# Tutor profile: Jenny N.

## Questions

### Subject: Biology

If a cell contains 0.1% salt in it's membrane, and the it's environment (outside the cell) is a 3.5% salt solution, is the cell in a hypotonic or hypertonic solution? And which direction will the water move during osmosis?

So the question is asking about solutes (stuff) in the cell and in the environment. And it is assuming that the solutes (salt) cannot penetrate the cell's membrane, while water can! So the water can move in and out of the cell, but the salt stays fixed either inside or outside of the the cell. First, let's establish that 0.1% < (is less than) 3.5%. That is all we will need from these numbers. So, visually, the cell has a little bit of stuff in it, and the environment has lots! We call this sort of solution, when there is more stuff in the environment than inside the cell a hypertonic solution. Now, let's return to the fact that the salt cannot move in or out of the cell, but that the water can! The water will move to make an equilibrium of water to solutes. So inside the cell picture just a few dots of solute (weak tea), while outside picture lots (strong, dark tea)! The water will move from low concentration to high concentration. It will move from the few dots, to the high dots. From the inside of the cell, to the outside. In essence, watering down the dark tea and making it lighter (while making the weak tea more concentrated)! So, in conclusion, the water will move from inside the cell into the solution.

### Subject: Anatomy

Why do shoulder separations occur so easily?

The shoulder reinforcements are weak (especially anterior and inferior) allowing the humerus to dislocate forward and down. The shoulder has such free range of motion due to few attachments and shallow socket.

### Subject: Algebra

How do you simplify 265.43 x 10^-7 ?

To simplify means that it will look like A x 10^B where A has only one digit before the decimal point. (right now it has 3 digits, 265) So, we have to change 265.43 to 2.65. To do that we are moving the decimal two places to the left which means two zeros! 00! So we are taking out 100. Which is also 10*10 = 100. Which can also be written 10^2. So, A is now 2.65 x 10^2. Now we have to move those tens into the exponent (B). Right now that exponent is -7. So we have ten to the negative seventh. And we now are multiplying two new tens from part A so we ADD exponents when they have the same base (in this case 10). 10^2 x 10^-7 = 10^ (2+-7) = 10^-5. So, B = -5. Now let's combine A and B back together. 2.65 x 10^-5

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