AP Biology Lab 5: Cellular Respiration
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AP Biology Lab 5: Cellular Respiration



hi it's mr. Andersen and welcome to the ap biology lab five walk through this is on cellular respiration and in order to do that in eukaryotic cells we need this which is the mitochondria basically what goes on in cellular respiration I'm not going to go into too big of depth but what we're doing is we're taking a sugar like glucose and in the presence of oxygen we're breaking that down into carbon dioxide water and we're producing energy in the form of ATP remember there are three different steps we have glycolysis which is going to occur outside of the mitochondria we have the krebs cycle which occurs inside the mitochondria we're going to give off carbon dioxide and we're going to produce nad and fad and then finally we have the electron transport chain where we're going to use the energy in that and fad to make ATP or to generate ATP but in this lab what we're really trying to do is measure the rate of respiration the rate of cellular respiration and we do that by measuring the rate at which oxygen is being consumed and so in this lab setup we're going to use two different things we're going to use worms and then we're going to use piece now you might think Peas well they don't respire of course they do in other words plants grow and they use photosynthesis to produce sugars but then they break down that sugar to produce ATP and energy and they're doing that so they can grow and so since this P is going to be underneath the soil it needs energy to grow and it's going to do that through cellular respiration okay so what do we use to measure this we're using something called a respirometer respirometer has important parts to it it's got a glass jar and you're on the bottom usually I'll put weights on the bottom so it's going to sink and I'll get to that in just a second on the bottom we're going to have some cotton and that cotton is going to have this chemical in it it's called potassium hydroxide potassium hydroxide will be at the bottom of in this some absorbent cotton down at the bottom basically what potassium hydroxide does is if it's ever in the presence of carbon dioxide it will convert that into a solid in other words if we were to put peas inside here they would take in oxygen but they would produce an equal amount of carbon dioxide and so that volume wouldn't change in here but since we have the potassium hydroxide it's going to convert any carbon dioxide that's produced into this solid so we really don't have to worry about its volume some other things that we'll use in this lab will use beads to make sure that we can account for temperature changes or fluctuations and also to keep the volume the same and then we'll use an equilibration period so basically how do you build it at the bottom you're going to put some of the Koh a little bit of cotton then you're going to put your pea seeds over the top of it then you're going to seal it we're going to have a little pipette like this now the three different types of the AP suggests oops let me go back for just a second okay now the three jars that ap suggests that we're going to have one where we're going to have peas in it where we're going to have one where we have dry peas or non germinating peas and then we're going to have one where we're going to use just glass beads now these glass beads are simply a control these ones are used to subtract our values to account for just fluctuations in the temperature and how that affects it so what we're really comparing is we've got germinating peas we've got non germinating peas and then we got worms and so we're not really going to concern yourself with this we'll use it to correct our values but we're looking at the respiration rate of worms germinating peas non germinating peas and see how that changes over time so let's look what happens we take our respirometer we're going to put it under water we're going to let it set and equilibrate and basically what you'll get is a little air bubble that forms right here so there's going to be oxygen inside here oxygen is going to go all the way out here and then water is going to start to creep in over here so now we let it sit so start at 0 and then 5 and then 10 and then 15 minutes and basically what's going to happen is that pee is going to start to consume oxygen it's going to produce carbon dioxide but remember that carbon dioxide will build up as a solid down here on the bottom so you don't have to worry about it so we're going to decrease the amount of volume inside the respirometer and then the water pressure is going to start to move this bubble farther and farther and farther in and so we can measure the rate at which this bubble flows in and that's going to be the rate of respiration it's kind of hard to read this under waters because your eye is going to be right up here at the top so you got to get used to that but it's a really simple elegant experiment that we can use to measure respiration what do we find well here's some data so here would be the beads alone again we're using that to UM just accommodate for any changes because temperature fluctuations are going to have a huge influence on this we now got our germinating peas dry peas and then worms and so we can subtract any changes inside the beads from these other ones to account for any changes in temperature but if you look at this person's data what they got is the steepest line and they should all be linear is going to be the germinating peas so the germinating peas are going to have a line like that so this is the milliliters of oxygen consumed then it's going to be time on the bottom so time in minutes and so the slope of this line if I were to figure out the slope of this line in milliliters oxygen consumed over minutes that's going to be the rate of respiration we'll find that that's a greater rate than that of the worm and a greater rate than that of the non germinating peas and that's because these ones are not activated they're not doing cellular respiration if we were to soak them in water then they would start to activate start to actually do those things and so we could do the rate of each of those then graph it and that would be a histogram of the of the rate or the change over time and so that's the respiration lab and I hope that's helpful

27 thoughts on “AP Biology Lab 5: Cellular Respiration

  1. hes my daddy ,if i was his son then he would laern everything from him sice hes the best and the coolest teacherssss ever .god sent worthy people like you if werent for you science class will be like world war 3.

  2. Does anyone understand the influence of temperature on the rate of cellular respiration? Like, what affect does and increase or decrease have?

  3. I can anyone explain why germinating peas have a greater rate of cellular respiration than the worms?

  4. Why is the equilibration period necessary? What happens during that period? I understand the rest of the experiment but that part is kind of glossed over in most explanations.

  5. KOH is a strong base, meaning that it dissociates completely in water. It also means that if any of it came in contact with the peas, the peas would be completely fried and the experiment wouldn't work. To correct this, we dip absorbent cotton balls into the KOH first, put it at the bottom of the respirometer, and cover it with NON ABSORBENT cotton. This provides a barrier between the KOH and the peas while still allowing O2 to pass through.

  6. Let me rephrase this for you:
    You're such an idiot. Religion was made up by a bunch of scholars who had nothing better to do with their lives than make up a false reason as to how humans came to be.

  7. If that statement were to have the slightest merit, it would be directed at evolutionary biology, the study of the origin and evolution of life. Biology is concerned with the biological systems that beget and appropriate life. If you're going to insult a science, you may want to make sure you're insulting the right one. But I'm sure the scientific community would love to hear your ideas of human origin and study the vast amounts of information that corroborate your hypothesis. Oh, wait…

  8. You're such an idiot. Biology was made up by a bunch of scholars who had nothing better to do with their lives than make up a false reason as to how humans came to be.

  9. I love your explainations! Btw, could you please please make a video on Cellular Respiration and the Kerbs Cycle? because when you explain it I understand completely and way better than me just reading off from the textbook! (the most difficult part is the process) Thank you for uploading so many wonderful videos! It really helped me lot ! 🙂 I can't wait for more of your videos! You rock!

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