Hello and welcome. This is a key stage 3 biology video for the process of respiration. Now before we begin today if you haven't already downloaded the work along sheet to work along with this video I'd advise you do that. If not at least have a notebook with your pens and stationery because this is a really important video that contains information that's the basis of work that you will do for GCSE and even if you go on to A level this would be important. So we're looking at respiration.
There are two key and important things we should remember about respiration. The first one is that respiration releases energy, releases energy from food and in particular the glucose that's found in food. So it releases energy from food, the glucose that's found in food.
The second thing that's really important to remember is that all living cells respire. or we could say carry out respiration and by all living cells we mean those cells from plants so living cells from plants living cells in animals and bacteria as well so all cells will respire to stay alive so two very important points about respiration now the next thing to look at is the idea of respiration in humans So we've got a small little diagram there showing the lungs and parts of the digestive system and if we were to take out some of these cells that carry out respiration from the body there's our cells there's an example of just a few of them there and those cells are supplied with blood as you can hopefully see by those blood vessels. So the first thing to remember is that oxygen from the lungs will be transported in the blood to those cells and glucose from food that you might have eaten is also transported in the blood to those cells. So we've got oxygen and glucose being provided and then as a result of this process of respiration we get the production of carbon dioxide, carbon dioxide, and we get the production of some water.
So carbon dioxide and water happens as a result of this process of respiration and those two again are carried away in the blood. Now very importantly those cells will carry out that process of respiration and they will release energy using the glucose and the oxygen and those cells will release the energy and use that energy to function and stay alive. This has a name, this process, this is called aerobic respiration.
Aerobic respiration. A very important process and we call it aerobic because it uses oxygen. We can write a summary equation.
We could say that glucose and oxygen will produce carbon dioxide and water. And to complete this equation we should add an arrow there. We also get the release of energy. And that we put at the end.
I've put that in a different colour because it's not a product. It's some energy that's released, not an actual substance. So that's aerobic respiration. Now let's have a look at a slightly different scenario.
Okay, so we've got the same cells. They are also being supplied with glucose that's come from food. from the digestive system so they're being supplied via the blood with some glucose but this time we've got a different scenario we haven't got carbon dioxide and water we actually have lactic acid we have lactic acid produced instead now this equation can be written like this glucose produces lactic acid and we can add our arrow here to make it into our summary equation But we also get the release of less energy. We get the release of less energy in this process. You can see there's no oxygen involved here.
And this happens when oxygen is not getting to the cells fast enough. We call this anaerobic respiration. Anaerobic respiration. That's respiration without the use of oxygen. So we have glucose that goes to lactic acid.
And just as a little note, it might be worth making a note that lactic acid is the thing, is the substance that causes fatigue. In other words, tiredness in muscles if you do some sudden heavy exercise, which includes... standing up and suddenly running around that's the substance that causes your muscles to become tired so again a very important summary here we've got two of our summary equations so important that it's worth highlighting those in a slightly different color to the rest because they are very important summary equations for respiration so a very important summary shown on this page of two processes related to respiration aerobic and anaerobic What we're going to do next is compare those two processes.
So the first thing to do when we say compare is to remember what we mean by compare or to do a comparison and that means to say things that are the same and things that are different. To compare means to show the things that are the same and the things that are different. It's really helpful if we can do the equation for each one. So pause here see if you can remember the equation for aerobic respiration.
If not, there it is. And then let's do the same on the other side for anaerobic respiration. See if you could pause here and remember what that is without looking at your notes. That was glucose goes to lactic acid for anaerobic respiration. If you can remember those two and write them down, it makes the comparison much easier.
So the first thing is for aerobic respiration, oxygen is required, or we could say oxygen is used, whereas For anaerobic respiration there is no oxygen. There is no oxygen used. For the second point, again using our equation, there's carbon dioxide. So we can say that aerobic respiration produces carbon dioxide whereas anaerobic respiration does not produce carbon dioxide or no carbon dioxide produced.
Very important that you write something on both sides here. So if you're saying that aerobic respiration produces carbon dioxide it's important that you also say that anaerobic respiration does not produce carbon dioxide because this is how we're comparing. One produces carbon dioxide the other one doesn't and you should know which way around it goes.
So important to complete both sides of that table. For aerobic respiration there is no lactic acid produced and on the other side we would say for anaerobic respiration that lactic acid is produced. Now one thing we can't actually see from those summary equations is the idea that for aerobic respiration more energy is released and for anaerobic respiration we have less energy released compared to aerobic respiration. And in fact one more thing you can spot by looking at the summary equations is the idea that for aerobic respiration water is produced whereas for anaerobic respiration there is no water produced.
So you can see how much easier this is once we know the equations. If we were to look at what things are the same for these two, so these are the differences we've said, but what things are the same? Remember we're comparing, we're finding things that are different and the same.
They both use glucose or both require glucose and they both release energy. Even though one releases more than the other, they both release energy. Remember, don't say the word produce when you're talking about energy. Don't say produce energy because energy is not a substance. We have to say either they release energy or they provide energy.
These two processes of aerobic and anaerobic respiration. Okay, so an important summary of a very important topic called respiration. This is for key stage three, but remember it's useful.
for GCSE and will be a good basis for your further studies if you carry on with biology.