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Originally posted by Tweetie_bird:
•I bet you mine was lower!

And the wager starts at 19...anybody lower than a 19? going once...going twice....anybody?•••
Yes, I have 17 on my diagnostic. and I took mcat in august and I will be retaking it this april.
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Question: What is the general consensus about Columbia Review MCAT Practice Exams? I have been taking these for the past two weeks and scoring well. I could use some feedback on what people think about them. Thanks.

Dr. J?
 
ok, time out session you guys....
I wanted to just give y'all some luvin and tell you that I am really REALLY proud of us. :clap: :clap: :clap:
I love your spirit, guys!!! This board is doing awesome, post some more tricky questions....and let's get this bitch on the road! :eek:
Pardon mi langue. :D :D
Tweetie
 
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Originally posted by Dr. J?:
•Question: What is the general consensus about Columbia Review MCAT Practice Exams? I have been taking these for the past two weeks and scoring well. I could use some feedback on what people think about them. Thanks.

Dr. J?•••

Lately, Columbia Review stuff has been given the thumbs down b/c of errors in its books that are sold in stores. I've done those exams and I've also done the materials that are the home study version, where they are ordered DIRECTLY from the CA home-base (they also give courses just like KAPLaN, PR, and Examkrackers) and they're not too bad (Notice I didn't say they were perfect then again, what is). About the errors in columbia reviews stuff, that's true but then again, I have found errors (approx. 13 so far) in Princeton Review material that you get with the course. For KAPLAN, I don't how many of you know this, but my girlfriend took the exact same diag. BACK IN 1996!!!! (I can prove it b/c she still has a copy of her diag exam from 1996) So are they really up to date? All in all, no amount of prep material will give you the actually feel of the MCAT until you actual take the real one. I mean 100% feel. The reason that we're all going out and buying these materials is to prepare us the best that we can so that we're ready but, in the same process, we're going crazy b/c we also feel we're not being prepared enough even after going 50 or so practice exams. No prep material is perfect in it's presentation and feel for the real thing. So just keep working on many practice exams and understand why you got the questions wrong instead of going crazy about going from a 37 to a 31. If you suspect errors, take the question to a professor and work it out with him or her, this may feel time-consuming, but it actually helps you retain the information by understanding as oppose to memorization (spelled incorrectly). I know med school is competive but the last thing you need is worry about is what you got on these practice exam and just concentrate on doing the best you can. In the end, it'll all work out. About the Columbia review material that can be brought in stores, I did low 30's, but i'm not going to go crazy about it.
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Thanks for the Kaplan info!

Ok, here's the question of the day.

But guys, please EVERYONE post a question each day. Just as you come across a good question type it up for the rest of us. I think it will help everyone, including you. I find that when typing these questions I remember the answer better :)

Ok, so here it is
When nucleophilic substitution occurs at a carbonyl, the weakest base is usually the best leaving group. what is the order of reactivity in a nucleophilic substitution reaction from most reactive to least reactive for the following compounds?
acid chloride
ester
amide


and the answer is:

acid chloride, ester, amide
 
yayyy! I knew this one.
I got one for you, don't have it off hand but the gist is in here. Which organelles are not membrane bound?

1. Golgi
2. Smooth ER
3. Nucleus
4. Ribosomes.

Kinda tricky, but with some basic info you can get it right.
And the answer is....

Ribosomes.
 
Since when was a ribosome an organelle?
 
Yay Tweetie! Thank you! I got that right. We're a combined 2 for 2 today.

Here's another one for you

Tolunene rects with nitric acid to form ortho, para, and meta. If the position of substitution were chosen at random, what would be the expected percentage of m-nitrotoluene from the reaction?


and the answer is...


40%: 2 meta locations possible out of 5 total (2 ortho + 1 para + 2 meta)
 
oh that was a teaser!
I consider ribosomes to be organelles...don't you?? Am I missing something?

I am confused on a certain concept--the difference b/w "amnion".."yolk sac"..."..."allantois" and "chorion." I know what each one is, but I don't undertand how the placenta arises from these 4 structures. Anybody?

Tweets
 
Hey Tweetie,
My anatomy and physiology book states that ribosomes are organelles. As for the last question, I can't help you there I am a chem. major (I don't remember my anat & phys or bio enough to explain that one :) ). Good luck with your studying! :D
 
Originally posted by Premed315U:
•Yay Tweetie! Thank you! I got that right. We're a combined 2 for 2 today.

Here's another one for you

Tolunene rects with nitric acid to form ortho, para, and meta. If the position of substitution were chosen at random, what would be the expected percentage of m-nitrotoluene from the reaction?


and the answer is...


40%: 2 meta locations possible out of 5 total (2 ortho + 1 para + 2 meta)•••

This is incorrect :) Toluene is an Ortho Para director (With para being the preferred product) The actual % would be something like 60 % Para, 29% Ortho, and 1 % Meta. (The reason is because benzene is highly resonated, and whith an OP director the meta attack can't have an octet- which is bad!)

Good luck everyone!

Kirk
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Originally posted by Kirk:
•

This is incorrect :) Toluene is an Ortho Para director (With para being the preferred product) The actual % would be something like 60 % Para, 29% Ortho, and 1 % Meta. (The reason is because benzene is highly resonated, and whith an OP director the meta attack can't have an octet- which is bad!)

Good luck everyone!

Kirk•••
Ouch, after reading your post I was reminded of how much of my organic chemistry that I have forgotten (especially after having read the other post and not having picked up on the answer being wrong). But, I went back to my orgo book and refreshed my memory. Which leads me to why I am posting again. The answer is wrong but b/c of carbocation stabilities; meta give 2 carboc. and ortho and para give 3 carboc. And a 3 carbo. is a happy carboc. Now, I know I will once again forget this and have to restudy this if I have to take the MCAT again :eek: :eek:
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Thanks so much every9one.
Another mistake in a prep book :( <img src="graemlins/pity.gif" border="0" alt="[Pity]" />

Hey everyone please post some questions of the day :clap:
 
Which of the following events does NOT play a role in the life cycle of a typical retrovirus?

A. Viral DNA is injected into the host cell.
B. Viral DNA is integrated into the host genome.
C. The gene for reverse transcriptase is transcribed and the mRNA is translated inside the host cell.
D. Viral DMA incorporated into the host genome may be replicated along with the host DNA.

NOTE: I'll post the answer later today.
:cool: :cool: :cool:
 
Originally posted by Premed315U:
•Thanks so much every9one.
Another mistake in a prep book :( <img src="graemlins/pity.gif" border="0" alt="[Pity]" />

Hey everyone please post some questions of the day :clap: •••

Premed,

I don't think it was a mistake. The question asked what would be the % of m-substituted if the substitutions were chosen at "random". They probably didn't want you to consider the electronic effects, just the ratio.
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A. Because viral RNA is injected.?

Oh, ok so 40% would be right then. Oh good, I'm glad :)

Thanks everyone!

I'll post some questions later. I'm going to do a full length today so I should find a few to post for everyone as I'm doing the test.

Good luck everyone.
 
Prior to infecting a bacterium, a bacteriphage must:
A. reproduce, making copies of the phage chromosome.
B. intergrate its genome into the bacterial chroomosome.
C. penetrate the bacterial cell wal completely.
D. attach to a receptor on the bacterial cell membrane.
NOTE: Answer later today. :p :p :p :p :p
 
i believe reverse transcriptase is already in the virus... so no need to transcribe it, at least initially. and i'm not sure about "DMA" :)

edit: ok i got that totally reversed. that's ok, i haven't reviewed bio yet hehehe

edit2: Jeebus! I overlooked the easiest answer by far hahaha. Answer is A.
 
I'm a biochem grad student and to call ribosomes organelles is a bit outragous. (I'm mad at the textbooks, not you guys) Ribosomes are RNA/protien enzymes, and in no way should be considered organelles. It's just a very complex protien. Organelles are millions of times bigger than ribosomes.
 
Originally posted by daisygirl:
•Hey Tweetie,
My anatomy and physiology book states that ribosomes are organelles. As for the last question, I can't help you there I am a chem. major (I don't remember my anat & phys or bio enough to explain that one :) ). Good luck with your studying! :D •••

Thank Daisy! I was a bit thrown off too when saw that question, but it's nice to have it be cleared off. Anybody with the other question i asked? I am confused about the whole fetal circulation thing. :mad: :mad:

Tweetie
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Here's a great question.

Within the cell, protein turnover reflects a balance between the rates of protein synthesis and degradation. for a given protein the rate of synthesis is regulated by which of the following factors?

a) the amount of DNA available for transcription
b) the amount of RNA available for translation
c) the # of ribosomes available for protein synthesis
d) the # of tRNA molecules available for transport of amino acids


and the answer is...


b :clap:
 
Ok, I got the answer right but I would like to know why C and D are wrong. Anybody??

And don't avoid my questions this time!!!

Tweetie
 
Tweetie, because regulation of protein synthesis lies at the level of mRNA molecules.
 
Originally posted by Sm00th13:
•Which of the following events does NOT play a role in the life cycle of a typical retrovirus?

A. Viral DNA is injected into the host cell.
B. Viral DNA is integrated into the host genome.
C. The gene for reverse transcriptase is transcribed and the mRNA is translated inside the host cell.
D. Viral DMA incorporated into the host genome may be replicated along with the host DNA.

NOTE: I'll post the answer later today.
:cool: :cool: :cool: •••

The answer's "A".
Click to expand...
 
Originally posted by Sm00th13:
•Prior to infecting a bacterium, a bacteriphage must:
A. reproduce, making copies of the phage chromosome.
B. intergrate its genome into the bacterial chroomosome.
C. penetrate the bacterial cell wal completely.
D. attach to a receptor on the bacterial cell membrane.
NOTE: Answer later today. :p :p :p :p :p •••

The answer's "D". Good Luck!!!
Click to expand...
 
Originally posted by Sm00th13:
•

The answer's "A".•••

:mad: :mad: :mad: I got that one wrong.
Can somebody please tell me why A is NOT a part of the damn lifecycle of a @#$@# retrovirus??? Doesn't the DNA have to be incorporated into the cell first? :rolleyes: :rolleyes:

I haven't done viruses yet, although I feel like my BRAIN might have one!
Tweetie
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Tweetie, retroviruses mean RNA Thing RNAetrovirus :clap:

Come one everyone, post your question of the day.
 
Originally posted by Tweetie_bird:
•

:mad: :mad: :mad: I got that one wrong.
Can somebody please tell me why A is NOT a part of the damn lifecycle of a @#$@# retrovirus??? Doesn't the DNA have to be incorporated into the cell first? :rolleyes: :rolleyes:

I haven't done viruses yet, although I feel like my BRAIN might have one!
Tweetie•••

you have look at it PRIOR to infecting NOT after the nuclei acid has entered. There's a distinction between "injection" and "intergration" as in the case with bactiophages which "injects" it contents THROUGH the cell wall. At that point, it could go into lytic stage or lysogenic stage, at which it could then be "intergrated". With retroviruses, (e.g. HIV virus) they enter the mammalian cells by endocytosis (Notice there is no injection of their contents). Once in the cell, it's RNA is transcript to DNA and incorperated into the host genome. This question was a bit subtle.

Here's a question till next week: Why do antibodies have a hard time detecting viruses (especially HIV) after being exposed to it for a while at the molecular level? Think about the DNA-&gt;RNA-&gt;protein dogma.
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Ever get the feeling we're all a bunch of dorks?

Oh well, such is life.

Question of the day:

(for all you physics lovers out there...)

An object is dropped from a height of 980m. Let T be the time requied to fall the entire distance and let "t" be the time required to fall the first half of the distance. Calculate the ratio T/t. (ignore air resistance)

a. 1/2
b. 2^1/2
c. 2
d. 4

And the answer is....

B.


It's written as the square root of 2 in the book, but I don't have a square root key on the computer.

I haaaaaaate physics!

<img src="graemlins/pissy.gif" border="0" alt="[Pissy]" />
 
Hey guys,

I was wondering...Does anyone have experience with making webpages or working with online communities through MSN or yahoo? I was thinking it would be kinda cool to make a site or community for the mcat stuff where people could post questions and answers and do other stuff. There could be folders for each day or by topic (bio, chem.etc).

Just a thought. I like this thread!
 
oooooo smoothie! you're a smartie pants! it makes more sense now. Thanks!

I don't have a question, but I do have some summary to share..about BONES!

So, two kinds of bone--spongy and compact. Compact bones make up long limbs. What are they composed of? Collagen and Glycoproteins (organic stuff) and Calcium, phosphate, hydroxide ions (that form Hydoxyapetite crystals) and also Na, K, and Mg.

How do you recognize spongy bone?
Well, it has little trabeculae (which are like little spicules) with spaces in between where marrow is made.

How do you recognize compct bone?
yeap, you got it! Osteons! Osteons are units of compact bone. Basically,
1 Osteon = one long canal (Haversian canal) that is surrounded by Lamellae. You can also recognize compact bone by just looking at it's matrix and seeing these concentric circles (lamellae layers around H. Canal.)

Kapish?
:clap: :clap: Tweetie :clap: :clap:
 
Smoothie, in response to your question, that IS how resistance is conferred upon virus, right?

So, I am assuming that this is how it works. Virus A goes into body, Antibody A recognizes it, kills it. Over time, the virus, can back-mutate and transcribe and translate different combinations of it's gene (?) that codes for the specific receptor the Antibody A attaches to. Now, since the virus is wearing a cute new little dress, antibody A doesn't recognize it..and BOOM! You got resistance!

I hope that's right. :rolleyes:
Tweetie
 
Since I'm again studying for the MCAT (2nd time around) I thought I'd join in with the question fun. Here's a g-chem (easy) question:

Which of the following elements has the GREATEST ionization energy?

a. S
b. Ag
c. Al
d. Fe


And the answer is.....
a.
Why?
First off, I thought about the periodic trends and which of the elements is the closest to having their fullest octect. Sulfur only needs 2 more electrons to be "happy", whereas the others are crazy transistion metals that don't mind having their electrons come and go.
But, if you want a more "chemical" reasoning to why (a) was the choice is because....
The greatest ionization energy is associated with the compound that is hardest to ionize. Only sulfur is a non-metal, and non-metals have higher oxidation energies than metals. With that said, metals are easier to oxidize (lose electrons) more readily than non-metals. And non-metals do NOT oxidize as readily. Therefore, they'll want to keep all of their electrons.
:p
 
Showee, that's such a great idea.

I don't know how to do a webpage for questions by day. I hope someone else knows how to do it though
 
hey guys i'm setting up a webpage to have question/answers. i'm going to put up easy intructions so that we can all post questions and answers.
 
Website is up!
It'd be cool to have many people upload questions and answers so that I don't have to do it like everyday!
Message me for the password. Give it out to anyone willing to contribute.
login: mcat4_02

<a href="http://www.geocities.com/mcat4_02/" target="_blank">http://www.geocities.com/mcat4_02/</a>
 
also wanted to add that more experienced web dudes are welcome to use a different format from the tutorial i put up.
:D :cool: :rolleyes: :) <img src="graemlins/lovey.gif" border="0" alt="[Lovey]" /> <img src="graemlins/laughy.gif" border="0" alt="[Laughy]" />
 
oh my lord...ok, even though the website looks GREAT schoolboy, I am not sure if I am computer literate enough to do it each time, plus, it seems to take more time to do that, than to just post here.

I will surely check out the website and see what y'all wrote...however, I think I will post my questions on this page, if it's alright with y'all. Maybe when I have more time I'll learn how to do that stuff..just not yet. Sorry!

Tweets
 
well, we'll just see if the website is worth the trouble, if not we can always post here :cool:
also, i don't want to give the impression that everyone should post... only those few that want to, or are comfortable with the web stuff. i use MS frontpage so it's ridiculous easy to do :D
 
Schoolboy, wow!!! That looks great.

I'm not sure exactly how to do the posting either.

Do you think that maybe people who are computer illiterate can post their questions here and then you could transfer it daily to the website? Hopefully that will just include Tweetie and I :)
 
i think it'd be best if i just post them if it's too much trouble for you guys. it's really easy for me using my html program. not a big deal...
 
Originally posted by Tweetie_bird:
•Smoothie, in response to your question, that IS how resistance is conferred upon virus, right?

So, I am assuming that this is how it works. Virus A goes into body, Antibody A recognizes it, kills it. Over time, the virus, can back-mutate and transcribe and translate different combinations of it's gene (?) that codes for the specific receptor the Antibody A attaches to. Now, since the virus is wearing a cute new little dress, antibody A doesn't recognize it..and BOOM! You got resistance!

I hope that's right. :rolleyes:
Tweetie•••

your kind of there.
First of all, what do antibody recognize?
they recognize proteins or better yet,epitopes (spell incorrectlY) Using HIV as ex., they have spike proteins which are used for ligand-receptors interactions. NOw while virus are being replicated and translated, there is a proofreading ability in DNA polermase, but is there proofreading ability in RNA polermase? NO. This allows errors to go unnotice, so when genes for spike protein (that eventually be on the lipid membrane of the HIV virus) are translated incorrectly, this is where problems arises. YOur immune goes a primary response and a secondary response. The primary response takes more time than a secondary response, so the virus uses that it's advantage while it's tons of virions produced, which each may have different mutations, and population growth is rapid, the immune system can't respond quickly enough to the various different epitopes that are being produced.
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Schoolboy, thank you so much for posting it for us. That's so nice of your. This is going to be the greatest resource!!
 
Ok, here' s the question of the day.

Which organ is involved in regulation of all of the following; ac-dbase balance, blood pressure, water balance, and removal of nitrogenous wastes?

a) liver
b) spleen
c) kidney
d) large intestine

and the answer is...

kidney
 
How do you guys figure out your score for AAMC I? It doesn't really have a score conversion, just a showing of percentages.

Thanks!
 
Here's another question of the day.

The sodium pump would be most active in cells of which of the following structures?
a) veins
b) loop of Henle
c) lungs
d) bone marrow

and the answer is..

b, however, I don't understand why. Does anyone know?
Thanks!
 
The ascending loop of Henle is the site of lots of active transport (Cl- out, Na+ passively diffusing... so says TPR book). I don't think the other structures deal with Na+. Veins don't transport stuff, lungs are about oxygen, and I have no idea what bone marrow does. :p
 
What about the descending loop of henle? Which does more active transport ascending/descending? (Don't have practice books on hand)
 
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