4
Q

Which of the following is correct regarding the indicated biochemical pathway and its products?

  1. The Krebs cycle produces NADH and FADH2 following oxidation of acetyl-CoA carbons.
  2. Beta-oxidation produces NADH and acetyl-CoA following oxidation of acyl-CoA.
3. The electron transport chain produces NADH and ATP following oxidation of electron carriers.
    A. 	I only
    B. 	I and II only Correct Answer
    C. 	II and III only
    D. 	I, II, and III Your Answer
A

I and II only Correct Answer

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5
Q

A person on a sled is moving to the right along a horizontal frictionless surface. The person throws a ball straight upward (as seen in the person’s frame of reference). What will happen to the motion of the person and sled?

A. 	They will slow down.
B. 	They will speed up.
C. 	They will speed up at first and then slow to their original speed when the ball lands. 
D. 	They will stay at their original speed. C
A

D. Newton’s Third Law (or conservation of momentum) provides the solution. Before the throw, the person, sled, and ball all have horizontal velocity. When the person throws the ball upward in her reference frame, she exerts an upward force on the ball. Therefore a downward reaction force is exerted on her by the ball. This downward force cannot provide an acceleration in a horizontal direction (and indeed, it doesn’t provide an acceleration in the vertical direction either because of the normal force from the ground on the sled), so there is no change in horizontal velocity or speed.

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6
Q

A medium with index of refraction n is surrounded by air. The critical angle inside of the medium is then determined. The medium is then submerged in a fluid with index of refraction nfluid. If 1

A

The correct answer is choice B. Total internal reflection can only happen when the incident medium has a greater index of refraction than the surrounding medium. Since the original medium has a greater index of refraction than the fluid, it must still be the incident medium. This eliminates choices C and D. Snell’s law of refraction states that n1sinθ1 = n2sinθ2. For total internal reflection, θ1 = θcritical and θ2 = 90°, which means that n1sinθcritical = n2. The index of refraction of air (n2 in this case) is 1, so immersing the medium in fluid has caused n2 to increase. Since n1 remains constant, the equation tells us that sinθcritical, and therefore θcritical itself, must increase.

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7
Q

The conjugate acid of a weak base will do what to a solution/s pH??

A

will lower the pH

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8
Q

the conjugate base of a weak acid will do what to pH

A

raise it

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9
Q

The weight of an object (i.e., the force of gravity) on the surface of a planet or moon is

A

w = GMm / R^2, where m is the mass of the object, M is the mass of the planet or moon and R is the radius of the planet or moon.

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10
Q

what happens in Beta - decay?

A

In beta decay, an unstable nucleus with too many neutrons attempts to become more stable by converting a neutron to a proton and emitting an electron. The atomic mass stays the same. Thus the atomic number (number of protons) increases by one (eliminate choices A and C) and the number of neutrons decreases by one (eliminate choice D; choice B is correct).

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11
Q

Km tells us

A

the concentration of cation necessary to reach 1/2 Vmax

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12
Q

Amiloride serves as a competitive inhibitor for lithium transport by the Na+/H+ transporter and will therefore have what impact on maximum transport

A

no impact on the maximal rate of transport

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13
Q

relate standard reduction potentials (E°) and standard free energy

A

ΔG° = –nFE°

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14
Q

how is Euchromatin organized relative to heterochromatin?

A

Euchromatin is loosely condensed to allow high transcriptional activity

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15
Q

DNA ligase functions by

A
  • catalyzing phosphodiester bond formation between the ends of two strands of DNA
  • The Okazaki fragments produced during DNA replication must be joined by DNA ligase with the formation of a phosphodiester bond
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16
Q

The relation between photon energy and wavelength is given by

A

E = hc / λ

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17
Q

hydrogen bonding does what to melting points, boiling points, and solubility in water?

A

hydrogen bonding increases all

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18
Q

mesylate

A

a compound containing the functional group, -SO3CH3

  • prepared by mixing methylsulfonyl chloride and an alcohol in the presence of a base
  • *good leaving group and protects from oxidation
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19
Q

tosylate

A
  • S03C6H4CH3
  • produced by adding an alcohol to p-toluenesulfonic acid
  • *good leaving group and protects from oxidation
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20
Q

how can I protect alcohols from being reduced by LiAlH4??

A

add a diol to make a ketal or acetal

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21
Q

whats a hydroquinone

A

benzene ring with 2 hydroxyl groups

22
Q

whats a hydroxyquinone

A

contains two carbonyls and variable number of hydroxyl groups

23
Q

coenzyme Q

A
  • ubiquinone

- vital electron carrier in Complexes 1,2,and 3 of electron transport chain

24
Q

IMINE

A

a compound with a nitrogen atom double bonded to a carbon atom

25
Q

what functional group corresponds to a chemical shift of 10.5-12?

A

Carboxylic acids

26
Q

what functional group corresponds to a chemical shift of 9-10?

A

Aldehyde

27
Q

what functional group corresponds to a chemical shift of 6-8.5?

A

aromatics

28
Q

what functional group corresponds to a chemical shift of 4.6-6

A

alkenes

29
Q

name the 3 intermolecular forces that affect solubility

A
  • hydrogen bonding
  • dipole-dipole
  • Van Der Waals
30
Q

In thin layer chromatography what does a high Rf indicate about the compound?

A

high Rf indicates a non-polar substance

31
Q

whats the equation for lens Power?

A

P=1/f

32
Q

whats the equation for lens

A

1/o + 1/i = 1/f

33
Q

What does PDC convert pyruvate into?

A

The PDC normally converts pyruvate into acetyl-CoA, releasing CO2 and generating NADH in the process

34
Q

Light from visible lasers can heat tissue by:
A. transferring energy at refractive boundaries.
B. being absorbed by chromophores.
C. causing friction with the oscillations of light waves.
D. stimulating radioactive emission.

A

B.
Some molecules such as melanin and hemoglobin act as chromophores, absorbing photons in a wavelength-specific manner and transforming their energy into heat or other forms.

35
Q

The equation for capacitance is :

A 
C = κε0A / d,
K= dielectric constant
36
Q

equations for the potential energy of a capacitor

A

The potential energy stored in a capacitor can be written as (1/2)CV2 or Q2 / 2C.

37
Q

ELectric FOrce equals

A

qE

38
Q

The volume of a gas is defined as

A

the free space within the vessel.

39
Q

The volume of a real gas is always smaller than that of an ideal gas because

A

-the volume of real gas particles is significant and reduces the free space in the vessel.

40
Q

Eukaryotes possess 60S and 40S ribosomes

A

TRUE

41
Q

Which is true of tRNA and translation?
A. Aminoacyl-tRNA synthetase binds an amino acid to tRNA in an ATP-independent reaction.
B. All tRNAs, regardless of the amino acid they can carry, contain a CCA sequence at their 3’ end where they can be bound to an amino acid.
C. Due to the degeneracy of the genetic code, “wobble” codon base pairing can occur in the 2nd position, since only the first and second bases of a codon require accurate base pairing.
D. In eukaryotes, translation involves the 50S and 30S ribosomes.

A

B. B. At the 3’ region of all tRNAs is a CCA (5’ → 3’) sequence to which an amino acid is bound by aminoacyl-tRNA synthetase (choice B is correct). Aminoacyl-tRNA synthetase is responsible for binding an amino acid to tRNA, but does so in an ATP-dependent reaction since the bond formed will contain the energy for peptide bond formation during translation (choice A is wrong).

42
Q

Because of the aforementioned lower importance of resonance in esters, and the greater electronegativity of O as compared to N, the carbonyl carbons of esters are more electrophilic than those of amides.

A

True

43
Q

WHat equation relates pKa to pH?

A

Henderson-Hasselbalch:

pH= pKa + log [ conjugate base/ conjugate acid]

44
Q

disulfide bonds are formed through oxidation of sulfhydryl groups

A

True

45
Q

what equation should be used to calculate the amount of heat required to raise anything to a certain temp?

A

q=mc delta T

46
Q

in gel filtration what elutes first?

A

-bigger molecules will elute first since they wont fit in the beads

47
Q

in purifying hemoglobin from human RBC, a biochemist suspects that some of the molecules have lost their quarternary structure. If she uses gel filtration column to separate the denatured from the non-denatured what would you see?

A

-the non-denatured would elute first since they are bigger and wont get caught in those beads

48
Q

if object distance is greater than the focal distance the object will appear behind the lens

A

TRUE

49
Q

Objects infinitely far away will produce an image the same distance as the focal length far away from the lens

A

TRUE

50
Q

index of refraction

A

n= c/v
c= 3 * 10^8
v= speed of light in new medium
when entering medium with higher index of refraction, light bends toward the normal

MCAT integrated (3 decks)

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