Lesson video

Welcome to this lesson from the Oak National Academy.

Today's lesson is about aerobic cellular respiration in humans and other organisms, and it's taken from the unit Aerobic and Anaerobic Cellular Respiration.

Hiya, I'm Mrs. Wheate, and I'm gonna be your teacher for today's lesson.

By the end of today's lesson, you will be able to describe the reactants and products of aerobic cellular respiration and explain where, why, and when it takes place.

Let's have a look at our keywords.

Today's lesson has four keywords and I'm gonna read them through now.

Cellular respiration, an exothermic chemical process that transfer energy for life processes, using glucose as a fuel.

Exothermic, a chemical process that transfers energy to its surroundings.

Aerobic, a process that requires oxygen.

Mitochondria, sub-cellular structures involved in aerobic cellular respiration.

If you wanna read through this again, I'm gonna be quiet for five seconds, but if that's not enough time, you can click pause and then click play when you're ready to move on with the lesson.

Today's lesson is in two parts.

First of all, we'll talk about cellular respiration generally, and then we'll talk about a specific type of cellular respiration called aerobic cellular respiration.

But first, cellular respiration.

Cellular respiration is a chemical process that uses glucose as a fuel to transfer energy for life processes.

That's quite a long sentence and it's got a lot of abstract ideas in it.

We're gonna spend the first part of today's lesson looking at a different part of that sentence, and that will help us in our understanding of what cellular respiration is.

So we'll start by talking about glucose.

So chemical that uses glucose as a fuel, what is glucose? So glucose is a sugar.

Now plants and other producers make the sugar glucose by photosynthesis.

Here are my picture.

I've got some plant leaves because that's where, leaves are where photosynthesis takes place in plants.

So plants use cellular respiration to transfer energy for life processes, but they get their glucose from photosynthesizing.

Humans and other consumers, we don't photosynthesize.

We digest carbohydrates, like this pasta, and sugary foods, like these sweets, and that releases the glucose that we need in order to carry out cellular respiration.

Okay, let's see if you understood that.

Which statements about cellular respiration are correct? a, it is a process that creates energy for cells, b, cells use glucose as a fuel in cellular respiration, c, it takes in energy from the surroundings, d, it transfers energy for life processes.

Take five seconds, or if you want some more thinking time, click pause.

Click play when you're ready to see the answer.

Okay, let's look at the correct answers.

The correct answers are b, cells use glucose as a fuel in cellular respiration.

d is also correct, cellular respiration transfers energy for life processes.

So a is incorrect, energy can't be created or destroyed.

It's transferred from one energy store, such as a chemical energy store, to another, such as a kinetic energy store.

c, it takes in energy from the surroundings.

That's also incorrect, and we'll talk about why that's incorrect in a few slides time.

Well done if you got those right.

Cellular respiration transfers the energy that is needed for life processes.

Life processes are the things that happen inside organisms that need to happen in order for that organism to stay alive.

So life processes that require energy include muscle contraction, active transport of substances through some membranes.

An example of that is plants use active transport to move minerals in the soil, which are at a low concentration.

So use active transport to move those minerals into the root where there might be a higher concentration of minerals.

And another example of a life process that requires energy is metabolism.

So here in my picture, I've got an enzyme and a substrate.

So the substrates are going into the enzyme, that active site, and they're coming out as one product.

So that's an example of making a substance.

Maybe those two substrates are amino acids and they're being joined together and eventually, they'll be joined together to make a protein.

So those are just three examples of life processes that require energy from cellular respiration to take place.

So respiration is takes place continuously in every living organism.

That's because all these life processes, these things that need to happen for all this to stay alive are happening continuously.

So you need a continuous supply of energy and respiration is what is supplying, what is transferring the energy for those things to happen.

So if a cell stops respiring, it will eventually die because none of these live processes that require energy will be able to take place.

Okay, let's see if you understood that.

True or false? Living organisms can survive without respiring.

Is that true or false? Take five seconds or pause the video.

Click play when you're ready to see the answer.

That is false.

Okay, why is it false? Again, take five seconds to think about why it might be false, or pause the video if you want some more thinking time.

Click play when you're ready to see the answer.

It is false because cellular respiration is an essential life process that continuously transfers the energy that organisms need to stay alive.

If living organisms don't respire, they die.

Well done if you got that right.

Cellular respiration is an exothermic chemical process.

Now, chemical process, what I mean by that is that it's lots and lots and lots of chemical reactions.

Let's talk about the exothermic part of that.

So exothermic chemical reactions are reactions that transfer energy to the surroundings.

So animals such as mammals and birds use this energy that's transferred to surroundings to maintain a constant internal body temperature.

So human beings are internal body temperature is around 37 degrees Celsius and that is maintained by our cells respiring.

And it's important that our body temperature stay consistent, stay at 37 degrees wherever possible, so that our enzymes can function at their optimum.

Okay, let's see if you understood that.

True or false? Cellular respiration is an exothermic process.

Is that true or false? Take five seconds, or if you want more thinking time, click pause.

Click play when you're ready to see the answer.

It is true.

Why is it true? Can you explain why cellular respiration is an exothermic process? What does that word exothermic mean? Take five seconds, or if you want some more time, click pause.

Click play when you're ready to see the answer.

It is true because cellular respiration transfers energy to the surrounding environment, and those kinds of chemical processes or chemical reactions, we refer to those as exothermic.

Well done if you got that right.

This is the first practise task of today's lesson, so we're gonna have a think about everything we've learned and apply that to this task.

Sam has written some notes about cellular respiration but there are some mistakes.

Every bullet point contains one mistake.

Identify the mistake and rewrite Sam's notes.

So here are Sam's notes: Cellular respiration is a chemical process that takes place in some living organisms. It is an endothermic process, which means it transfers energy to the surroundings.

Cells need to carry out respiration during the daytime.

In cellular respiration, water is used as a fuel.

This creates energy for life processes to occur.

Okay, so every single one of those bullet points has one mistake in it.

Try and identify the mistakes and then rewrite the notes correctly.

You'll need to pause the video now to give yourself enough time to do that.

Click play when you're ready to see the answers.

Good luck.

Let's have a look at the answers.

Cellular respiration is a chemical process that takes place in all living organisms, not some living organisms. It's an essential life process, happens in all living organisms, bacteria, elephants, fungi, all of them.

It is an exothermic process, which means it transfers energy to the surroundings.

Cells need to carry out respiration continuously, all the time.

Not just during the daytime, not just during the nighttime, constantly.

In cellular respiration, glucose, the sugar glucose is used as a fuel, not water.

This creates energy, we've talked about that before, energy can't be created or destroyed.

This transfers energy for life processes to occur.

Okay, well done if you got those right.

We've completed the first part of today's lesson.

We've defined cellular respiration and we've looked at that definition in a lot of detail.

Now we're gonna talk about a specific type of cellular respiration, aerobic cellular respiration.

There are two main types of cellular respiration: aerobic and anaerobic.

We're just gonna talk about aerobic right now.

Aerobic cellular respiration is a type of cellular respiration that takes place using oxygen.

If we look at that phrase, the aerobic part of the phrase, that means requires oxygen.

Hopefully that will help you remember.

So cellular respiration is not just one chemical reaction.

You might remember I've been calling it a chemical process, and what I mean by that is it's a series of chemical reactions that happen inside cells.

So it's not a chemical reaction, it's not just one chemical reaction rather, but it is still useful to summarise the reactants and products of aerobic cellular respiration.

So usually when we use equations, it's just talking about one chemical reaction.

These are chemical equations that are summarising a whole process.

So they're not telling the whole story, but they're giving us a really good summary of what's going on.

So you've got word equations, a balanced symbol equations.

The reactants of aerobic cell respiration are oxygen and glucose, and in a balanced symbol equation, we represent those like this.

Okay, and then we have our arrows, so these react to make our products.

So in our word equation, oxygen plus glucose reacts to make water and carbon dioxide, and this is how we represent our water, carbon dioxide in a balanced symbol equation.

Okay, let's see if you understood that.

What is the correct word summary of aerobic cellular respiration? Is it a, glucose reacts to make water plus carbon dioxide, b, glucose plus oxygen reacts to make water and carbon dioxide, c, glucose plus carbon dioxide reacts to make oxygen plus water, d, carbon dioxide plus water reacts to make glucose plus oxygen? Take five seconds.

If you want more time, click pause.

Click play when you're ready to see the answer.

Okay, the correct answer is b, glucose plus oxygen reacts to make water plus carbon dioxide.

Remember that in aerobic cellular respiration, oxygen is required, so oxygen's gonna have to be one of the reactants.

And it's a form of cellular respiration, which is a process that uses glucose as a fuel, so glucose is gonna be one of the reactants.

Well done if you got that right.

Let's have a go at another one.

What is the correct balanced symbol equation for aerobic cellular respiration? Take five seconds to read this through and pick the correct answer, or if you want some more time, click pause.

Click play when you're ready to see the answer.

Okay, the correct answer is a.

Let's have a look at why the other answers are wrong.

b and d have all the correct symbols and they're all balanced properly.

However, the reactants and products are mixed around or in the wrong order.

c is in the correct order but the symbol equation is not balanced.

For example, there's six carbon atoms in the reactants but only one carbon atom in the product.

And remember, these equations aren't telling us absolutely everything that's going on in the whole of cellular respiration.

They are just useful summaries of the whole process.

Well done if you got that right.

Now let's talk about where aerobic cell respiration occurs.

In eukaryotic cells, aerobic cell respiration happens in the mitochondria.

I've got three different eukaryotic cells here.

Can you tell me the name of each of these types of cells? So take five seconds or pause the video if you want some more thinking time.

Click play when you're ready to see the answer.

Okay, our first one is an animal cell.

You can tell that 'cause it's just got a cell membrane.

Our next one is a plant cell.

You could have figured that out by looking.

It's got a cell membrane, a cell wall.

It's got a vacuole, and it's also got chloroplasts.

Our last one is a fungal cell.

It's got a cell wall, it's got a cell membrane, but it doesn't have any chloroplasts.

So in these eukaryotic cells, cellular respiration takes place in their mitochondria.

Let's look at cellular respiration in the context of the mitochondria.

So glucose is broken down, the products of glucose enter the mitochondria, got oxygen is used, and energy is transferred for life processes.

Carbon dioxide and water are made as waste products, and the inside of the mitochondrion contains enzymes that catalyse the chemical reactions that are taking place here.

Powerful microscopes have enabled us to observe the inside of mitochondria.

There are many folds of membrane inside mitochondria, and the chemical reactions of aerobic cellular respiration occur across these membranes.

The folds increase the surface area, therefore increasing the rate of aerobic cell respiration.

And you can see those folds in this image of a mitochondria observed using electron microscope.

If you've used a light microscope at school, you may have been able to see mitochondria but you definitely won't have been able to see the detail inside mitochondria.

This is because light microscopes are nowhere near as powerful as electron microscopes.

Light microscopes have a maximum magnification of around 400, whereas electron microscopes have maximum magnification in the millions, around 5,000 times higher than that of a light microscope.

The invention of electron microscope helped us understand so much more about cell biology because electron microscopes are able to observe the fine detail of sub-cellular structures that wasn't able to be seen before when we were just using light microscopes.

Prokaryotic cells, including bacteria, don't contain mitochondria.

They're too small.

Mitochondria are bigger than prokaryotes, so they can't fit inside them.

But some prokaryotes do still carry out aerobic cellular respiration.

And in these cells, aerobic cellular respiration, well, it can't occur in the mitochondria.

It doesn't have any mitochondria.

It occurs in the cytoplasm and across the cell membrane of these cells.

Okay, let's see if you understood that.

Truth or false? Aerobic cellular respiration takes place in the mitochondria of bacterial cells.

Is that true or is that false? Take five seconds, or if you want more time, click pause.

Click play When you're ready to see the answer.

That is false, but why is it false? Take five seconds or, again, if you want some more thinking time, click pause.

Click play when you're ready to the answer.

It's false because bacteria do not contain mitochondria.

They do carry out aerobic cellular respiration but they do this in their cytoplasm and across their cell membrane.

Well done if you got that right.

This is the last practise task for today's lesson.

Answer the questions and complete the task below.

One, write a definition of cellular respiration, two, describe the importance of cellular respiration to living organisms, three, the following question is about summarising aerobic cell respiration, a, state the word equation for aerobic cellular respiration, b, state the balanced symbol equation for aerobic cell respiration.

Number four, for the following examples, state which part of the cell aerobic cellular respiration occurs in, so a, a plant cell, b, a yeast cell, c, an animal cell, d, a bacterial cell.

You'll need to pause now to give yourself enough time to think about your answer and write it down.

Click play when you're ready to see the answers.

Good luck.

Let's have a look at the answers.

Number one, write a definition of cellular respiration.

Cellular respiration is an exothermic chemical process that uses glucose as a fuel to transfer energy for life processes.

Number two, describe the importance of cellular respiration to living organisms. Cellular respiration transfers all the energy an organism needs to carry out life processes, including active transport and metabolism.

3.

a, state the word equation for aerobic cellular respiration.

Oxygen plus glucose reacts to make water plus carbon dioxide.

3.

b, state the balanced symbol equation for aerobic cellular respiration.

Okay, here it is.

I'll give you a few seconds to check that your answer is the same as that answer.

Four, for the following examples, state which part of the cell aerobic cellular respiration occurs in.

So for a, b, and c, they all have the same answer, they all occur in the mitochondria because they're eukaryotes.

Bacterial cell is a prokaryote, doesn't have any mitochondria, so aerobic cellular respiration occurs in the cytoplasm and across the cell membrane.

Well done if you've got those right.

Great, final question in our task.

Question number five, mitochondria were discovered in muscle cells in 1857.

Muscle cells have many more mitochondria than skin cells.

Explain why.

So again, you'll need to pause the video to give yourself enough time to think about that and write down your answer.

Click play when you're ready to see the answers.

Good luck.

Let's have a look at the answer.

Muscle cells need energy to contract.

This energy is transferred by cellular respiration.

Having more mitochondria means more aerobic cellular respiration can take place, which transfers more energy for muscle contraction.

Well done if you got that right.

Amazing work today.

Hope you enjoyed learning about aerobic cellular respiration.

Let's summarise what we've learned to help us remember it.

Cellular respiration is an exothermic chemical process that transfers energy for life processes, using glucose as a fuel.

Aerobic cellular respiration requires oxygen.

Remember that cellular respiration isn't a single chemical reaction.

It's a series of chemical reaction.

And because it is such a long series of chemical reactions with many, many, many steps, it's useful to summarise it as a word equation or a balanced symbol equation.

Aerobic cellular respiration can be summarised in the following ways: Here's the word equation, oxygen plus glucose reacts to make water plus carbon dioxide, and beneath it, we had the balanced symbol equation.

I'll give you a few seconds to read that through for yourselves.

In eukaryotic cells, aerobic cell respiration occurs in the mitochondria, and in prokaryotic cells, aerobic cellular respiration occurs in the cytoplasm and across the cell membrane.

Well done on today's lesson, and I hope to see you again soon for our next lesson.