Lesson video

Welcome to lesson number four in the unit biodiversity.

My name's Mr. Jarvis, and I'm going to be going through the lesson with you today.

Today's lesson is all about plants and how they're adapted for their environment.

By the end of today's lesson, you should be able to describe how some plants are adapted to help them to survive, and how environmental conditions affect plant biodiversity both positively and negatively.

There are four key words to today's lesson.

They are biodiversity, adaptation, extinction, and conservation.

Coming up on the screen now, the definitions of those words.

I'll pause for a few seconds to let you read those for yourself, or you can also pause the video and then press Play when you're ready to start.

Today's lesson is going to be broken down into three parts.

First of all, we're going to look at biodiversity and plants.

We'll then move on to talk about different adaptations that we can see in plants.

And, finally, we'll look at the impact on plants of a changing habitat.

So if you're ready, let's get started with our first part to today's lesson, which is all about biodiversity and plants.

Plants are important in habitats.

This is because they provide the food for organisms in food chains.

Plants are producers.

Producers make their own food, but they don't just make food for themselves.

They make the food that gets eaten by all of the organisms in food chains.

They also provide shelter for organisms, for example, these bats sheltering in a tree.

And they also provide places for organisms to reproduce.

For example, these birds nests that have been built in a tree.

The interdependence between plants and animals in a habitat are important for humans.

This is because plants provide the food that humans eat, and they also provide some of the medicines that humans rely on.

For example, there's a drug that's obtained from a foxglove that's used in medicine to help with a heart condition.

Plants also help humans by helping to clean air and water.

Plants help to remove pollutants from the air or from the water, and they also help to protect humans from some natural disasters.

For example, mangroves and coral reefs are habitats that protect humans from floods.

Biodiversity is the range of different living organisms that live in a place.

Bio means relating to living things, and diversity means having many different things in one place.

So the higher the number of different organisms that live in a place, the greater the place's biodiversity.

It's not just about the number of organisms; it's about the range of different organisms that live somewhere.

So let's check what you know so far.

True or false? Biodiversity is the number of different organisms that live in a habitat.

Is that true or false? And then justify your answer.

Is it because, A, a habitat has a large biodiversity if it has a large range of different species, or B, a habitat has a large biodiversity if it has a large number of organisms. I'll give you five seconds and then we'll check your answer.

The answer to the question is false.

Biodiversity is not the number of different organisms living in a habitat, and that's because a habitat has a large biodiversity if it has a large range of different species.

Well done if you got that right.

Different habitats have different levels of biodiversity.

Many warmer and wetter habitats have the greatest biodiversity, and these habitats are often found between the Tropics of Cancer and Capricorn.

Between the purple dotted lines on the picture of the map at the bottom of the screen.

Examples of habitats with high biodiversity that are found between the Tropics of Cancer and Capricorn include tropical rainforests, coral reefs, and mangrove swamps.

Biodiversity is lower in more extreme habitats such as tundra and tundra is typified by frozen ground.

And that's because habitats like tundra and Arctic habitats require organisms to have very specialised adaptations in order to survive.

Remember, an adaptation is a feature that helps an organism to survive in that particular place.

Tundra plants have adaptations which result in them being low growing, adapted to living in cold temperatures and having shallow root systems due to the lack of soil.

Maintaining a rich biodiversity of plants is important to all living things.

Humans have described around 400,000 different plant species.

And new species are being discovered in many tropical rainforests.

For example, there was a new species of myrtle similar to the one in the picture that was discovered in Bolivia in 2023.

However, scientists estimate that over 600 plant species have become extinct in the last 250 years.

And many plant extinctions are due to agriculture, land change for human habitation, and climate change.

Remember, when an organism becomes extinct, it's lost forever.

So let's check what we've done so far.

The higher the biodiversity in a habitat, A, the greater the number of plant species that live there; B, the greater number of species that live there; or C, the greater number of animal species that live there.

What do you think is the right answer? I'll give you five seconds and then we'll check.

The correct answer is B.

The higher the biodiversity in a habitat, the greater the number of species that live there.

So let's do our first task of today's lesson.

The pupils are discussing biodiversity of plants in different habitats in the world.

Who do you think is right? And write an explanation for your answer.

So Aisha says, "Plant biodiversity is highest at A." Sam says, "More species of plant live at B.

Biodiversity is high there." And Sofia says, "Habitats at C have the greatest plant biodiversity." Who do you think is right? And write an explanation for your answer.

You'll need to pause the video at this point.

Once you've written your answer, press Play and we'll check to see whether you're right.

So, how did you get on? Who was right and why? Well, the correct answer was Aisha.

Plant biodiversity is highest at A.

Here's the reason.

Point A is between the Tropic of Cancer and the Tropic of Capricorn, and that means that the climate here is warm and wet, and they're ideal conditions for plants to grow.

Plants living within those areas are less likely to need specialised adaptations to cope with extreme environments.

Well done if you got those points in your answer.

That brings us to the second part of today's lesson, and that's all about adaptations of plants.

So if you're ready, let's move on.

Adaptations are features which help organisms to survive.

And most plant adaptations help with one or more of the following: to get more sunlight, to get water and nutrients from the soil, to avoid losing too much water from their leaves, to avoid being eaten through having spikes and spines, and to reproduce and disperse their seeds.

So let's look at some adaptations that plants have.

First of all, let's look at adaptations in plant roots.

Plants use their roots to get water and nutrients from the soil.

And plants will have different types of roots depending on the amount of water that's found within their habitat.

So here we have a picture of a succulent.

The succulent is found in a desert.

Now, deserts are really extreme places in terms of temperature.

They can be really hot in the daytime and really cold at night, but the main feature of deserts are that they're dry places and plants from dry places such as deserts and seen in this succulent are that they have really fine roots at the surface.

And that means at night when it's cold and there's some juice, some condensation that falls onto the surface of the soil, the plant is able to take that water in.

They've also got long, thick roots and they grow down deep into the soil to tap on any water that's deep below the surface.

Plant leaves have adaptations, too.

They have adaptations to get sunlight to help them make the food that they need.

Plants that live in darker places, for example, forest floor habitats, have really big leaves.

And you can see this Gunnera plant lives in a naturally damp and shady area in South America.

You can see how big the leaves are.

Plants also lose water from their leaves.

Plants that live in hot places have leaves that store water, are waxy or reduced to spines or spikes, and that helps 'em to reduce their water loss.

The plants often use their stem to take in sunlight, and you can see here that you've got some waxy leaves of succulents, but also that you've got fleshy stems that are green, and that's because they use those stems to help them make the food that they need from the sunlight.

So let's check to see how well you've understood that last section.

Why are some plants adapted to have waxy leaves? Is it, A, to reduce water loss; B, to avoid being eaten; or C, to trap insects? I'll give you five seconds and then we'll check your answer.

The correct answer is A, to help them reduce water loss.

Well done if you got that right.

Here's another one.

Why are some plants adapted to have large leaves? Is it to reduce water loss; to increase absorption of sunlight; or to gain water? Again, five seconds and then we'll check to see whether you got the answer right.

The answer to this one is B, to increase absorption of sunlight.

Well done if you got that one right.

Plants also have adaptations to prevent them from being eaten.

One way is through the production of spines and thorns.

Here, we have two pictures.

One of a cactus where its leaves are adapted into spines to prevent consumers from eating the cactus, and a rose that has thorns on its stem, this means that it's difficult for consumers to eat them.

Another method and another adaptation that plants use is the production of chemicals.

These chemicals either make the taste of the plant unpleasant or they are sticky and make it difficult for animals to eat them.

There are some plants with specialised adaptations.

For example, there are plants that live in soils where nutrients are low, and these plants have adaptations to catch and digest animals to get the nutrients that they need.

Carnivorous plants don't eat organisms; they just catch the organisms and break down the bodies so the nutrients drip into the soil and then the plant's roots can take up these nutrients.

Plants also have behavioural adaptations.

These help the plant to survive, too.

Here are two examples.

First of all, leaves grow towards the light.

This is important because plants need light to make their own food.

The picture shows some cress seeds that are growing towards the light on a window sill.

There's a video here that you can watch too.

This shows how a plant responds to light during the course of a day.

The second example is the roots.

The roots always grow downwards.

And there are two advantages to this.

First of all, the roots grow downwards because that's where they find the water that they need to survive.

And secondly, growing downwards with a network of roots helps to anchor the plant into the soil.

Let's move to a check.

Why do roots grow downwards? Is it, A, to anchor the plant in the soil; B, to avoid sunlight; or C to get water? I'll give you five seconds and then we'll check your answer.

So the correct answers are, A, to anchor this plant in the soil and C, to get water.

Well done if you got both of those.

Here's another.

Which of the following adaptations could help to protect plants against being eaten and against losing water? Is it, A, to have deep roots; B, to have sharp thorns or spikes; or C, to make unpleasant tasting chemicals? Again, five seconds and we'll check your answer.

The correct answer here is B, to have sharp thorns or spikes.

Let's move to a practise task.

There are two questions here.

First of all, I'd like you to match the adaptations to the correct statement.

So here are your adaptations.

They're waxy leaves, thorns and spines, sticky leaves, roots grow downwards, and chemicals produced by leaves.

And how does that help the plant? Here are your statements: To trap organisms, to make leaves taste bad to consumers, to help reduce water loss, towards sources of water, and makes leaves difficult to eat.

Match the adaptation to the other part of the statement.

And then the second part is that water lilies naturally grow in fast-flowing streams. Their roots grow in mud at the bottom of those streams. What adaptations might water lilies have to help them to survive in these fast-flowing streams? You'll need to pause the video at this point so that you can answer both of those questions.

And when you've answered them, press Play and we'll check your answers.

Good luck.

So how did you do? Let's see, first of all, with the matching the adaptations to the statements.

Waxy leaves help to reduce water loss.

Thorns and spines make leaves difficult to eat.

Sticky leaves trap organisms. Roots growing downwards towards sources of water, and chemicals produced by leaves make the leaves taste bad to consumers.

Well done if you matched all of those adaptations with the correct statement.

The second part of this task was what adaptations might water lilies have to help 'em survive in fast-flowing streams? You might have had long roots to anchor the plant and stop it being washed away.

Long stems that are flexible to prevent being broken in the water current.

And you can see some of those long stems are in the top picture there of the water lily pads from underwater.

The long stems carry leaves to the water surface so that the plants get lots of sunlight.

And you can see that in that top picture.

Large leaves catch as much sunlight as possible.

Flowers bloom above the water so that they can be pollinated by insects, and flowers are attractive colours and scented to attract insects for pollination.

Well done if you got some or all of those answers correct.

That brings us to the final part of the lesson, and this part is all about the impact of a changing habitat.

So if you're ready, let's move on.

Habitats constantly change.

There is some natural change.

Some of this can be really significant, for example, a forest fire.

Those forest fires will temporarily reduce habitat biodiversity.

Some species do have adaptations that help them to survive natural disasters such as forest fires.

Can you think about what adaptations plants might have that might help them to survive these forest fires? I'll give you a few seconds to think.

One of the ways that plants are able to survive forest fires is by having seeds that are resistant to really high temperatures.

And in some cases, those high temperatures actually cause the seeds to germinate.

Well done if you got any answers yourself.

The human population has a significant impact on biodiversity.

The largest human impacts on plant biodiversity are around the change of land use, and in particular, deforestation.

We also have an impact through agriculture, farming crops in large fields and using lots of chemicals.

And there's also a human impact in terms of climate change.

Can you think of any reasons why humans could also clear large areas of forest that aren't covered in this slide? I'll give you a few seconds.

One of the reasons that you might have come up with is to build new houses.

We often find that humans clear large pieces of land to enable them to build new settlements.

Well done if you've got that or any other answer right.

Deforestation impacts biodiversity and the environment in lots of ways.

It causes the extinction of species, and extinction means that an organism disappears forever.

They pollute the air, they reduce the number of plants, so reducing the water that's stored within the plants, they release carbon dioxide into the atmosphere which contributes to climate change.

The soil erosion because removing the trees means that the soil isn't bound in by the roots.

Humans can do good things for the environment.

Conservation involves protecting nature and the environment.

And you often see this in conservation areas such as parks and nature reserves.

Conservation involves a balance between what humans take out of the environment and what organisms need to survive.

Conservation increases the biodiversity of plants by creating new habitats, for example, through reforestation or creating wildflower meadows.

Managing meadows help populations of some rare species, such as bee orchids, to establish.

Conservation can take place on a much smaller scale.

The biodiversity of plants can be helped in different ways.

Some examples include making borders around crop fields for wild plants to grow, or providing wild areas in parks and gardens.

So let's do a check.

Which two of the following human activities will increase plant biodiversity in a habitat? A, deforestation; B, protecting habitats as nature reserves; C, planting large fields of wheat; or D, creating wildflower areas in parks and gardens.

Remember, we are looking for two of the activities.

I'll pause for five seconds and then we'll check your answer.

So the correct answers are, B, protecting habitats as nature reserves and D, creating wildflower areas in parks and gardens.

Well done if you got those.

That brings us to our final task of the lesson.

I'd like you to write a short paragraph to explain the consequences of deforestation.

Here's a hint for you.

Think about biodiversity, particularly biodiversity of plants and why plants are important in habitats.

You'll need to pause the video, write your short paragraph, and then when you're ready, press Play and we'll check your answers.

Good luck.

So how did you do? You are asked to write a short paragraph to explain the consequences of deforestation.

Things that you might have included are: That plants define habitats, they provide food, shelter, and places for organisms to reproduce.

Deforestation kills many plants, and some of those plants could become extinct.

Plants help keep the air clean and healthy.

Forests help to store water and carbon dioxide.

Deforestation releases carbon dioxide, which contributes to climate change.

And removing roots means that soil gets washed away, and that includes the nutrients in the soil, and that means that farmers need to use fertilisers.

Well done if you got some or all of those answers right.

So that brings us to the summary of today's lesson and what we've covered in this lesson about plants being adapted for their environment.

We've talked about biodiversity being a measure of the range of different species that live in a place.

We've talked about plant biodiversity being important as plants provide food for all other organisms in food chain diagrams, and that includes humans.

We've talked about the adaptations that plants have that help them to survive in their habitat, and that includes some behavioural adaptations where leaves grow towards the light and roots grow towards the water.

We've looked at the changes to the environment and how that impacts plant biodiversity.

Habitat loss can cause the extinction of some species, and once they're extinct, they're lost forever.

And conservation by humans can help to increase plant biodiversity.

Thank you for learning with me today.

It's been great as always to teach you, and I look forward to seeing you again sometime in the near future.

Bye for now.