Lesson video

Hello and welcome to this lesson from the Oak National Academy.

Today's lesson is called Producers, photosynthesis and consumers, and it's taken from the unit, Photosynthesis, requirements and products.

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

By the end of today's lesson, you'll be able to explain why the survival of consumers depends upon photosynthesis in producers.

Let's have a look at our keywords.

Today's lesson has five keywords and I'll read them out now.

Producer, an organism that makes its own food.

Photosynthesis, the process used by producers to make their own food by a series of chemical reactions.

Biomass, the mass of biological material in one or more organisms. Cellular respiration, a chemical process that transfers energy for life processes, using glucose as a fuel.

And consumer, an organism that eats another organism for food.

So if that wasn't enough time to kind of absorb those, I'll be quiet for five seconds.

You can read through them again.

But if that's still not enough time, feel free to click pause and then to click play when you're ready to move on with the lesson.

Today's lesson is in three parts.

First, we'll talk about the word producer and photosynthesis.

Then we'll introduce the term consumer, and we'll talk about the relationship between producers and consumers.

And then finally, we'll talk about the relationship between producers and the atmosphere.

But first of all, let's get started by talking about what a producer is and what photosynthesis is.

All living organisms need food to stay alive and grow.

And this is a common life process of nutrition.

But not all living organisms need to eat.

Can you explain why? Take five seconds, or if that's not enough time, pause the video and click play when you're ready to move on with the lesson.

So, not all organisms need to eat because some organisms are producers, and that means that they make their own food in their cells.

We've got some examples of producers here, including, so plants that grow on land such as grasses, trees, and flowers.

Or aquatic plants that grow in water.

But also microorganisms. So organisms that are too small to see with the naked eye.

You need a microscope to see them.

Microorganisms such as algae.

Which of these organisms are producers? A, vegetable plants.

B, grass.

C, freshwater green algae.

Or D, pollinators.

Take five seconds, or if that's not enough time, click pause and click play when you're ready to see the answer.

Let's look at the answers.

Which of these organisms are producers? A, vegetable plants are producers.

So are grasses, freshwater algae, but not pollinators.

Well done if you got that right.

Producers are really incredible organisms because they make their own food using the process of photosynthesis.

Photosynthesis is a series of chemical reactions that happen inside the cells of producers.

And because it's such a long chain of chemical reactions, it could be useful to summarise this.

A word summary of the reactions of products of photosynthesis is, so we've got carbon dioxide and water.

Those are reactants.

And those react to make glucose and oxygen.

Light energy is also involved.

So light transfers the energy in order for the chemical reactions of photosynthesis to take place.

But it's not a reactant and it's not a product because it's not a physical substance.

It's not made of matter.

It's a energy store.

The reactants and products of photosynthesis are all made up of carbon, oxygen, and hydrogen.

Let's have a look at that.

So here we have our carbon dioxide, which is made of one carbon atom and two oxygen atoms. Our water, which is made of one oxygen atom and two hydrogen atoms. So those react to make glucose.

Glucose is made up of six carbon atoms, 12 hydrogen atoms, and six oxygen atoms. And we also have oxygen.

Two oxygen atoms bonded together with a double bond.

As you can see, this isn't balanced, but don't worry, we'll talk about that in another lesson.

Let's check to see if you've understood what I've said so far.

Which of these are the products of photosynthesis? A, carbon dioxide.

B, glucose.

C, oxygen.

Or D, water.

Take five seconds now, or if that's not enough time, click pause and click play when you're ready to see the answers.

Let's take a look at the answers.

Which are the products of photosynthesis? B, glucose, and C, oxygen.

Great job if you got those right.

Carbon dioxide and water are wrong because those are the reactants.

In this section, we're going to look at glucose and what it is and why it's so important.

So glucose is a type of sugar, which is a simple carbohydrate.

The glucose made by photosynthesis is used by producers in various ways.

Some is used as a fuel for cellular respiration to transfer energy for life processes, such as active transport.

Some is used to build biomass for growth and repair.

And biomass is all the biological material that makes up the cells and tissues of an organism.

So, my biomass or our biomass is stuff like our bones and our muscles and our cell membranes and the materials that make up all the different parts of our cells, our organs, and our organ systems. All the biomass of a producer is made from glucose.

Some of this glucose is turned into larger carbohydrates, such as starch for storage.

For example, potatoes are a type of storage structure that some plants use, what potato plants use.

They're called a tuber.

And the potato is the starch storage for the potato plant.

Glucose also gets turned into larger carbohydrates, such as cellulose and lignin, which is used to build cell walls.

Glucose can also be turned into lipids, such as fats and oils.

And this is used for storage, for energy storage, and also to build cell membranes.

And some glucose is combined with nitrogen, which is found from nitrate mineral ions which the plant gains from the soil.

So this carbon from the glucose is combined with the nitrogen from nitrate mineral ions to make amino acids.

And those amino acids bond together to make proteins, which include things like enzymes.

It can be really easy to make mistakes when you're talking about photosynthesis.

And a lot of that comes from just how different the way that plants gain food to the way that we gain food is.

And when we try and make analogies and metaphors between the way that I eat and the way I gain food to the way that plants gain their food source, it doesn't really work.

They're too different really to compare helpfully.

Let's talk about what the word food actually means and maybe that will help us out.

So in science, the word food means something that an organism uses as both a source of materials for growing and repairing.

And, so it has to do both of these things, and it also has to provide a source of energy.

The things that producers take in from their surroundings are not food because each thing is only used in one of these ways, not both.

So if we look at this visual summary of the inputs and outputs of photosynthesis, so we have light energy and carbon dioxide and water, which are all going into the plant in some way, and none of those things count as food in their own right.

And the reason for this is they don't.

So let's look at each one individually.

So light is a source of energy, but it's not a source of materials for growth and repair.

Like I said, light's not made of atoms. We can't make proteins.

We can't make fats out of light because it's not a physical substance.

If we look at carbon dioxide and water, well, we can use the carbon and the oxygen in carbon dioxide and the hydrogen and the oxygen in water in order to make materials that will help grow and repair the plant.

But none of those things are a source of energy for the plant.

And similarly, mineral ions.

You might see in supermarkets, little packets of things, or in garden centres, little packets called plant food.

And what those contain are mineral ions.

But are mineral ions food? I said in a previous slide that mineral ions such as nitrates get turned into, well, the nitrogen gets taken out of those and that gets turned into amino acids.

So that is a source of materials for growth and repair, but it's not a source of energy.

The glucose made by photosynthesis is used in both of these ways.

Glucose is a source of materials for growth and repair and it's also a source of energy because it's used as a fuel in cellular respiration.

And so the glucose is the food a producer needs.

The biomass of a plant is all the biological material that makes up its cells and tissues.

Most of the mass of this biological material is carbon atoms. Who correctly explains where this carbon comes from? Is it Andeep? "It all comes from carbon dioxide in the air." Or Izzy? "Air doesn't feel heavy, so at least some of the carbon must come from the soil." Or is it Laura? "Some of the carbon atoms come from molecules of water." Take five seconds, or if you want some more time to think about that, click pause and then click play when you're ready to see the answers.

Good luck.

Let's look at the correct answer.

It is Andeep.

"It all comes from carbon dioxide in the air." Let's have a look at the other answers.

So Izzy says, "Air doesn't feel heavy, so at least some of the carbon must come from the soil." And this is a really common idea that people have, but it is incorrect.

And I think the reason this idea comes about is because, like Izzy says, air doesn't feel heavy, but soil does feel heavy.

Thought about it in that terms, trees are solid, soil is solid, so something from the soil must be going into the trees to make it solid.

Plants are a completely different type of organism and they contain very special enzymes that allow them to take the carbon from carbon dioxide and turn it into something solid, such as glucose turning into cellulose.

We can't do that.

Humans can't do that.

We can't take the carbon out of carbon dioxide.

We don't have the enzymes or any of the things necessary to do that.

Let's look at what Laura has to say.

"Some of the carbon atoms come from molecules of water." Well, let's think back to what water is made of.

Water is H2O.

H, hydrogen.

O, oxygen.

So there's no carbon in pure water.

So Laura can't be right either.

As difficult as it can be to wrap your head around, Andeep is correct.

All of the carbon in a plant comes from carbon dioxide from the air.

Isn't that amazing? Plants are so, so interesting and so special.

Well done if you got that right.

This is the first practise task of today's lesson.

Number one, describe three ways in which the glucose made by photosynthesis is used to build biomass.

And number two, explain why the glucose made by photosynthesis is all the food a producer needs.

You'll need to pause the video now to give yourself enough time to answer that and then click play when you're ready to see the answers.

Good luck.

Let's look at the answers.

Okay, number one.

Describe three ways in which the glucose made by photosynthesis is used to build biomass.

Some is used to make larger carbohydrates, such as starch for storage, and cellulose and lignin to build cell walls.

Some is used to make lipids, which are fats and oils, for storage and to build cell membranes.

And some is combined with nitrogen, from nitrate mineral ions, to make amino acids and proteins, including enzymes.

Number two.

Explain why the glucose made by photosynthesis is all the food a producer needs.

The glucose made by photosynthesis is used both as a source of materials to make biomass, carbohydrates, lipids, and proteins, for growth and repair, and it's also used as a source of energy.

Because the glucose is used in both of these ways, producers do not need any other food.

Other things taken in by a producer from its surroundings, such as light, carbon dioxide, water, and mineral ions, are not food because each thing is only used in one of these ways, not in both.

Great job if you got those right.

On a sunny day, a large oak tree can make 90 kilogrammes of glucose by photosynthesis.

That's the mass of an adult human.

Explain why the tree is not 90 kilogrammes heavier at the end of the day.

In your answer, include ideas about how the glucose from photosynthesis is used by the tree.

Again, you'll need to pause the video now to give yourself enough time to have a go at that, and click play when you're ready to see the answers.

Good luck.

Okay, let's look at the answer.

Some of the glucose made by photosynthesis is used to build biomass, so the tree will gain some mass.

But some of the glucose made by photosynthesis is used as a fuel for cellular respiration to transfer energy for life processes.

Cellular respiration produces carbon dioxide as a waste product, which is released back into the atmosphere.

So this carbon is lost.

This means the tree's mass does not increase by 90 kilogrammes.

Great job if you got that right.

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

We've talked about what a producer is and what photosynthesis is.

Now we're going to introduce the term consumers and talk about producers and consumers.

So a producer is one that makes its own food through photosynthesis.

But some living organisms cannot photosynthesize, so cannot make their own food.

But like all living organisms, they do still need food.

They do still need food as a source of energy and a source of materials to make biomass for growth and repair.

These organisms are consumers that get food by eating producers or other consumers.

All animals are consumers.

So this includes invertebrates, such as jellyfish, worms, arachnids, and insects.

They all eat other consumers or producers.

And also, this includes all vertebrates, such as amphibians, fish, birds, reptiles, and mammals, which includes humans.

Let's check to see if you understood that.

The photograph shows a chipmunk, which is a mammal, eating a sunflower, which is a plant.

Which of them is a consumer? A, both.

B, just the chipmunk.

C, just the sunflower.

D, neither.

Take five seconds, or if that's not enough time, click pause and click play when you're ready to see the answer.

Let's look at the answer.

It is B, just the chipmunk.

The chipmunk is eating the sunflower.

So the chipmunk is a consumer.

A sunflower is a type of plant.

So it's a producer.

It photosynthesizes.

It can't be a consumer.

Great job if you got that right.

The biomass of all living organisms is made mostly of carbon atoms. Producers get carbon atoms from carbon dioxide in the atmosphere.

Through photosynthesis, they convert it into glucose, which they use to build biomass.

Consumers cannot use carbon dioxide from the environment to make biomass.

They don't have the special enzymes that plants have that are necessary to do this.

Similarly, consumers cannot absorb nitrogen from the environment to make amino acids and proteins.

Consumers can only get carbon and nitrogen by eating the biomass of producers, or of other consumers that ate producers.

For an example of that statement I've got in the brackets is a bird that eats a ladybird.

So the bird and the ladybird would both be consumers.

But the ladybird gained its carbon and nitrogen by eating leaves, which are from plants, which are producers.

Every food chain starts with a producer that makes all the biomass that is transferred along the chain when organisms are eaten.

That's what this food chain here is showing.

We start with grass, a producer.

That arrow represents the biomass that is being transferred from the grass to the cow, a consumer.

And then the cow's biomass is being transferred from the cow to the human when a human eats that cow.

So the arrows here are showing the transfer of biomass from producer to consumer to some other consumers.

Let's check to see if that made sense.

Which organisms in the food chain are consumers? A, grass.

B, cow.

C, human.

Take five seconds, or if that's not enough time, click pause and then click play when you're ready to see the answers.

Let's look at the answers.

Which organisms in the food chain are consumers? B, the cow, because it eats the grass.

And C, the human.

He eats the cow.

Great job if you got that right.

This is the second practise task of today's lesson.

Here, we have a food chain.

We have a rose plant, aphid, and ladybird.

Andeep says, "The arrow shows what eats what." Izzy says, "The arrow means 'eats.

' " And Laura says, "The arrows show the transfer of biomass." Here are the questions.

Number one, who best explains what the arrow shows in the food chain diagram? Explain your answer.

And number two, explain why every food chain starts with a producer.

Take five seconds.

Well, actually, no.

Don't take five seconds.

That's not enough time.

You'll need to pause the video now in order to give yourself enough time to think about those questions and to write down your answer and then click play when you're ready to see the answers.

Good luck.

Let's look at the answers.

Who best explains the arrows? Who best explains what the arrows show in the food chain diagram? Explain your answer.

Andeep is correct, but is not being specific enough.

Izzy has read the arrows the wrong way around.

The arrows mean "is eaten by" or "is food for." Laura is correct.

Predators eat the biomass of their prey.

Number two, explain why every food chain starts with a producer.

Producers make biomass by photosynthesis, but consumers cannot.

All the biomass that moves along the food chain was made by producers.

Great job if you got those right.

We've now completed the first two parts of today's lesson.

We've talked about producers and photosynthesis and producers and consumers.

Now we're going to talk about the relationship between producers and the atmosphere.

So in this part of the lesson, we're going to focus on the gases that are involved in photosynthesis.

Carbon dioxide and oxygen.

During photosynthesis, producers take in carbon dioxide from the atmosphere.

So here we have carbon dioxide gas diffusing into the tiny holes on the bottom of a leaf, and they released waste oxygen into the atmosphere.

So here we have oxygen gas diffusing out of a leaf.

Evidence from rocks and fossils suggest that photosynthesis first evolved approximately 3.

5 billion years ago.

Scientists think that before this, Earth's atmosphere was similar to the atmosphere on Mars today, where there are no producers as far as we know.

So here's the composition of the atmosphere on Mars.

Mostly carbon dioxide.

Whereas this is the composition of the atmosphere on Earth.

Photosynthesis in producers has changed the percentage of carbon dioxide and oxygen in the Earth's atmosphere.

So we have far, far, far less carbon dioxide because this carbon dioxide is diffusing into leaves and then being turned into glucose.

And we have much more oxygen because this oxygen is being released as a waste product of photosynthesis.

Producers and consumers need oxygen from the atmosphere for aerobic cellular respiration.

Without photosynthesis in producers, there would be not enough oxygen in the atmosphere for cellular respiration to take place.

So here again, we have oxygen gas diffusing out of a leaf because it's a byproduct of photosynthesis.

So this means there would not be enough oxygen, so without photosynthesis, there would not be enough oxygen to support life on Earth.

And so consumers depend upon photosynthesis in producers for both the food and oxygen that they need to stay alive.

Let's check to see if that made sense.

Which statements are true? A, photosynthesis adds carbon dioxide to the atmosphere.

B, photosynthesis adds oxygen to the atmosphere.

C, photosynthesis removes carbon from the atmosphere.

Or D, photosynthesis removes oxygen from the atmosphere.

Take five seconds or if that's not enough time and you want some more time to think, click pause and then click play when you're ready to see the answers.

Let's look at the answers.

Which statements are true? B is true.

Photosynthesis adds oxygen to the atmosphere.

And C is true.

Photosynthesis removes carbon dioxide from the atmosphere.

Great job if you got those right.

This is the final practise task of today's lesson.

Question one, explain why consumers depend upon photosynthesis in producers.

And number two, imagine that a natural disaster has filled Earth's atmosphere with smoke and dust.

This blocks out all the light.

Explain what would happen to producers and consumers without light.

You'll need to pause the video now to give yourself enough time to think about those questions and to write down your answer.

Now click play when you're ready to move on with the lesson and to see the answers.

Good luck.

Let's look at the answers.

Number one, explain why consumers depend upon photosynthesis in producers.

Photosynthesis in producers makes the food that consumers need as a source of materials for growth and repair.

It also makes the oxygen that consumers need for aerobic cellular respiration to transfer energy for life processes.

Number two, imagine that a natural disaster has filled the Earth's atmosphere with smoke and dust.

This blocks out all the light.

Explain what would happen to producers and consumers without light.

So without light, photosynthesis would not occur.

So producers could not make any new glucose, food.

Producers could use stored starch as a source of food for a while, but would then die out.

Consumers would also die out, as they depend on producers for the food and oxygen they need to survive.

Amazing work today.

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

Producers use photosynthesis to make their own food in the form of glucose, which is a simple carbohydrate.

Consumers can only get food by eating producers or other consumers.

Producers are the source of food for food chains.

Producers and consumers use the carbohydrate from photosynthesis to make biomass for growth and repair, and as a fuel for cellular respiration.

Consumers cannot use carbon and nitrogen from the environment to make biomass.

They can only get them by eating producers.

Consumers also depend upon producers to add oxygen to the atmosphere, which they use for aerobic cellular respiration.

Again, really great job on today's lesson.

I hope you enjoyed the lesson and I hope to see you again really soon for our next lesson.