Lesson video

Hello, everyone.

How are you doing today?

I hope you're feeling really good.

My name is Ms. Afzal and I'll be your teacher for this lesson.

I'm feeling very pleased about that because we got an interesting topic ahead, looking at Adaptations of Plants for Photosynthesis: Gas Exchange and Stomata.

That's the title of our lesson.

It comes from the unit of work Plant Nutrition and Photosynthesis.

So I wonder, do you know much about this topic?

Is it a new to you?

Whatever is the case, don't worry.

We're gonna be getting into it.

We're going to be exploring this today.

So if you're ready with some focus, energy, and enthusiasm, we'll begin our lesson now.

The outcome for today's lesson is I can describe how plants are adapted to take in and release gases to support photosynthesis.

I hope that sounds interesting to you.

We have some keywords in our lesson.

I'd like us to go through them one at a time saying them out loud.

My turn, your turn.

Gas exchange.

Stomata.

Guard cells.

Diffusion.

Net movement.

Good to hear those keywords.

And now I'd like you to share with someone, have you heard of any of these keywords before?

Do you have any idea what these keywords mean?

Pause here and share with someone.

Thanks for sharing what you already know about these keywords.

Let's find out their meanings.

Gas exchange in plants is when photosynthesizing leaves take in carbon dioxide gas and release waste oxygen gas.

Stomata are small holes in the surfaces of the leaf.

Guard cells are cells next to stomata that can change shape to open and close the stomata.

Diffusion is caused by the continuous random movement of particles of a gas or of a liquid.

And net movement is when more particles of a gas or of a liquid diffuse from an area of higher concentration to an area of lower concentration.

So these are are keywords, gas exchange, stomata, guard cells, diffusion, and net movement.

Let's look out for them.

Let's listen out for them.

Let's think carefully about these keywords, which will be coming up in our lesson today.

Today's lesson is called Adaptations of Plants for Photosynthesis: Gas Exchange and Stomata.

And it has three learning cycles.

Photosynthesis and gas exchange, adaptations of leaves for gas exchange, diffusion and gas exchange.

So, let's begin by exploring photosynthesis and gas exchange.

Plants make their own food using the process of photosynthesis.

Photosynthesis takes place in cells that make up the plant's leaves.

The food that plant cells make using photosynthesis is glucose, a type of carbohydrate.

In this cross-section of a leaf, we can see in between the top and the bottom of the leaf various cells.

And we will be finding out more about what happens in these cells shortly.

Photosynthesis is a series of chemical reactions.

The word summary for photosynthesis is the reactants of water and carbon dioxide produce the products of glucose, which is created, and oxygen, which is released as a waste product.

So this is the word summary for photosynthesis.

Water plus carbon dioxide leads to glucose and oxygen.

One of the reactants of photosynthesis is carbon dioxide.

Plants get carbon dioxide for photosynthesis from the air.

Plants take in carbon dioxide gas from the air through their leaves as we can see in this image.

One of the products of photosynthesis is oxygen, and oxygen is a waste product of photosynthesis.

Plants release oxygen gas into the air from their leaves as we can see in this image.

The movement of carbon dioxide gas into leaves and oxygen gas out of leaves is called gas exchange.

And we can see the arrows on the screen showing us this gas exchange.

The carbon dioxide is going into the leaves and the oxygen gas is coming out of the leaves.

This is gas exchange.

Let's have a check for understanding.

Join the boxes to describe the process of gas exchange for photosynthesis.

So we have carbon dioxide gas and oxygen gas.

And then the next part of the process either moves out of or moves into.

And then finally, the leaves or the roots.

You choose how you'd like to join these boxes to describe the process of gas exchange for photosynthesis.

Pause here while you do this.

Did you join the boxes to describe the process of gas exchange for photosynthesis in this way?

Carbon dioxide gas moves into the leaves and oxygen gas moves out of the leaves.

Well done if you joined the boxes in this way.

And now it's time for your first task.

A farmer grows plants in a greenhouse.

The farmer decides to add some extra carbon dioxide gas to the air inside the greenhouse.

I would like you to explain two things.

One, how the plants will make use of this carbon dioxide gas.

And two, how will this benefit the farmer?

So pause here while you have a go at this task of explaining how the plants will make use of this carbon dioxide gas and how this will benefit the farmer.

Pause here and I'll see you when you're finished.

It's good to be back with you.

So how did you get on with that task of explaining how the plants will make use of this carbon dioxide gas?

Perhaps you said something like this.

The plants will take in the carbon dioxide gas through their leaves.

The carbon dioxide will be used as a reactant in photosynthesis.

And this will make glucose food to support the plant's growth and survival.

And next, how will this benefit the farmer?

Perhaps you said something like this.

More carbon dioxide gas in the air means the plants can photosynthesize more, which means they will grow bigger.

So the farmer will get a bigger crop.

Good thinking from the farmer.

And now it's time for our next learning cycle.

Adaptations of leaves for gas exchange.

If we look at the surface of the leaf using a powerful microscope, we see that there are tiny holes in the leaf surface.

Pause here and share with someone.

Can you remember what these holes are called?

It's one of our keywords.

Well done if you said stomata.

That's what these holes are called.

And we can see them being pointed out on this image.

These are the stomata.

Leaves are made of layers of cells.

So we can see there between the top and the bottom of the leaf, various layers of cells.

The stomata, the holes, in the leaf surfaces lead to spaces between the cells.

The spaces are filled with air and we can see on the diagram one of the leaf stomata and we can see the air space above it in between the cells.

Stomata are an adaptation for photosynthesis.

Stomata allow carbon dioxide gas to move into the leaf for photosynthesis and waste oxygen made by photosynthesis to move out of the leaf.

And we can see the arrows on the screen showing us the carbon dioxide moving into the leaf and the oxygen moving out of the leaf through the stomata.

Let's have a check for understanding.

Complete the sentences about how plant leaves are adapted for gas exchange.

Here are the sentences.

There are holes called in the surface of plant leaves.

Gas for photosynthesis moves in through holes.

Gas made by photosynthesis moves out through the holes.

So pause here while you complete these sentences about how plant leaves are adapted for gas exchange.

Perhaps you completed the sentences in this way.

There are holes called stomata in the surface of plant leaves.

Carbon dioxide gas for photosynthesis moves in through the holes.

Oxygen gas made by photosynthesis moves out through the holes.

Well done if you completed the sentences about how plant leaves are adapted for gas exchange in this way.

The word stomata refers to the holes in the leaf surface.

So here we can see the leaf surface seen through a microscope.

So incredible to see that detail.

And here can see a diagram of cells around one of the stomata.

Each of the stomata is surrounded by two guard cells and we can see them there either side of the stomata.

Guard cells can change shape to open and close the stomata.

On the left, you see this stomata is open and then on the right the guard cells have changed shape so now the stomata is closed.

Water vapor, water in the gas state, can move out of leaves through open stomata.

Closing the stomata can help to prevent the plant from losing too much water through its stomata.

Let's have a check for understanding.

Which of the labeled structures are guard cells?

A, B, or C.

Pause here while you decide.

Well done if you selected A.

And now it's time for your next task.

Sometimes stomata are open, sometimes they're closed as we can see in these two diagrams.

Let's hear some opinions.

Lucas, "I think stomata are more likely to be open during the night.

" And Izzy, "I think they're more likely to be open during the daytime.

" Hmm.

They can't both be right?

I'd like you to talk with your partner who do you agree with, Lucas or Izzy?

And explain your answer.

So pause here while you have this discussion and share your explanation with your partner.

Enjoy your task and I'll see you when you're finished.

It's good to be back with you.

So how did you get on with that task?

Who did you agree with?

Lucas who thinks that the smarter are more likely to be open during the night?

Or Izzy who thinks they're more likely to be open during the daytime?

And how did you explain your answer?

Perhaps you said that Izzy has the correct idea and maybe you gave an explanation like this.

Stomata are more likely to be open during the daytime while it's light.

This is when photosynthesis can take place.

Stomata open to allow carbon dioxide gas to move into the leaf for photosynthesis and to allow oxygen made by photosynthesis to move out.

Photosynthesis cannot take place at night.

Stomata to close at night to prevent the plant from losing too much water.

Well done if you answered in this way.

Well done for having a go at this task.

And now we're onto our final learning cycle, diffusion and gas exchange.

Carbon dioxide gas and oxygen gas are made up of particles.

We can see some particles of carbon dioxide gas on the left and particles of oxygen gas on the right.

The particles move all the time in random directions.

This movement causes diffusion.

Diffusion is what causes particles of carbon dioxide and oxygen to move into and out of the air space inside a leaf through open stomata.

So again, let's look at this diagram.

So we've got the top surface of the leaf, the bottom surface of the leaf, and layers of cells in between.

And there at the bottom we have the opening of the stomata.

Diffusion that's causing the particles of carbon dioxide to move into the leaf and are particles of oxygen to move out.

Particles of a carbon dioxide diffuse into the air space inside the leaf through open stomata as we can see in this diagram.

They diffuse into leaf cells where they're used as a reactant in photosynthesis.

Again, as we can see through those arrows, particles of oxygen gas made by photosynthesis diffuse out of cells into the air space and then out the leaf through the open stomata, as shown by the arrows on the diagram.

Leaves are thin, which keeps the diffusion distance short.

This allows cells to be supplied with carbon dioxide gas quickly so they can keep photosynthesizing.

Waste oxygen made by photosynthesis to be removed quickly.

It's an efficient process.

Let's have a check for understanding.

Which process moves particles of gases through open stomata?

Choose from the selection.

A, adaptation, B, diffusion, C, photosynthesis.

Pause here while you decide which process moves particles of gases through open stomata?

Well done if you selected answer B, it's diffusion, which is the process that moves particles of gases through open stomata.

If particles of a gas are more concentrated in one area and less concentrated in another area, this creates a concentration gradient.

As we can see in this diagram, more of the particles will be moving from the area of higher concentration to the area of lower concentration than are moving in the opposite direction.

This is called the net movement.

When leaf cells are photosynthesizing, they use up the carbon dioxide from the air space inside the leaf.

This means there are fewer particles of carbon dioxide in the air space inside the leaf than there are in the air space outside the leaf.

The concentration gradient is from outside to inside.

The net movement of carbon dioxide particles is from outside to inside.

When leaf cells are photosynthesizing, they fill up the air space inside the leaf with waste oxygen.

This means there are more particles of oxygen in the air space inside the leaf than there are in the air outside the leaf.

The concentration gradient is from inside to outside.

The net movement of oxygen particles is from inside to outside.

Let's have a check for understanding.

Complete the sentences about diffusion of particles of a gas.

Use some of the words from the list.

Equal, gradient, higher, lower, movement, net.

And here are the sentences.

If particles of a gas are more concentrated in one area than another, this creates a concentration.

More of the particles will be diffusing from the area of concentration to the area of concentration.

This is called the movement.

So pause here while you complete the sentences about diffusion of particles of gas.

Using some of the words from the list.

Did you complete the sentences in this way?

If particles of a gas are more concentrated in one area than in another, this creates a concentration gradient.

More of the particles will be diffusing from the area of higher concentration to the area of lower concentration.

This is called the net movement.

Well done if you completed the sentences about diffusion of particles of a gas in this way.

And now it's time for your final task.

I would like you to complete the diagrams to show the diffusion of carbon dioxide and oxygen particles through open stomata when leaf cells are photosynthesizing.

I'd like you to draw particles to illustrate the concentration gradient and add an arrow to show the direction of the net movement of the particles.

So you've got two diagrams, one for carbon dioxide particles and one for oxygen particles.

So pause here while you have a go at this task and I'll see you when you're finished.

It's good to be back with you.

So how did you get on with that task?

Let's have a look at the carbon dioxide first of all.

Did you draw more carbon dioxide particles outside the leaf and less carbon dioxide particles in the air space inside the leaf?

And did you draw an arrow to show the net movement of carbon dioxide particles is going from outside to inside the leaf?

How about oxygen?

Did you draw a greater concentration of particles inside the air space and less oxygen particles outside the leaf?

And did you draw an arrow to show that the net movement of oxygen particles is from inside to outside the leaf?

Well done if you completed the task in this way.

In our a lesson Adaptations of Plants for Photosynthesis: Gas Exchange and Stomata, we've covered the following.

Plant leaves take in carbon dioxide gas from the air for photosynthesis.

The oxygen made by photosynthesis is released as a gas from leaves into the air.

This process is called gas exchange.

Leaves have small holes in their surface called stomata for gas exchange.

Guard cells can change shape to open and close stomata.

Particles of carbon dioxide gas and oxygen gas move through open stomata by diffusion.

Well done, everyone, for joining in with this lesson.

It was so great to explore the adaptations that plants have made for photosynthesis.

I loved exploring the stomata, the guard cells, and the net movement of different particles in and out of the leaf.

What an incredible process is photosynthesis.

I hope you enjoyed exploring it.

I've certainly enjoyed teaching you and I look forward to seeing you at another lesson soon.

Until then, stay curious.