Bio, Math, and Organic Question

LonleySol, I think you're right on the OChem question. It meets all criteria except Huckel's rule which, by definintion, makes it anti-aromatic and very unstable: cyclic, conjugated, planar. I think it should be anti-aromatic.

Lonely Sol said:

Bio Question:

1. How many turns does the DNA make around each histone?
--I know its either 2.5 or 1.5 but one question I had said it was 2.5 and another said 1.5. Does anyone know which one?

2. If Large intestine is removing excess salt from your system, is it an excretory system?
-The kaplan notecards say yes but the schaums book is saying large intestine is not an excretory organ?

3. What is the difference between catalyst and enzyme? And are all enzyme catalysts and vice versa?

MATH Question:

1. you have 3 points with cordinates A =(3,-6), B=(1,1), and C=(7,6). What is the area of the triangle ABC?


Organic Question:

1. Is cyclooctane with 4 double bonds an anti-aromatic or non-aromatic
--I always thought it was anti since it meets huckel's rule but the Topscore T-2, there is a wuestion which says it is not.

*Sorry for posting all questions in one, just didn't want to waste wall space!
*Also, just want to thank you for all your help!

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you should look at this way if there are 2 electrons in each orbital then is non aromatic. if one electron in orbital then is anti-aromatic

Here's a question for you...What's the difference between an enzyme and a hormone?

REH said:

Here's a question for you...What's the difference between an enzyme and a hormone?

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Hormone is a substance which is generally released in small amounts directly into the bloodstream and travels to distant organs to perform their functions.

Enzyme is a protein which catalyzes a reaction in the body. There are many ways an enzyme can reduce the activation energy of any given reaction.

MATH: 1. you have 3 points with cordinates A =(3,-6), B=(1,1), and C=(7,6). What is the area of the triangle ABC?

There's probably a simpler way but here's what I did... I know how to find the area of a parallelogram using determinants. But you need one of the three coordinates to be (0, 0). You can do this by subtracting one of the coordinates from all 3 of them:

Let's choose (1, 1). We want to relocate that to (0, 0). So we subtract 1 from the x and 1 from the y - from EACH coordinate. Now we have: A = (2, -7) B = (0, 0) C = (6, 5). So since we have one of our coordinates as the origin, we essentially have two vectors - [2, -7] and [6, 5]. If we find the magnitude of their determinant, we have the area of the parallelogram they form. If we divide that by 2, we'll have the area of the triangle:

Determinant: If you have a 2x2 matrix [a, b] (row 1) and [c, d] (row 2), the determinant = ad - bc. We put one set of coordinates on row 1 and the other on row 2. So row 1 = [2, -7] and row 2 = [6, 5]. The determinant is 2*5 - (-7*6) = 10 + 42 = 52. Divide that by 2 and you get Area = 26.

Again, this is complicated and I'm sure there's other ways to figure it out. But that's what I thought of first. This wasn't exactly an easy problem to graph and figure out the answer to.

Edit: I spent about 15 minutes solving it based on coordinates alone. I used one of the sides as the base, figured out the slope, figured out the slope of the perpendicular line to it, figured out the equation of the line leading up to the third vertex with that slope, then figured out the x and y coordinates where the 'height line' met the 'base line'. I found the distance of the height and the distance of the base, did 1/2 b * h, and got 26. The answer is correct.

REH said:

Here's a question for you...What's the difference between an enzyme and a hormone?

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ANS: You can't hear an enzyme. lol!

BodybldgDoc said:

math
Use the distance formula to find the sides of the triangle ABC
so between co ordinates A(3,6) and B(1,1)
d=sq rt (x2-x1)^2 + (y2-y1)^2
=sq rt (1-3)^2 + (1-(-6))^2
=sq rt 4 + 49
= sq rt 53 = 7.3 so side AB=7.3

same thing for side BC, by using the distance formula we get side BC
as 7.8 <--- base of triangle
then to find the height of the triangle AD we use the pythagorean formula
AB^2=BD^2 + AD^2
7.3^2 = 3.9^2 + AD^2
AD^2=7.3^2-3.9^2
AD=6.1 <-- height

Finally Area of triangle is 1/2 * base * height
so we have 1/2 * 7.8 * 6.1= 23.79

Someone please correct me if I'm wrong.

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Are calculators allowed in the DAT? if no... there is no way in hell i would do all that math for that one problem.. ^_^.. (not in my head at least... and not for my small head anyways)

Lonely Sol said:

Hey, thanks for all you answers for bio and stuff, but was just wondering how do you know which one is a base, and which one is the height, since it doesnt say it is a right triangle or anything?

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Okay even though I edited mine like 50 billion times, the answer is still 26. It's easier to work with determinants.

This is NOT a right triangle. You can arbitrarily choose any side to be a base or a height, but then you have to find the other one correctly. Look at my post above.

Doubtful.

If I am remembering this correctly, cyclo-octane with alternating double bonds is NOT anti aromatic. It is non aromatic because it is not planar. If its natural conformation were planar, it would have been anti.

Cyclooctane is non-aromatic because it is nonplanar. It can be viewed as the Tub conformer, which is non-planar.