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Quiz thread

Discussion in 'MCAT Discussions' started by Cerberus, Apr 8, 2004.

  1. Cerberus

    Cerberus Heroic Necromancer
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    Answer then ask a question.

    Question 1:

    What type of solvent would be best for favoring Sn1?
     
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  3. LUBDUBB

    LUBDUBB Freakaholic
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    Ok, let's play...

    Polar protic solvents tend to stabilize the carbocation intermediate, increasing the rate of reaction.



    Question 2:

    Which one is more soluble in water, Oxygen or Carbon dioxide, and why?
     
  4. farley is god

    farley is god Empty Tank.
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    polar protic.

    3:

    What's the difference in total ATP production from a molecule of glucose between prokaryotes and eukaryotes?
     
  5. farley is god

    farley is god Empty Tank.
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    edit:

    damn you, LUBDUBB.


    EDIT: NOT SO MUCH EDIT AS NEW POST
     
  6. Cerberus

    Cerberus Heroic Necromancer
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    This is just a guess but I am going to guess that it is CO2 because CO2+H2O <-> H2CO3<->H+ + HCO3-

    A defect in nervous system formation could most likely be attributed to a defect in which germ layer?
     
  7. Cerberus

    Cerberus Heroic Necromancer
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    lets see, 2 net for prokaryotes, 36 for euakryotes?
     
  8. farley is god

    farley is god Empty Tank.
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    the ectoderm gives rise to the nervous system.

    hmm...

    reduction of a ketone to an alcohol will be marked by an appearance of ______ and disappearance of ______ on an IR spectrum.
     
  9. Nuel

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    No difference is expected. Bacterial plasma membrane performs the same function as mitochondria.
     
  10. Nuel

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    dissappearance of carbonyl stretch at approx. 1700cm-1 and and appearance of OH stretch at 3500cm-1. this was too easy. the question on bacterial vs. eukaryotic oxidative respiration was more interesting.
     
  11. Cerberus

    Cerberus Heroic Necromancer
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    Ask your question
     
  12. Nuel

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    In response to cerb:

    What is the sufficient condition for chirality?
     
  13. sdnstud

    sdnstud 1K Member
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    4 different substituents attached to a sp3 atom


    how does an increase in temperature affect the tone played on the piano?
     
  14. Nuel

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    Your answer is wrong. An sp3 chiral center is only a necessary condition for chirality, not sufficient.
     
  15. Nuel

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    Increase in temperature will increase the speed of ambient air, therefore the sound waves will travel faster and the tone would be distorted--as well as the pitch.
     
  16. jhk43

    jhk43 Senior Member
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    thats a cheapie!

    if a fetus lacks just testosterone receptor, but has an XY genotype, what is its internal (m or f or none) and external (m or f or none) genitalia?
     
  17. Nuel

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    It's not a cheapie. Does allene C=C=C have a chiral center? No, but it a chiral molecule. So the sufficient condition is that the molecule not have a mirror plane of symmetry.

    In response to your question, no internal or external genitalia.
     
  18. LUBDUBB

    LUBDUBB Freakaholic
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    36 for eukaryotes, 38 for prokaryotes.

    In Eukaryotes, the two NADH made in glycolysis must be passed across the mitochondrial membrane actively. This yields 2 ATP per NADH for a total of 4 ATP, instead of 3 atp per NADH as is expected of the NADH generated in the mitochondria.

    In prokaryotes, because the two NADH do not have to cross any mitochondrial membrane, they yield 3 atp per NADH.
     
  19. LUBDUBB

    LUBDUBB Freakaholic
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    Well more completely, the oxygen in H20 is slightly nucleophillic so it will attack the carbon on CO2.
     
  20. DrSal

    DrSal Senior Member
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    If the fetus lacks testoesterone receptors it will have female genitalia (external and internal, perhaps underdevelopped) and will be sterile...cuz it'll be almost equivalent to XO and will develop by default as female b/c the testerone isn't sensed.

    Ok, here's a rather lengthy Q ;)

    Who can explain beat frequencies, harmonics and all that jazz?
     
  21. Nuel

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    I knew someone was to comment on this. I wanted to add to this but desisted.

    The eukaryotic yield is theoretically 36 or 38 ATP depending at what level NADH will deliver its electrons on the ETC. Even this is contested among scientists. MCAT won't test this detail.
     
  22. jhk43

    jhk43 Senior Member
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    beat frequency is the numerical difference between any two waves.

    harmonics is the resonance frequency that is characteristic of the system, depending on things like length, wavelength (and indirectly tension, bulk modulus, velocity)



    Consider the rxn between Ester and NaOH. Will the reaction favor nuc. substitution or aldol addition? what about between ketone and NaOH
     
  23. Nuel

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    I erroneously ignored the effect of female hormones. You could be right . . . let jhk confirm.
     
  24. LUBDUBB

    LUBDUBB Freakaholic
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    No testosterone --> no wolffian ducts --> no internal male genitals.

    If the testis still produce MIS, then Mullerian system (internal female genitalia) are also inhibited.

    As for external genitalia, if no testosterone, then xy will develop into incomplete female.

    Hope I'm right.
     
  25. LUBDUBB

    LUBDUBB Freakaholic
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    You are absolutely right.
     
  26. jhk43

    jhk43 Senior Member
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    External Female, No Internal organs.

    Y chromosome-->testicles formed-->MIF and testosterone. MIF prevents female internal organs. No testosterone receptor means no internal or external male organs. However, nothing prevents the default external female genitals from forming.

    well done lubs
     
  27. krull

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    Q: If a rocket take off at an initial velocity of 100 m/s, 75 degrees of the horizontal, and its engine stops working after 11 seconds, what is the maximum height the rocket achieves? (had a similar problem like this on real deal last year :O)
     
  28. Cerberus

    Cerberus Heroic Necromancer
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    My guess is this, in the first 11 seconds the acceration due to gravity can be neglected due to the engine.
    So

    y=11*sin75*100
    y=1062

    then after that point,

    v^2=v^2(initial)+2ad

    0=(sin75*100)^2-2*10*y

    y=466

    So the total distance achieved is

    1062+466 = 1528m
     
  29. krull

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    :clap: :thumbup:

    Here is another one I had.

    What is the length constant found in cells due to a local depolarization?
     
  30. Cerberus

    Cerberus Heroic Necromancer
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    whaaa?
     
  31. jhk43

    jhk43 Senior Member
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    i'll assume sin 75 is given...or you can just figure out that sin 60 = root 3/2 and sin 1 =1--->sin75= ~0.9

    initial vo= 100*sin75 = 90 m/s
    height achieved after 11 seconds: D=RT = 90*11= 990m

    at that point, projectile motion begins
    intial v = 90m/s.
    final v =0.

    Vf^2=Vi^2 +2as

    90^2=0 + 2(10)s
    s=400

    Total distance 990+400 = 1390m
     
  32. krull

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    heh, never heard of the length constant? That's the length a typical conductance length a local response in cells typically has
     
  33. krull

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    yeah u both did it right The numbers will be given

    btw cerb, the answer is (Rm/Rin)^1/2
     
  34. jhk43

    jhk43 Senior Member
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    or u can use a calc :)
     
  35. sdnstud

    sdnstud 1K Member
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    Nope...never heard of it...

    Q: which requires a greater escape velocity (to escape earth)? when rocket is launched at the equator, north pole or somewhere in between?

    This was on the actual mcat i took 2 years back :)
     
  36. jhk43

    jhk43 Senior Member
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    i believe Radius is max at the equator, min at the N pole..

    F=GMm/R^2

    g~M/R^2

    since g~1/R^2, g is max at smaller radius, so escape velocity max @ north pole?
     
  37. jhk43

    jhk43 Senior Member
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    Consider the rxn between an Ester and NaOH. Will the reaction favor nuc. substitution (COOH) or aldol addition/condensation? what about between ketone and NaOH? What about Acid Chloride and NaOH?
     
  38. krull

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    A) nuc sub?

    B) aldol addition

    c) nuc sub

    Q: This was a wierd one I had. Easy but weird. If an object is traveling a 100,000 m/s and it emits a flash of light which travels at a velocity of 186,000 m/s, what is the speed of the particle within the flash of light? (something similar to this)
     
  39. jhk43

    jhk43 Senior Member
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    Relativity??

    NO WAY!
    speed of the particle relative to 186K M/S? i'm assuming its 86k, since relativity aint on the mcat v~[inverse (1+v^2/c^2)]


    back to the ester + NaOH....kinda confused...when do carbonyls prefer substitution, and when do they prefer the alpha hydrogen reactions? I know that alpha hydrogen is increased with withdrawing group, so in these cases it will prefer nucleic substitution.

    the O ester is electron donating, so the alpha hydrogen is less acidic than a ketone rite?


    What is the order of alpha H acidity btw:
    acid chloride, ester, cooh, aldehyde, ketone?
     
  40. LUBDUBB

    LUBDUBB Freakaholic
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    Ester +NaOH is a saponification (base catalyzed hydrolysis)
    R-COOR' + NaOH --> R--0-:Na+

    Acid Chlroide + NaOH will hydrolzye the acid chloride back to the carboxylic acid.

    Ketone + NaOH ...hmmmmm..well adding NaOH to an aldehyde/ketone forms the enolate ion. Now if we've got an aldehyde we can have an aldol condensation. I guess the ketone will also undergo aldol condesation but the eq concentrations will be minimal.
     
  41. dfleis

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    .
     
    #40 dfleis, Apr 8, 2004
    Last edited: Mar 21, 2010
  42. jhk43

    jhk43 Senior Member
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    i'mma sittin next to lubby on d-day. :clap:
     
  43. jhk43

    jhk43 Senior Member
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    NaOH + Aldehyde/Ketone, does it ever form a COOH via substution? or just aldol addition?
     
  44. jhk43

    jhk43 Senior Member
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    E1 vs. Sn1. in which conditions does E1 win? Sn1 win?
     
  45. Persistence101

    Persistence101 Senior Member
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    Aldehydes and Ketones don't undergo nucleophilic substitution, except with amines to form imines.

    Edit: I don't think they would form COOH via substitution because H and R are horrible leaving groups
     
  46. Persistence101

    Persistence101 Senior Member
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    According to EK, elimination occurs when the nucleophile acts like a base. To avoid this, use a less bulky base.
     
  47. Persistence101

    Persistence101 Senior Member
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    Q: What is amperes law?
     
  48. Persistence101

    Persistence101 Senior Member
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    so is this right?
     
  49. nikibean

    nikibean Tip your guide.
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    Ok, here's a rather lengthy Q ;)

    Who can explain beat frequencies, harmonics and all that jazz? [/B][/QUOTE]

    Not lengthy. Okay, beat frequencies are simple. The beat frequency is the difference between two frequencies, ie, 240 Hz and 242 Hz means beat frequency is 2 Hz. Not so tough. It's just periodic loudness variation when two similar pitches are sounded simultaneously. I could do the wave derivation, but it's much easier to just think of it this way. Think of it this way- if you have a tuning fork and clamp it, you decrease the frequency- it goes flat. Why? Because of angular acceleration. The tines are trying to vibrate but you just increased their moment of inertia, so they are now dissonant with another tuning fork of the same original frequency. That dissonance you hear is beating.
    Harmonics:
    initial frequency, with ONE node is referred to as the "fundamental frequency" also known as the first harmonic.
    Simple: When you have an open pipe (antinode-antinode) or you're in the middle of a closed pipe (node-node) then ALL harmonics are allowed. To find the new frequency of the harmonic, just multiply the fundamental frequency by its integer (ie 2nd harmonic = 2 x fundamental frequency). For Node-Antinode conditions, only ODD harmonics are allowed because of boundary conditions. So you multiply by 1, 3, 5, 7 etc.
    I can't explain Jazz. Sorry. :)

    Okay, here's one:

    If you are farsighted then your _____ point is too ______. You fix with a _________ lens.
    If you are nearsighted, your ________point is too _______, and you fix it with a ________ lens.

    Bonus: What is the sign of the power of the lens you use to fix each problem, respectively?
     
  50. jhk43

    jhk43 Senior Member
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    If you are farsighted then your _focal____ point is too _behind the retina_____. You fix with a _converging________ lens.
    If you are nearsighted, your focal point is too in front of retina, and you fix it with a diverging lens.

    converging lenses, f=+, p=+
    diverging, f=-, p=-


    Would a histone protein be acidic or basic?
     
  51. LUBDUBB

    LUBDUBB Freakaholic
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    quote:
    --------------------------------------------------------------------------------
    Originally posted by jhk43
    E1 vs. Sn1. in which conditions does E1 win? Sn1 win?
    --------------------------------------------------------------------------------



    Given a secondary or tertiary compound and a weak nucleophile (weak base),

    E1 favored by high temps and bulky nucleophile.

    A strong base (strong nuc) will force second-order kinetics.
     

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