Lesson video

Hello, everyone.

How are you today?

I hope you're feeling good.

My name is Ms. Panchal and I'll be a teacher for this lesson.

I'm feeling good about that because we have an interesting topic ahead of us.

We are looking at plants, we're looking at photosynthesis and plants absorbing light.

A lesson is called "Adaptations of plants for photosynthesis: absorbing light.

" I hope that sounds interesting to you.

A lesson comes from the unit of work, plant nutrition, and photosynthesis.

So if you're ready to dive into this topic, if you have some energy, focus and enthusiasm, we'll begin our lesson now.

The outcome for today's lesson is I can describe how plants are adapted to absorb light for photosynthesis.

I hope this sounds interesting to you.

We have some keywords in our lesson and I'd like us to go through them one at a time saying them out loud.

My turn, your turn.

Chloroplasts, adaptation, chlorophyll, surface area.

Good to hear those keywords out loud.

And now I'd like you to turn to someone and tell them, 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.

Let's find out what these keywords mean.

Photosynthesis takes place in chloroplasts, which are small structures inside some plant cells.

An adaptation is a feature that helps an organism to function and survive.

Chloroplast contain a green substance called chlorophyll, which absorbs light for photosynthesis.

The surface area of the top side of a leaf is the area through which light can be absorbed.

So here are our keywords, chloroplasts, adaptation, chlorophyll, and surface area.

Let's look out and listen out for them.

Let's think carefully about these keywords.

They'll be coming up in our lesson today.

Our lesson is called adaptations of plants for photosynthesis: absorbing light, and it has two learning cycles, adaptations of plant cells for photosynthesis and adaptations of leaves for absorbing light.

Let's begin by exploring adaptations of plant cells for photosynthesis.

Plants make their own food using photosynthesis.

Photosynthesis happens in leaves and other parts of the plant above the ground.

Photosynthesis needs energy from light.

We can see a beautiful image of some sunlight and leaves of a tree absorbing the sunlight, creating their own food through photosynthesis.

Leaves are made up of cells.

Photosynthesis takes place inside the cells.

Here, we can see the leaf of a maple tree.

What a beautiful shape, beautiful color.

And here, we can see the leaf cells seen through a microscope.

Pause here and share with someone any of the details that you can notice in this image of leaf cells.

Thanks for sharing.

Plant cells have some parts in common with animal cells.

Pause here and share with someone if you have any idea what some of these parts could be.

Thanks for sharing.

Let's take a look at what are some of these parts of plant cells, which they have in common with animal cells.

There's a nucleus which stores the cell's DNA, and controls the cell's activities.

The cytoplasm, this is a jelly-like substance where most chemical processes happen, then is the cell membrane, which controls movement of substances into and out of the cell.

And mitochondria where aerobic cellular respiration takes place.

So these are parts of the plant cells which they have in common with animal cells.

Nucleus, cytoplasm, cell membrane, and mitochondria.

Plant cells also have some parts that animal cells don't have, including permanent vacuole, where cell sap, a mixture of water and other substances is stored, cell wall, which strengthens and protects the cell.

And chloroplasts with photosynthesis takes place.

So these are parts of a plant cell, which they do not have in common with animal cells, permanent vacuole, cell wall, and chloroplasts.

Let's have a check for understanding.

I'd like you to complete the labels on a diagram of a plant cell.

So pause here while you label these six parts of a plant cell.

So how did you get on with labeling the parts of a plant cell?

Here's the nucleus.

Did you label the mitochondria in the center of of vacuole?

At edge, we have the cell wall and then the cell membrane and we have chloroplasts.

Well-done.

If you labeled the diagram of a plant cell in this way, let's have another check for understanding.

I'd like you to match each part of the cell to its function.

So here are the parts of the cell chloroplasts, mitochondria and nucleus and functions, stores the cell's DNA, where cellular respiration takes place and where photosynthesis takes place.

So pause here while you match each part of the cell to its function.

Did you match the parts of the cell to their functions in this way?

Chloroplasts are where photosynthesis takes place.

Mitochondria are where cellular respiration takes place and the nucleus stores the cell's DNA.

Well-done if you matched the parts of the cells to their functions in this way.

In biology, an adaptation is a feature that helps an organism to function and survive.

Chloroplasts are an adaptation of plant cells that enables plants to photosynthesize.

And there, we can see the chloroplasts and this diagram of a plant cell.

Not all plant cells have chloroplasts.

This diagram shows a cell from a root.

It does not have chloroplasts.

It does have a vacuole, mitochondria, and nucleus, cell wall, and cell membrane, but it doesn't have chloroplasts.

Cells in the leaves do have chloroplast because there is light for photosynthesis.

Let's have a check for understanding what is an adaptation.

Choose from this selection.

A, a feature that helps an organism to function and survive, B, part of the plant cell.

We'll see the structure where photosynthesis takes place.

So pause here while you decide what is an adaptation.

Well-done if you selected answer A.

Indeed, an adaptation is a feature that helps an organism to function and survive.

And now it's time for your first task.

The diagram shows a cell from a plant root.

We can see the mitochondria, the nucleus, the vacuole.

Explain why the root cell does not need to have chloroplasts.

So pause here while you have a go at this explanation task explaining why the root cell does not need to have chloroplasts.

I'll see you when you're finished.

It is good to be back with you.

So how did you get on with that task of explaining why the root cell does not need to have chloroplasts?

Perhaps your explanation when something like this chloroplasts or where photosynthesis takes place.

Photosynthesis needs energy from light and the plant's roots are underground.

There is no light underground, so that's why a root cell does not need to have chloroplasts.

Well-done if you gave an explanation like this.

Well-done for having a go at this task and now we're onto our next learning cycle.

Adaptations of leaves for absorbing light.

Leaves are made up of cells containing chloroplasts.

You can see the cell wall.

And then inside the cell, we see some chloroplasts, in this closeup of a leaf cells seen through a microscope.

So fascinating.

Chloroplast contain a green substance called chlorophyll.

Photosynthesis can only happen when it's light.

So we have the light which in the leaves and a chlorophyll in the leaf cell absorbs light.

The light provides the energy needed for the chemical reactions of photosynthesis to take place.

That's why it can only happen when there is light.

Let's have a check for understanding.

Complete the sentences about photosynthesis.

Use some of the words from the list.

Chlorophyll, chloroplasts, light, mitochondria, oxygen.

And here are our sentences.

Photosynthesis takes place in structures called inside the cells of plant leaves.

These structures contain a green substance called, this substance absorbs for photosynthesis.

So pause here while you choose from this list of words which ones you'll use to complete these three sentences.

Did you complete the sentences in this way?

Photosynthesis takes place in structures called chloroplasts inside the cells of plant leaves.

Next, these structures contain a green substance called chlorophyll.

And finally, this substance absorbs light for photosynthesis.

Well-done if you completed the sentences about photosynthesis in this way.

Most leaves are very thin.

Take a look at the leaf from that angle.

Really rather thin.

Hmm.

And why is that?

I wonder.

Leaves are made of layers of cells.

Light is more likely to pass all the way through a leaf if it is thin, leaves are adapted to be thin.

So light can reach all the cells containing chloroplast.

And we can see here the light is coming in through the top of the leaf and then it's passing through the leaf, hitting all those chloroplasts all the way down to the bottom of the leaf, which is why it is useful for a leaf to be thin so that the light can reach all the cells containing chloroplasts.

Let's have a check for understanding.

Complete the sentences about leaves.

Use some of the words from the list.

Chloroplasts, cytoplasm, mitochondria, thick, thin.

And here are the sentences, leaves are adapted to be.

This allows light to pass through the leaf and reach all the cells that contain.

So pause here while you complete sentences about leaves using some of the words from the list.

Did you complete the sentences about leaves?

In this way, leaves are adapted to be thin.

This allows light to pass through the leaf and reach all the cells that contain chloroplasts.

Well-done if you completed the sentences about leaves in this way.

Light for photosynthesis is mostly absorbed through the top side of a leaf.

The top side of a leaf has a surface area.

This is the area of the leaf through which light can be absorbed.

Leaves are adapted to have a large surface area.

Having a large surface area means the leaf can absorb more light.

More light equals more photosynthesis, which equals more food is made.

To calculate the area of a square or rectangle, we multiply its length by its width, so the area and centimeter squared equals the length times the width.

The surface area of this piece of leaf is three centimeters times three centimeters, which equals nine centimeters squared.

And now it's your turn.

I'd like you to calculate the surface area of this piece of leaf, which is three centimeters by six centimeters.

Pause here while you do this.

Well-done if you calculate it, the surface area as being three centimeters times six, which equals 18 centimeters squared, that's the surface area of this piece of leaf.

Leaves are not usually square or rectangular in shape.

Leaves have an irregular shape.

We can estimate the surface area of the leaf.

Each square has an area of one centimeter squared.

To estimate the total surface area of the leaf, we count up the squares that are at least half filled with leaf.

Include squares like these in the count, once that are fully filled with leaf and those are at least half filled with leaf.

Take the square on top there.

Do not include squares like these in the count, as there's either no leaf or less than half the square filled with leaf.

So let's estimate the surface area.

The total number of squares at least half filled with leaf is 30 for this leaf.

So the estimate of total surface area of leaf is 30 centimeters squared.

Announce your turn.

I would like you to estimate the total surface area of this leaf.

Remember to count up the squares that are at least half filled with leaf.

Well-done if you counted that, the total number of squares at least half filled with leaf is 13, which gives us an estimate of total surface area of leaf of 13 centimeters squared.

And now it's time for your task.

Here's a question for you.

Which leaf has the largest surface area?

Leaf one or leaf two?

And note the measurement of 0.

5 centimeters for the length and width of each square.

So pause here while you calculate which leaf has the largest surface area.

And remember that we'll be counting up the squares that are at least half filled with leaf.

So pause here while you have a go at this task of calculating which leaf has the largest surface area.

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?

So for leaf one, the total number of squares at least half filled with leaf are 13.

The estimated surface area equals 0.

5 times 0.

5 times 13 equals 3.

25 centimeters squared.

And for leaf two, the total squares more than half filled with leaf is 10.

So the estimated surface area equals 0.

5 times 0.

5 times 10, which equals 2.

5 centimeters squared.

So leaf one has the largest surface area.

And now for the next part of your task, imagine 16 plant cells arranged in two different ways.

His arrangement one and his arrangement two.

Which arrangement of cells is the best adaptation for photosynthesis?

Explain your answer.

Pause here while you do this.

So how did you get on with that task of explaining which arrangement of cells is the best adaptation for photosynthesis?

Perhaps you said something like this.

Arrangement two is the best adaptation for photosynthesis.

This is because arrangement one is thicker, so light may not be able to pass through all the layers of cells to the ones at the bottom.

Arrangement two has a larger surface area, so can absorb more light.

Well-done if you had an explanation like this.

Well-done for having a go at this task.

In our lesson, adaptations of plants for photosynthesis absorbing light, we've covered the following.

The cells that make up leaves contain small structures called chloroplasts, where photosynthesis takes place.

Chloroplasts contain a green substance called chlorophyll, which absorbs light for photosynthesis.

Chloroplasts are an adaptation of plant cells that enables them to photosynthesize.

Plant leaves are adapted to be thin, to allow light to pass through the leaf to reach all the cells containing chloroplasts.

Plant leaves are adapted to have a large surface area to absorb light for photosynthesis.

Well-done everyone for joining in with this lesson.

I thought it was so interesting to explore adaptations that plants have made so they can absorb more light, so they can make more food, so that photosynthesis can take place effectively.

Allowing in more light is key.

I hope you enjoyed this lesson and learned some new information, I certainly enjoyed teaching you, and I'm looking forward to seeing you at another lesson soon.

Until then, stay curious.