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Hi. It's Mr. Andersen and in this video I'm going to talk about the temperature
coefficient or Q10. This was added to AP Biology this year. And to be honest I'd never even
heard of it before. But what it is is a ratio. It allows us to see what happens to the rate
of reaction as we increase temperature 10 degrees. That's where the 10 comes from. If
we define it, its the factor by which a rate R of a reaction increases for every 10 degrees
rise in the temperature. But you have to remember that we don't have to measure two temperatures
that are exactly 10 degrees apart to find an answer. So let me give you an example of
this. Imagine we have a goldfish. It's in a bowl and it's 17 degrees celsius. Now in
order to use Q10, you'll have to use celsius or kelvin to come up with your values. But
let's say we're measuring its respiration rate. How do we do that? Well the goldfish
on the side are going to have these operculum. And as they breathe they're going to open
up those operculum and we could count the number of breathes per minute and that's going
to be their respiration. So let's say at 17 degrees celsius the respiration rate is 110
operculum movements per minute. And let's say we cool them off with a little bit of
ice. And now it's 10 degrees and they're going to breathe at a slower rate. So it's a fun
lab you can slow it way down and they almost come to a stand still. Because they're ectotherm.
But now we really have all we need to calculate Q10. So we've got two temperatures. T1 and
T2. And then we have two rates, R1 and R2. And this is going to be the equation right
here. So make sure that you're units are going to match, but all you do is divide your second
rate by your first and then your going to raise it to an exponent where we're subtracting
T2 - T1. And so let's throw these values into our equation. So what do we get 110 divided
by 62. Again, that's our second rate minus our first rate. And then we're going to raise
that to the power of 10 divided by our second temperature 17 minus our first, which was
10. And so let's simplify it a little bit. I get 1.77 raised to the 1.43. I plug that
in my calculator and I get 2.26. So that would be my Q10 value. It's not going to have any
units. It's simply a ratio. Now one thing I found interesting is the Q10 values in biological
systems are usually going to be somewhere between 2 and 3. And it's nice to know what
you're answer is going to be. Now this would be hard to solve with a four function calculator.
In other words how could you do that if we don't have a power button. Well, what I'm
thinking is we could put values up here that make this an easier problem. And so let's
say they put 15 and 10 here, that would be 10 divide by 5 which would be a squared value
and you should be able to solve that. Or maybe they won't even ask you questions about that
on the test as well. But it's a cool concept. To measure as we increase temperature, what's
happening to the rate of the reactions? So what Q10s could we measure? In other words,
what are our possible Rs? Well we could look at the velocity of a nerve impulse along a
peripheral nerve in meters per second. Those could be our two rates. And then we could
measure that at different temperatures. Or we could look at products being produced in
a reaction and that could be our R. Or we could look at heart contractions in ectotherms.
Or we could look at water transported through an aquaporin over time at different temperatures.
And so it really doesn't matter what you're reaction rate is. If we look at two temperatures,
we should be able to calculate Q10. And I hope that was helpful.