Pink Poogle Toy Forum

A lipid bilayer is a membrane that is made up of fatty acid molecules. Fat molecules have big globs of carbon polymer at one end, and this little tail at the other. The tail has a negative charge, the glob does not. This is important.

A lipid bilayer is created when two layers of fatty acids are lined up in opposition - tails facing one another in the middle, with fat on the outside. If this lipid bilayer is folded around, to form a spherical structure (fat on the outside of the wall, fat on the inside of the wall, tails between, and a big hollow middle), it's called a "Vesicle," which means container.

Bilayers form every important interior and exterior membrane in a cell. Plant cells have an extra outer wall, but between that wall and the cytoplasm (sometimes called cytosol) is a lipid bilayer, just like every other cell in the world.

3. That lipid wall around the nucleus is what makes eukaryotes so much more flexible. The DNA is protected, allowing it to do things like grow longer. Longer DNA means...

4. They are. They're the classical eukaryote. The Amoeba eats by extending pseudopods (latin for "fake feet") out and around something it perceives to be prey. These pseudopods then come together on the other side of the food, like hands cupping something. When they fuse, the lipid bilayers fuse into a vesicle, which is then brought inside the cell and filled with digestive enzymes. The prey is dissolved, the amoeba absorbs the products, and the vesicle is pushed to the edge, where it fuses with the outer cell wall, opens to the environment, and releases the leftovers outside the cell.

Now that you know what a vesicle is, and an example of one way it might be used, you should be able to answer this question, by thinking of another way a vesicle might be used, say, by a plant cell that makes its own poisons but doesn't want to kill itself.

Would anybody like to read Top Girls for me?

Next you'll be wanting us to sit the exam for you, too.

If you can somehow get a 6'6" guy to look like you, and get me to fly out there, I will.

I don't want to fail.

Can anyone help me with some calculus?

Find the average rate of change of the function over each interval.
5. f(x) = cot x, [pi/6, pi/2]

I use the definition of the slope of the tanget line thing. Slope of the secant line, whatever that is.

(f(t+h) - f(t)) / h

Problem is, when I replace cot x with 1/tan x (cause that's all I know about cotangent, that it's the reciprocal of tangent), plug everything into the equation and into my calculator (radian mode), I get an error. Answer key says there's an answer.

Being a grade 12 math student in conjunction with being a calculus student, I haven't learned this radian mode stuff yet, and I'm guessing there's some specific manual un-electronic way to solve this #5 thing up there. If anyone can roughly explain this all to me in layman's terms and help me come up with the answer in the right manner other than copying the answer key, it'd be muchly appreciated. :)
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[edit] One more question...this one not as weird, but still. *scratches head*

Find the slope of the curve at the indicated point.
f(x) = |x|, at x=2 and x=-3

I got so far as this:
lim h->0 (|x+h| - |x|) / h

Remember, tan(x) = sin(x)/cos(x).
Consequently, cot(x) = 1/tan(x) = cos(x)/sin(x).

Average rate of change = delta y / delta x = [cot(pi/2) - cot(pi/6)] / (pi/2 - pi/6) = [cos(pi/2)/sin(pi/2) - cos(pi/6)/sin(pi/6)] / (pi/2 - pi/6) = (0/1 - (sqrt(3)/2)/(1/2)) / (pi / 3) = -3*sqrt(3)/pi

f(x) = |x| can be defined by a piecewise function:

f(x) = x for all x >= 0
f(x) = -x for all x < 0

Thus, at x = 2, y = |x| has the same rate of change (derivative) as y = x, which has a slope of 1.

At x = -3, y = |x| has the same derivative as y = -x, that is, -1.

It is also probably important to note that f(x) = |x| is not differentiable at x = 0.


Edit: If you're just starting calculus, it might be better to calculate the derivative of |x| the rigorous way...i.e. with the limit approach you began.

The idea is actually the same, but applying it works like this:

f(x) = |x|

For all positive x, i.e. all x > 0, |x| = x (you can ignore the absolute value signs because x is positive anyways). Similarly, you can ignore the absolute value signs on |x+h| because as h->0, the expression is already positive so long as x is positive. So remove the abs. value signs from the limit:

lim h->0 (|x+h| - |x|)/h = lim h->0 (x+h-x)/h = lim h->0 h/h = 1 for all x > 0.

What about for negative x, i.e. all x < 0? Well in that case |x| = -x. Similarly, |x+h| = -(x+h) if x is negative. The fact that you're "adding" h (which could just as well be negative, because h->0 from both sides) is a non-factor---the fact that it goes to zero prevents it from changing the inside of the absolute value. Replace |x| with -x and |x+h| with -(x+h):

lim h->0 (|x+h| - |x|)/h = lim h->0 (-(x+h)-(-x))/h = lim h->0 -h/h = -1 for all x < 0.

And if x = 0? Well now we have a problem. Before, we knew what to replace the absolute values with so long as x > 0 or x < 0, because we knew the value of h would not affect the sign of the expression inside of the absolute value.

However, for x = 0, h becomes important. If h approaches zero from the left (written h->0-), THEN |x+h| is negative, and therefore equals -(x+h). If h approaches zero from the right (written h->0+), THEN |x+h| = x+h.

As you can see, lim h->0- =/= lim h->0+, and therefore, the limit does not exist, and consequently, the function is not differentiable at x = 0.

Let me know if this doesn't clear things up.

Ok, I'm really bad at rearranging equations, and I need to do some for my physics lab. We just got told the formulas two classes ago and the teacher just automatically assumed everyone could rearrange. >_> Anyway, here they are:

T = 2(pi) * (square root of) l/g I need to solve for g.

and

d = v*t + (a(t2)/2 I need to solve for a.
(the small 2 is squared)

The lab report is due tomorrow, so quick help is appreciated. With a good explanation I should be able to understand it from now on.

For a nice, concise answer to g, perhaps you can tell your teacher "g equals 9.81 m/s^2" if the pendulum is near the Earth's surface. But if not...

T = 2*pi*sqrt(L/g)

When solving for a variable, you want to isolate it on one side of the equation. First, we can "seperate" 2*pi from the right side by dividing both sides by 2*pi.

T/(2*pi) = sqrt(L/g)

To get rid of the square root, square both sides.

(T/(2*pi))^2 = L/g

If you multiply both sides by g, you'll find that:

g(T/(2*pi))^2 = L

Finally, isolate g by dividing both sides by (T/2*pi))^2:

g = L/(T/(2*pi))^2

d = vt + 1/2*a*t^2

Subtract vt from both sides.

d - vt = 1/2*a*t^2

Multiply both sides by 2.

2(d - vt) = at^2

Divide both sides by t^2.

(2d - 2vt)/t^2 = a

Ah, thanks a million! The point of the lab was to compare the average acceleration from 3 different experiments to see it it was the same. My results were fairly close, and I get leeway for experimental error, so I should be good. I think my main problem was trying to do everything at once.

It's a little funny to ask for english help, but .

From my english article, "...Megan's father, Eric, wax rhapsodic about the importance of being connected to the food one eats, the superiority of wild game to anything wrapped in cellophane on a grocery store meat counter and even the 'sacred' respect a hunter has for his or her quarry."

Can someone explain this sentence to me in simpler terms? I don't get it at all... what does the expression "wax rhapsodic" mean? And what do "the superiority of wild game to anything wrapped in cellophane..." and "'sacred' respect..." mean?


While I'm here, does anyone know about an alternate source of food that isn't too explored currently? It's for french, and their example was insects, but I have to think of another one. (my friend said that the only one she could think of was humans. -_-)

I've got a question too. It's from a maths test and our teacher and the whole class have different answers.

If ab<0, which of the following must be true?

i) a>0, b<0
ii) a<0, b>0
iii) a does not equal to 0, b does not equal to 0
iv) The signs (positive or negative) of a and b are diffirent.

(iv)
Any + number multiplied by - number is always a -
Use a calculator if you are doubtful

Actually more than one of them are correct, and we're supposed to proof it.

I say iii & iv, but my teacher thinks it should be i, ii & iv.

To "wax" is to emotionally say something. If I were talking about the woman of my dreams, I would "wax poetic." Use of the word "wax" requires that you use the adjectival form of the noun that follows it. So, rhapsody becomes rhapsodic, poetry becomes poetic, and so on.
The root of this usage comes from lunar cycles - when the moon is going from new to full, it is waxing, and when it is going from full to new, it is waning.

"Superiority of wild game to anything wrapped in cellophane" is the father ranting about how much he hates TV dinners, I believe. I haven't read the story you're referring to, but my guess is that he's trying to convince his daughter that hunted food is better than McDonald's.

As for "Sacred" - many ameroindian cultures viewed their relationship with their prey as a balance - the deer gave man meat, so man viewed the deer with respect.