Lesson video

Hello, and welcome to this lesson from the unit Plant Nutrition and Photosynthesis.

This lesson is called Plant Nutrition.

We're gonna be thinking about the things that plants need to keep them alive, including food and where they get these things from.

I'm Mr. Moore.

And if you're ready, let's get started.

So by the end of today's lesson, you should be able to describe what plants need from their surroundings to stay alive and to grow, and how they get their food.

And there are some key words to look out for in today's lesson.

The words are minerals, food, producer, and carbohydrate.

Now, you may have heard some of these words before.

You may have heard them in everyday life outside of school.

You may have heard them in your science lessons before, and you might think you know what they mean.

We're gonna look again at the meanings and perhaps define them in slightly different ways than you may have heard before.

But don't worry, we'll get to all of that as we go through the lesson.

Today's lesson is in three parts.

The first part is about what plants need to stay alive, the second part is about how they get their food, and the third part is about what plant food actually is and how plants make use of it.

So let's get straight into the first part, what plants need to stay alive.

Before we get into thinking about what plants need to stay alive, let's think about plants themselves, and why it is that we see that plants are alive.

So take a look at the screen.

What have we got? We've got four photographs, all showing different types of plants.

So we've got trees, we've got a sunflower, and other flowers.

We've got grass, we've got a dandelion growing in the grass.

Many people would call a dandelion a weed, but it is just a plant like all of the others.

And we've got a cauliflower that's a vegetable.

So all of these are examples of different types of plants.

There are other different types of plants, plants that produce fruits or beans, things that we can eat, and plants such as moss that I'm sure you've seen when you've been out and about.

What these all have in common is that they are all living things or to use the the proper biology vocabulary, they're all living organisms. But what does that actually mean? What is it that makes a living thing a living thing? You should already know some processes that happen in all living things.

So have a little think.

Think back to science lessons of the past.

And you will have learned a series of processes that happen in all living things including in living plants.

So just have a think.

If you've got somebody there to chat to, have a talk to them and share your ideas.

You might want to pause the video for a few seconds.

I'll be quiet for a few seconds and let you just have a think.

Note down a few processes that happen in all living things, including plants.

Okay, are you ready? So processes that happen in all living things include growing.

So plants grow, of course, they get bigger.

If we give them all the things they need to stay alive, they get bigger.

You may have grown plants yourself in the past.

You might have grown crests or sunflowers.

Hopefully, you've had a chance to grow some plants at some point.

So plants can grow and all living things grow.

And plants can also reproduce.

That's another process that takes place in all living things.

They can make new plants.

That's what reproduce means.

And what else? What are other processes happen in all living things do you think? Well, one of the processes that happens in all living things is movement, even in plants, plants can move.

You've probably seen a Venus flytrap closing, that's an obvious example, but other plants can move.

We've got a sunflower there in the picture.

If you've ever watched a sunflower over the course of a day it turns the flower to follow the sun.

So the flower is always pointing towards the sun and daisies do that as well in the grass.

All plants can move, believe it or not, even if it's usually too difficult for us to see it happening.

And moving often involves another process that happens in all living things.

And that is sensing, being sensitive to their surroundings.

So when a sunflower moves to follow the sun across the sky, it has to sense where the sun is.

So all living things, including plants can sense and respond to their surroundings.

And all living things can excrete.

That means getting rid of waste products.

So plants are made of cells, and chemical reactions happen inside the cells, and they generate waste products, and the plants have to get rid of those things.

So excretion, another process that happens in living plants and all living things.

And there are two more, and these are the two that are most relevant to our lesson today.

Two more things that happen in all living organisms. The first is nutrition.

So the title of the lesson today was Plant Nutrition, and nutrition is a process that happens in all living things.

It means that they need food and other nutrients to stay alive.

And then you might have learned about something called cellular respiration.

And this is another process that happens in all living organisms. And what that means is that the living organism uses food as a fuel, as a source of energy to provide the energy that the living thing needs to stay alive.

So we know that plants are living things.

And plants need particular things to keep them living, to keep them alive.

They need to take in certain things from their surroundings to stay alive, to stay healthy, and to grow.

One of the things they need to take in is water.

You must know this if you've grown plants yourself.

You have to give them water, otherwise they die.

Look at this plant on the left, the one that's standing up nice at tall and looking healthy.

That plant has certainly had plenty of water.

The other one is looking a lot less healthy.

It's very droopy, it's wilting.

That definitely needs some more water, that plant on the right.

So plants need water to stay healthy.

They actually use water to fill up their cells and to keep themselves standing upright.

It's a way of supporting themselves.

They don't have a skeleton like we do.

So filling themselves up with water helps to keep them standing upright.

It's a bit like a modelling balloon.

One of those big, long, thin balloons that you might twist up to make a model of a dog or something like that.

If you fill that up with water, you could stand it upright and it would support itself.

But if there was less water in there, it might be kind of drooping and wilting.

A bit like the plant on the right there.

So plants need water to stay healthy and to stay alive.

And they also need light.

I don't know if you've ever tried to grow plants in the dark, but it probably didn't go too well.

If you grow plants in the dark, they go very pale, and yellow looking, they look very unhealthy.

And also the stems get quite long because they're desperately trying to reach a place where there might be some light.

So plants need light to stay alive.

And it could come from the sun or it could come from an artificial light, a lamp, an indoor light, that kind of thing.

But plants need to get light from somewhere to stay alive, to stay healthy, and to grow.

Now, we're not, in this lesson today, we're not gonna go into why plants need light.

For now, it's just enough to know that they do.

It's one of the things they have to take in from their surroundings to stay alive.

So we know that plants need water and that they need light to stay alive.

They take in the water from their roots.

The roots are down there underground in the soil where it's dark and damp, and there's water for them to take up.

And they absorb light through their leaves.

Absorb is a bit of scientific vocabulary and it just means to take in.

So plants absorb light through their leaves because the leaves are above the ground where the light is, up there in the air where the light can get at 'em.

So plants take in the light through their leaves.

There are some other things that plants need to take in to stay alive, to stay healthy, and to grow.

They need to take in some gases from the air.

Now, we're not gonna go into those in too much detail today.

We will do that in another lesson.

But if you know something about cellular respiration already, you will know that plants need to take in oxygen for that process.

So that is one of the gases that they need to take in from the air.

And they do that through their leaves.

They also need to take in minerals from the soil.

They take those in through their roots.

Minerals are substances in the soil and they provide essential elements, such as nitrogen that the plants need to stay alive, to stay healthy, and to grow.

So now we know four things that plants need to take in from their surroundings to stay alive.

Water, light, gases from the air, and minerals from the soil.

So a quick check of what we've just learned.

What do plants take in through their roots? I will stay quiet for a few seconds to give you a chance to look at the answer options, and to make your decision.

You might want to pause the video and just hit play again when you're ready for the answer.

Are you ready? So what do plants take in through their roots? You should have picked two things here.

Water and minerals are the two things that plants take in through their roots.

And another quick check.

This time, what do plants take in through their leaves? Again, I'll give you a few seconds.

You might want to pause the video.

Have you decided? Okay, again, you should have picked two things here.

Plants take in gases from the air and also light through their leaves.

All right, let's see if we can practise that now.

So a little task for you to do.

We know that plants need to take in four things from their surroundings to stay alive.

You need to add these things to the diagram.

So add a label and an arrow to show what the name of the things are that the plant has to take in, and use the arrow to show where it goes into the plant.

We've done one of them already for you.

We've done the light, so you need to add the other three things.

I'll give you five seconds, but you might want to pause the video to give you time to add the things on.

Okay, hopefully you have labelled your diagram of a plant now with three things and three arrows to show where those things go in.

So the answers are that plants need to take in gases from the air and they do that through their leaves.

They take in minerals through the roots, and of course they take in water, and they take the water in from the soil through their roots.

So we've just been talking about things that plants need to stay alive, water, light, gas in the air, and minerals from the soil.

But we haven't really mentioned food yet, have we? So let's move on to the next part of the lesson, how plants get food.

All living organisms need food to stay alive.

We do, other animals do, and plants do as well.

We all need food to keep ourselves alive.

Humans and other animals are consumers.

Now, that's a bit of scientific vocabulary that you should have met before.

What do you think consumer means? Well, it means that we get the food that we need to stay alive by eating other organisms. So in this food chain, the human eats the cow, and the cow eats the grass.

What about the grass? The grass is a plant.

Where does it get its food? Well, plants are producers.

That is another scientific word that you should have met before.

And producer means that it makes its own food.

So that's why the plant is at the start of the food chain.

It doesn't need to eat anything.

It makes its own food.

It's a producer.

And in fact, every food chain on earth starts with a producer, not always a plant.

There are other organisms like algae, for example, microorganisms that live in the oceans that are producers as well.

But every food chain on earth starts with a plant or another producer.

All the food that moves through every food chain, all the way up to humans is made by plants and other producers.

And what does that mean? Well, it means that we're entirely dependent upon plants and other producers for all of our food.

If all the plants and all the producers died out, we could survive for a while by eating other animals, but then the food would eventually run out because there would be no more producers making the food to move up the food chain.

We are entirely dependent upon plants and other producers for all of our food, and therefore for our survival.

And that's one of the reasons why it's really important to take care of the environment, to protect biodiversity, to protect plants and other producers.

So a quick check before we move on.

This is a true or false.

Plants are consumers, true or false? I'll give you a few seconds to decide.

And the answer to that one is false.

Plants are not consumers.

Now, pick a reason why that is false.

Again, I'll give you a few seconds to read the two options and then decide what is the best reason for why that statement plants are consumers is false.

So the right reason is that plants make their own food, that is why they are not consumers.

So another quick check, another statement.

Plants are producers, true or false? I'll give you a few seconds.

And the answer this time is of course true.

Plants are indeed producers.

So again, two possible reasons here why that is true.

I'll give you a few seconds to decide.

So did you pick the right answer this time? The right answer was plants make their own food.

Again, that is why that statement plants are producers is true.

So we know that plants take in these four things, light, water, gases from the air, and minerals from the soil.

We know they have to take those things in from their surroundings in order to keep themselves alive.

But these things are not food.

Now, why is it important? Why have I said that quite so strongly? That's because a lot of people get this wrong.

It's very, very common for people to think that the things that plants take in from their surroundings are the plant's food, especially minerals from the soil, for example.

But that is not correct.

These things are not the plant's food.

So let's just think about that word food in a bit more detail.

Now, we use the word food a little bit differently in everyday life and in science.

So in everyday life we call lots of things food, meat, vegetables, cereals, bread, rice, all the things you eat.

We call lots of different things food.

When we use the word food in science, we use it very specifically to refer only to things that an organism uses as a source of materials for growth and repair and as a source of energy.

So if a living organism uses something in both of those ways, we call it food in science.

And if an organism only uses something in one of those ways, it isn't actually food, not technically in science.

So the things that we know plants take in from their surroundings aren't food.

And that's because the plant only uses each of those four things in one of those ways.

So it only uses each thing either as a source of materials for growth and repair or as a source of energy.

Now, we've thought about that word food in a lot of detail and that's because a lot of people get this wrong.

They think that those four things that a plant takes in are food and they're not, because of this very specific way that we use the word food in science.

Okay, let's do another quick check.

So in science, the word food means something that an organism needs to stay alive, takes in from its surroundings, uses as a source of material for growth and repair, uses as a source of energy.

Which of those do you think are correct endings to the sentence? I'll give you a few seconds to decide.

Are you ready for the answers? So you should have realised that option C was correct.

The word food means something that an organism uses as a source of materials for growth and repair, and also option D, that food is something that an organism also uses as a source of energy.

And another quick check of what we've just learned.

So we have a statement here.

Plants use water, gases from the air, minerals and light as food.

Is that true or is that false? I'll give you a few seconds to decide.

In this case, the statement was false.

And now I'd like you to pick a reason why it was false.

So I'll give you a few seconds to read through the answers and to make your decision.

You might want to pause the video this time because there's quite a bit to read.

So have you decided? The correct reason why the statement was false was reason A.

That plants actually only use gases, minerals, and water as a source of materials for growth and repair, and they only use light as a source of energy.

They don't use all of those things in both ways and that's why they are not food.

So we've got Alex here.

And Alex says that "Plants get their food from the soil." But Alex is actually incorrect.

And what we want you to do is to write three reasons why Alex is incorrect.

So I'll stay quiet for five seconds, but you might want to pause the video to give yourself time to write down three reasons why Alex is incorrect.

Are you ready for the answers? So Alex said that "Plants get their food from the soil." But he was incorrect.

There are actually quite a few reasons why Alex is incorrect.

You only need to get three of them.

So let's have a look through and you can see a few managed to get three of these.

So Alex is incorrect because plants make their own food.

They don't take in food from their surroundings, including from the soil.

Plants actually only take in water and minerals from the soil.

They don't take in food from the soil.

And water is not food because it's not used as a source of energy in the plant, and the same is true for minerals.

Minerals are not food because they are not used as a source of energy in the living plant.

So now we know how plants get food.

They're producers and that means they make their own food.

They don't take in food from the surroundings.

Now, let's move on to the third part of the lesson and think a bit more about what plant food actually is and how it's used in a plant.

So we know that plants make their own food.

And when we say make food in everyday life, what do we mean? Well, often we mean something like cooking, processes like that.

But that of course is not what's happening in a plant.

Plants make their own food inside their leaves and in other parts of the plant that are above the ground.

And the food that they make is carbohydrate.

Now that's a word that you will have met before when you learned about food groups, carbohydrates, fats, and proteins.

But the food that plants make in their leaves is just carbohydrate.

And that's it.

That is all the food that a plant needs.

The carbohydrate that's made in the leaves is then transported to all of the other parts of the plant to keep those parts alive.

Now that carbohydrate that's made in the leaves is all the food that a plant needs because they use it as a source of energy.

So earlier we mentioned the process of cellular respiration and that's a process that happens in all living things, including plants.

And that is the process of using food as a fuel to provide energy for all of the life processes that happen in the plant.

So plants use the carbohydrate food that they have made in their leaves as a fuel for cellular respiration, and that provides the energy that they need to keep all of their cells and all of their parts of the plant alive.

And also they use the carbohydrate food that they make as a source of materials for growth and repair.

So think back to that definition of food that we were exploring earlier.

In science, something is food if it is used by an organism as a source of energy and as a source of materials for growth and repair.

So the carbohydrate food that plants make, they are using it in both of those ways and that's why it's all the food they need.

So they're using it as a source of materials for growth and repair.

The carbohydrate that they've made is made up of the elements, carbon, hydrogen, and oxygen.

They can break that food back down again, and then use those elements, combine them with others, such as nitrogen that they get from minerals that they've taken in from the soil.

So they combine the carbon, hydrogen, and oxygen from their food with other elements such as nitrogen to make proteins and fats.

And it's the carbohydrate, the proteins, and the fats that they use to make up all of the cells, and tissues, and organs that they need to grow and to keep themselves alive.

So let's have a quick check of what we've just gone through.

What type of food do plants make for themselves? Three options, I'll give you a few seconds to decide.

The correct answer to this one is carbohydrate.

That is the food that plants make for themselves in their leaves.

And another quick check.

How do plants use this carbohydrate food that they've made? I'll give you a few seconds to read through the answer options.

You might want to pause the video while you do that, and then press play again when you're ready for the answer.

So how do plants use the carbohydrate food that they've made? Well, the answer is C.

They use it as a source of both energy and materials for growth and repair.

Right then, to finish off the lesson, let's try to apply everything that we've learned today to a real world example.

So let's think about these bottles of stuff that you can buy that call themselves Plant Food.

You might have seen these at home, you might have seen them in a garden centre, bottles of stuff called Plant Food.

So Kyle has got a bottle of something called Plant Food, but it's run out.

And Kyle is worried that his plant is going to die if he doesn't give it any more of this stuff called Plant Food.

So what we want you to do is to write some advice for Kyle.

So there are some issues here that we need to help Kyle to understand.

So A, whether plants need to be given food to stay alive.

B, how plants get the food that they need to stay alive.

And C, whether Kyle should buy another bottle of this stuff called Plant Food.

So I'll stay quiet for five seconds, but you will want to pause the video for this one to give yourself time to write some advice to Kyle in those three issues.

Let's look at the answers then.

So some useful advice for Kyle would include the following things.

So A, plants don't actually need to be given food by humans.

I mean, think of all the trees, and the grass, and flowers, and all the other plants outside.

We don't feed them, they make their own food.

That's because they're producers and they make carbohydrate food in their leaves, and that is all the food they need.

They don't need to be given food by us.

So what about this stuff in the bottle called Plant Food? Well, it contains minerals and they are useful to the plant, but they're not actually food.

The plant is making all the food it needs for itself.

So we don't need to give it any more food.

But this stuff in the bottle does contain minerals.

And plants need minerals to stay alive, to stay healthy, and to grow.

So the plants make carbohydrate food and they will use that.

They will combine it with elements such as nitrogen, that they get from minerals to make proteins and fats to make all of the cells, and tissues, and organs that they need to grow.

And that's why it might be useful to give the plant something called Plant Food, even though it isn't actually food.

So to end our lesson today, let's run through a quick summary of what we've learned about plant nutrition.

Plants are living organisms and they need certain things to keep them alive and to grow.

So they need light, water, minerals from the soil, and gases from the air.

They take in light and gases from the air through their leaves, and they take in the water and the minerals that they need through their roots.

But they also need food to stay alive and to grow.

They don't take in food from their surroundings.

Plants are producers and that means they make their own food in their leaves.

And the food the plants make is carbohydrate, that is all the food they need.

And they use that carbohydrate food as a source of materials for growth, and as a source of energy for all of the other life processes that take place in the plant.

That's it for today's lesson.

I hope you've enjoyed it.

Do have a go at the exit quiz.

And we will see you in the next lesson.