Lesson video

Welcome to this lesson from the Unit: Cells.

The lesson title is Plant cell structures and their functions.

Today we're gonna be looking at those living building blocks that make up all living organisms called cells, and in this case, the cells that make up plants.

Within those cells there are little structures, so we're gonna be looking at the names of those little structures and what the jobs are or the functions.

My name's Mrs. Barnard, and by the end of today's lesson you should be able to name the common structures in plant cells and be able to describe what these structures do, their functions.

So as with all our science lessons, we've got some keywords to look out for today, and our keywords in today's lesson are cell wall, chloroplast, and vacuole.

So your definitions for these words are as follows.

Now, if you want to pause the video and write these down to refer back to them later, then that's fine, but I will be defining them as we go through the lesson today, so don't worry.

Our lesson today is going to be in three parts.

Part one, is the common structures of plant cells.

Part two, is the functions of those structures that are within plant cells.

And then three is comparing cells.

So let's get started with our very first part today, which is common structures of plant cells.

So a little bit of a recap.

First of all, cells are the building blocks of all living organisms. So you should have come across animal cells by now, but they make up all living organisms on earth.

Plants are living organisms. Sometimes people think that they aren't, but they are living, because they carry out those common processes, movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition.

So they are living, and therefore they're made up of cells.

And just a reminder that cells are very, very small, so you can't see them without a microscope.

So therefore, in order to see these cells that are in this picture on this slide, that are part of a leaf, you would have to look at a very thin section down a microscope in order that the microscope could magnify those cells to see.

Okay, look, all of these plants look really different.

You can have a massive, massive tree.

You can have very, very small flowers, cactuses, lily pads, little pond weed, even the leaves that you eat, like lettuce.

But they are all living organisms, they're all plants, and they're all made up of cells.

And because they're all made up of plant cells, they have very similar structures.

Here is an image of a plant cell, and a plant cell has all of the same structures as an animal cell.

So let's remember what those are.

It's got a nucleus, and a cell membrane.

It's got cytoplasm, and it's got mitochondria.

In addition to this, they also have this big structure in the middle, which is a vacuole, a cell wall around the outside and chloroplasts.

So let's have a look at the labels for those now.

We've got chloroplast there.

They look a little bit similar to the mitochondria in their distinct structures with sort of this oval shape, but sort of sausage-shaped, or spherical, if we were to think about them in 3D.

And then we've got the vacuole.

So this is this big structure in the middle of the cell, and finally the cell wall.

Now the cell wall can cause a little bit of confusion, because all cells have a cell membrane, and a plant cell does have a cell membrane, you can see it labelled there.

But around the outside of the cell membrane, it also has a cell wall.

So time for a quick check.

So from this list below, can you choose two structures that appear in both animal and plant cells? So I'll give you a few seconds to think about that.

Okay, how did you do? So two structures that appear in both animal and plant cells are a cell membrane and a nucleus.

Okay, so if you've got that right, then well done.

Let's move on to a practise task.

So we've got Laura here and she's looking at images of cells and she's trying to identify the plant cells.

She says, "I think cells A and B are plant cells, as they look the most similar." So what I would like you to do is decide whether you think she is correct.

And when you've decided, I'd like you to write an explanation for your answer.

You're gonna need a little bit of time to do some writing here, so if you pause the video, and then you come back and we'll go through your answers.

Okay then, let's see what you thought.

So just a reminder that Laura was looking at these images of cells and she decided that A and B were plant cells.

So cell B is a plant cell, but cell A isn't, even though they look similar.

Cell B has a cell wall, chloroplast and a vacuole, that's what makes it a plant cell, where cell A doesn't have those things.

Cell C is not a plant cell, as it again doesn't have chloroplasts, a cell wall or a vacuole.

But plant D does have those things even though it's a different shape, and therefore it is a plant cell, because it does have a cell wall, vacuole and chloroplasts.

Okay, so if you've got those right, then well done.

So it's time to move on to the second part of our lesson today, which is the functions of the plant cell structures.

So all of those structures that we looked at previously all have a specific job.

However, some of those structures are the same as those that you've learned about in the animal cell.

So let's have a little bit of a reminder of those now.

So first of all, we've got the nucleus.

Now the nucleus contains the DNA, which is your genetic information, and that controls all of the activities of the cell.

So all living organisms will need that information in order to control their cells.

And in plant cells, this is stored in the nucleus, the same as in an animal cell.

Okay, the next one is the cytoplasm.

So the cytoplasm is a jelly-like substance, and that is where all of the reactions of the cell take place.

And next, we've got the cell membrane.

It's got a really important job, because it surrounds the cytoplasm and it controls what enters and leaves the cell.

So it's how the cell can take in nutrition, but it's also how it can get rid of waste.

So controlling what comes in is really important to keeping the cell alive, but also controlling what it gets rid of is really important as well.

And then we've got those mitochondria.

Now mitochondria use food as fuel to provide energy for the cell so it can carry out all of those activities that we've already discussed that happened in the cytoplasm.

Now that process of releasing energy from food is called respiration.

Now all living organisms respire, and it is one of the common processes of living organisms. So now let's have a little look at the stuff that's in a plant cell that isn't in an animal cell.

So these are new.

So these are gonna be our new key terms for today's lesson.

And we did refer to those right at the start of the lesson.

So here's our first one, which is chloroplast.

Now chloroplasts are green, and their job is to trap sunlight so the plant can make food.

You might have learned about this before that plants take in sunlight and they can use it to make food.

And these are the little structures that are involved in that job.

Okay, you might have heard that the job is called photosynthesis.

But making food is something that is unique to plants and they need chloroplast in order to be able to do that.

Their plant cells has also got a cell wall.

Now a cell wall is made of fibres and that strengthens the plant.

It can be a little bit confusing, because inside the cell wall is the cell membrane.

And remember that controls what enters and leaves the cell.

So the cell wall does have to let things through, so there are holes between the fibres.

But it's there to give structure to the cell.

And then we've got the vacuole.

Now vacuoles is this big structure in the middle that's filled with like a watery sap.

Now when that's really filled up, it's gonna push on the outside of the cell and that pushes on the cell wall and it makes the cell really firm.

But then when the plant isn't watered enough and that vacuole shrinks, because it hasn't got enough fluid inside it, what then happens is, all of the cells in the plant become less firm, and then the plant looks really floppy.

You might have noticed that if you don't water a plant for a while that it looks all floppy.

And then when you give it some more water, all of those vacuoles will fill up with water again.

So, time now for a quick check.

So what I'd like you to do is match the part of the cell to the correct description of its role.

Now you'll need a couple of minutes to do this, so pause the video and we'll see how you've got on.

Okay, how did you do? So, let's check.

So, a cell wall is made of fibres to strengthen the cell, and then a cell membrane controls which substances enter and leave the cell.

A chloroplast is where the light is trapped to help make the plant's food.

And then a vacuole contains a watery sap and helps keep the cell firm.

So good job if you've got all of those correct.

Let's take that knowledge and move it onto a practise task now.

So, plant cells are living building blocks of plants, and they carry out the common processes of living organisms. You can see here's a picture of a plant cell just to help you, because for this task, you're going to need that picture.

What we'd like you to do is explain why the plant cell is described as living.

So you need to use the plant cell diagram, but also your knowledge of the jobs of those cell structures, which we've just discussed in the previous slides.

But also your knowledge of the common processes of living organisms, which you've learnt previously, and which I went through nearer the beginning of this lesson.

You don't need to talk about all of the common processes of living organisms, just the ones that are relevant to these structures.

So you'll need a little bit of time to do some writing.

So pause the video, and then we'll come back, and we'll have a look at how you did after.

Okay, let's have a look at how you got on.

So explain why the plant cell is described as living, and we're gonna use that picture.

And we're also going to use our knowledge of the jobs of those structures, the functions, and the common processes of living organisms. So first of all, we've got your chloroplasts.

So the chloroplast trap light, and they use it to make food, and that's the plant's nutrition, and nutrition is one of the common processes.

Next, we've got mitochondria.

And the mitochondria use the food as fuel to release energy for the cell's activities, and that's respiration, that process.

And respiration is one of the common processes.

And then the other labelled part of that cell was the cell membrane.

And the cell membrane's job is to control what enters and leaves the cell.

So that means that it can control the food that enters the cell that can be used for nutrition, but also the waste products of that cell from its reactions, and that's excretion.

So we've got nutrition and excretion.

Now if you managed to link in some of the other common processes into your answers, then that's really good, but these were the ones that are linked to the image on the slide before.

Okay, well done for that.

Now we're going to move on to the third part of our lesson, which is comparing cells.

So below is a model, a 2D model of a plant cell with its structures.

So that's like the model that we've been looking at in the previous slides.

But not all plant cells actually look like this, they come in different shapes and sizes.

Here's some examples.

So we've got one here, and then another one, you can see they look quite different from each other, but they are all plant cells.

They can vary in shape, but also in the structures that they contain.

And the reason is because they're adapted for their job in the plant and their function.

Let's have a look at a couple of them.

So here we've got a palisade leaf cell and a root hair cell, and you can see they look quite different from each other.

And the plant cell here, its main job, is to absorb sunlight in order to make food, because in the leaf, and that's the main job of the leaf, it's to take in that sunlight, it's to make food for the plant.

So in order to do that, it's gonna need a lot of chloroplasts.

So that's what it has.

But then if we have a look over here at the root hair cell, its job is to take in water, because all the water that a plant takes in is from the ground.

So that root hair cell is part of the root network.

And can you see its shape here? It's got a really large surface area, and that means it can take in lots of water for the plant.

Also, notice it does not have any chloroplasts.

Because chloroplast absorbs sunlight, and because a root hair cell is under the ground, therefore it doesn't need any chloroplasts, even though it is still a plant cell.

So let's have a look at some other cells.

We've come across some of these before, but let's just compare them side by side.

So we've got an animal cell, a plant cell, and a fungi, so let's see what they have in common.

So they've all got a nucleus, because they need somewhere to store that genetic material, that information that controls the cells' activities, and these three all store it in the nucleus.

And they have a cell membrane that controls what enters and what leaves the cell.

What else? They've all got cytoplasm because cytoplasm is where the cells activities take place.

And they've all got mitochondria, 'cause mitochondria use food as fuel in order to release energy in a process called respiration, and all living things carry out respiration.

But now we've got a few differences.

The animal cell you can see isn't labelled in this diagram, because the plant cell and the fungi cell both have a cell wall.

And the cell wall's job is to keep the cell really firm, because when the vacuole fills up, particularly in a plant cell, it pushes out on the outside of that cell wall and it makes sure that the cell is really, really firm.

You can see that the vacuole in the plant cell is much larger than in the fungi cell, but they both have them.

The plant cell has chloroplasts, but the fungi cell doesn't have chloroplasts, because it doesn't absorb sunlight to make food.

So time for a quick check.

Now this is called a Venn diagram.

What I'd like you to do is place these words in the correct area of the Venn diagram, to show whether the cell has these structures.

If you think the structure only belongs to one of the cells, then you need to place it in the far left, the far right, or the bottom, right by the title.

If you think it belongs to two of them, then place it in the area that overlaps two of them.

And if you think that the structure is in all three of the cells, then place it in the middle section.

So you'll need a little bit of time to do this, so pause the video and come back when you're ready.

Okay, let's see how we did.

So, we have got an animal cell, a plant cell, and a fungi cell.

And we have got in the middle, that they all have a cell membrane.

They all have mitochondria, they all have cytoplasm, and then they all have a nucleus.

But a plant cell and a fungi cell have vacuole, and the plant cell and a fungi cell have a cell wall, and only a plant cell has chloroplasts.

So well done if you've got those in the right area.

Venn diagrams can be quite tricky, but they're a good way of comparing things to each other.

So let's have a little bit of a practise.

So this time we're gonna be looking at microscope images.

So you've got two pictures here, and they're both plant cells, so they're both images of plant cells down a microscope.

In the first image you can see there's chloroplasts.

and in the second image there isn't.

So I would like you to suggest why the cells in the second image don't contain chloroplasts.

And then for your second question, these are two pictures, two images of cells, but the first one is a plant cell, and the second one is an animal cell.

So I want you to suggest what might happen if an animal cell had a vacuole like the plant cell.

So you might wish to discuss these first before answering the questions, and then pause the video, and then we'll come back and we'll have a look at the correct answers.

Okay, let's see how you did.

So, suggest why the cells in the second image don't contain chloroplasts.

So the second cell may be underground, or it could be part of a root, and therefore there's no light underground.

So the chloroplasts' job is to absorb light and make food, so therefore chloroplasts aren't needed in the root.

So if you've got that one right, well done.

Second one I think is a little bit more tricky, let's see what you've got here.

So, suggest what might happen to the animal cells if they had a vacuole like the plant cell.

So vacuoles contain cell sap, and they keep the cell firm by pushing out on the cell wall.

But if an animal cell had a vacuole, it might burst.

And the reason is because it doesn't have a cell wall, so therefore it wouldn't be strengthened, and when the vacuole pushed out on it, the cell membrane would burst.

So if you got that one right or you got close to the correct answer for that one, then well done.

Okay, we've come to the end of our lesson now.

So time to just summarise what we've learned today.

So plant cells have some common structures.

Some of these structures are common with animal cells such as cytoplasm, cell membrane, nucleus, and mitochondria.

Plant cells have additional structures including the cell wall and vacuole, and some of them have chloroplasts.

Each structure in a plant cell has a specific function or job.

And plant cells can vary in their shape and the structures they contain, depending on their role, because they are adapted to their role in the plant.

Well done for your work in today's lesson.