Lesson video

Hello, and welcome to today's lesson from the unit, "Reproduction in Plants".

The title of today's lesson is "Pollination and Fertilisation", and we're gonna be looking at these two really important processes that are part of reproduction of plants.

How the pollen, the male gamete, is transferred to the female part of the plant, and how that pollen is using the fertilisation of the female gamete to form a zygote.

My name's Mrs. Barnard and I'm going to be taking you through today's lesson.

So by the end of today's lesson, you should be able to describe the processes of pollination and fertilisation in flowering plants.

So we've got some keywords today.

So some of the words we're gonna be using in today's lesson you will have used before in the structure of the flower, but we've got a few different ones today to highlight to you.

So I'll put the definitions up in a moment.

So if you want to copy them down, you can pause the video to do so.

But otherwise, we'll be going through them as part of the activities in today's lesson.

So our keywords are ovary, pollination, style, fertilisation, and stamen.

Our lesson today is in two parts.

The first part is the process of pollination, so how the pollen gets from the male part of the flower to the female part, and the second part is fertilisation, so how a zygote is formed from the two gametes of a flowering plant, the pollen and the ova.

So let's get started with the first part of today's lesson, which is pollination.

So, the flower is the reproductive system of a plant.

And we've talked about this in previous lessons, and you may have learned about it before in school, but how many organs of this system can you recall? So you might want to talk to the person next to you.

Let's see how many you can come up with.

Okay, let's see how you got on then.

So we've got the anther, we've got the stamen, which is the male part, so that includes the filament and the anther, then we've got the ovary and the ovules there at the bottom.

And then we've got the stigma.

So the stigma and the ovary and the ovules make up the female part of the plant.

And then we've got the petal that attracts our pollinators.

So did you get all of those? Let's see.

So, pollination is a process of transferring pollen grains from a male anther to the female stigma.

So these are the two parts of the reproductive system that we're interested in in the process of pollination.

So the pollen carries the male gametes of the plant, and each pollen grain carries half of the DNA that's gonna be required to make the seed.

The other half of the DNA will come from the female gamete, because this is is sexual reproduction.

So if we have a little zoom in here on the anther, we can see it's part of the stamen, and we can see the pollen grains that are made there.

And that pollen there is deposited on the stigma, which is the female part of the plant.

And when the pollen is deposited on the stigma, that means that the male DNA can be used in sexual reproduction.

So time for a quick check.

Choose the female parts of the flower from the list below.

So pause the video while you do this.

Okay, how did you get on then? So the female parts are the stigma and the ovary, okay? The stamen is formed from the anther and the filament, which are the male part of the flower.

So pollination is the first stage in the process of sexual reproduction.

And the pollen from a flower can be transferred to its own stigma.

So you've got the anther there that's part the stamen, and the pollen can transfer onto its own stigma within the same flower.

And this is called self-pollination.

Also, the pollen from a flower on one plant can be transferred to the stigma of another plant.

Now, that plant does have to be of the same species in order for their gametes to be able to fuse together to form a zygote, but they can be transferred from one flower to another.

Now, there's different methods by which this pollen can be transferred, and this is called cross-pollination.

And we'll talk in a minute about the different ways the pollen is transferred.

But cross-pollination is when we have the pollen from one flower being transferred to the stigma of another.

So cross-pollination increases variation, because rather the DNA coming from the male and female parts of the same flower, they come from the male and female parts of different flowers.

So that's gonna give you more variation within your species.

And here's an example here of different variation that we've got in geraniums in the colours of their petals.

So let's have a quick check here.

So cross-pollination is the process of pollen moving from the anther to the stigma.

So I want you to decide whether this is true or false.

And once you've decided, which of the statements below do you think support your choice? Okay, so you've got cross-pollination is the transfer of pollen from one flower to another flower.

And we've got cross-pollination is the transfer of pollen from the flower of one plant to the flower of another plant of the same species.

So pause while you decide.

Okay, so the correct answer is false.

Cross-pollination is the process of pollen moving from the anther to the stigma, and the reason that that is false is because it is specifically the transfer of pollen from the flower of one plant to the flower of another plant of the same species.

And that's why we get variation, because we get DNA from different plants that's gonna come together in the offspring.

But if you've got that right, then well done.

So pollen grains are very small.

You can sometimes see them as a fine mist, particularly if they're clumped together, but they can be moved very easily from one flower to another in cross-pollination.

And the ways that they can be moved is that they can either be moved by an animal, so on the surface of an animal, or within an animal.

And this is something we'll look at in later lessons, or they can be moved on the wind, or they can be moved by water.

And often, flowers are specifically designed to allow their pollen to be transferred by one of those methods.

So it's always nice to see what the real thing looks like.

So this is a pollen grain as looked at down a microscope.

And you can see it is very, very small.

So a millimetre is the smallest measurement on your standard ruler that you'll have in your pencil case.

So this is 0.

07 of a millimetre.

So very, very small.

So when you see pollen, it tends to be in little clumps together.

So here we've got, on this image, we've got pollen carried by the wind or water, and we've got pollen carried by animals, such as bees.

So 80% of pollination is carried out by animals, and this includes bees and flies, wasps, butterflies, and beetles, but the majority is performed by bees.

Now, when you say animals, most people think about mammals, but insects are animals too.

And so we've got a lot of different types of insects there.

So it's not just bees that do the pollination.

So we've got flies in there, wasps, butterflies, and beetles.

And here's a few images to show you them doing their job.

And it is a vital job because it maintains our food supply, okay? Because 70% of our crops, so the food that we eat, is actually pollinated by bees.

So pollination is really, really important and us understanding it and making sure that those insects, particularly bees, are around in order for pollination to take place is really important.

So, from these images below, which of the two images are pollinators? So pause while you decide.

Okay, so we've got a beetle, an earthworm, and a butterfly.

And the correct answers are the pollinators are a beetle and a butterfly.

So this beetle is called a rose chafer, so it particularly pollinates roses.

And then we've got a butterfly here.

Now, an earthworm is in the ground, so it's not usually very close to pollen, so its job is not to pollinate.

Okay, so time for a quick practise task.

So Oak pupils here are discussing the importance of bees.

So Izzy says bees help with cross-pollination, and Jacob says bees transfer pollen from the anther to the stigma.

And here's a little picture here of all of the different parts of the flower to help you with your task.

So Izzy and Jacob have made some correct statements.

So what I would like you to do is to write an explanation for the importance of bees.

Now, include their ideas in your answer, but add your own detail and keywords, and you can see there's some keywords there for you to include.

So it'll take you a little bit of time to do this extended writing.

So check back when you were ready and we'll have a look at your answer.

Right then, let's see how we got on with that.

So Izzy and Jacob have made some correct statements.

So Izzy said bees help with cross-pollination and Jacob said bees transfer pollen from the anther to the stigma.

But what you are gonna do is write a more detailed explanation for the importance of the role of bees.

And this is what it could look like or it could include.

So bees transfer pollen from the anther to the stigma either within the same flower or from a different plant.

If pollen is transferred from a different plant, it is called cross-pollination.

Pollination is an essential part of reproduction, as the pollen carries the male gamete.

Cross-pollination increases variation in the species as DNA is transferred from one plant to another.

So if you've got some of those scientific ideas in your answer, then well done.

It's a good opportunity for you to be able to show what you really understand about this process.

So, time to move on to the second part of our lesson, and that is fertilisation.

A little recap here on sexual reproduction.

A pollen grain and an ovum each carry half of the genetic information that is required to make a seed.

The genetic information is coded in the DNA, and that is packaged into chromosomes that are stored in the nuclei of those cells.

It's stored in the nucleus of each gamete.

So we've got an ovum here and we've got a pollen.

And then we can see that in that nucleus, we've got the chromosomes, and the chromosomes are bundled up DNA, and there's our DNA.

So that's where our genetic code is stored.

So both of those gametes are contributing their genetic code to the next offspring.

So what pollination does, as we've just learned in the previous part of the lesson, is it brings the male gamete, the pollen, of a plan to the stigma of the female reproductive organs.

And what happens is that that gives them the nuclei of the pollen and the ovum the opportunity to fuse together.

And that process is called fertilisation.

Now, this is the same process that happens in humans.

So you may have learned about this before.

So when the sperm and the egg fuse together in the fallopian tubes, we call that fertilisation.

And then we form an embryo.

And that's the same here.

So we've got the gametes, so we've got the pollen and the ovum, and they've got half a set of chromosomes each, and then they fuse together and then the nuclei will fuse, and then the zygote that is produced will have a full set of chromosomes.

So let's have a quick check on your understanding.

So pollination is required for sexual reproduction to take place.

Do you think that's true or do you think it's false? And once you've decided whether it's true or false, which of the statements below do you think best justifies your choice? So is it pollination transfers pollen from the stigma to the anther of a flower, or is it pollination brings the male gamete with half of the DNA to the stigma? So pause up while you make your choice.

Okay, so the correct answer is true, pollination is required for sexual reproduction to take place.

And the best justification for that is the second one, because pollination brings the male gamete with half of the DNA to the stigma, and that's why we get sexual reproduction, which is where two plants will contribute their DNA.

So the process of pollination and fertilisation, which are two separate processes, sometimes people get those mixed up, enable the plant to reproduce.

So we've got our pollen to start with and our pollen will land on the stigma.

Now, we learned in the previous parts of the lesson that this could be by self-pollination, so it could be pollen from the same flower, or by cross-pollination.

So that pollen could have come from another plant, so the anther of another plant.

And when it lands on the stigma, a pollen tube will form and it will move down the style.

And what's gonna happen is the male gamete from the pollen are going to move down that pollen tube all the way down the style, and they're moving towards the ovary there at the base.

So the male gametes will continue down the pollen tube until they reach the ovary.

And in the ovary, we've got the ovules and we've got the ova, or an ovum, which one gamete will fertilise.

So there our pollen tube is extended down all the way to the ovary.

And there the male gamete will enter the ovary.

So once the male gamete enters the ovary, it will fuse with the ovum to produce a zygote with a complete set of chromosomes.

And again, these keywords are the same as in human reproduction.

Our gametes use the nuclei fuse in fertilisation to form a zygote.

So we've got our ovary there and we've got the male gamete fusing with an ovum to form a zygote.

So, from that point forward, the zygote is going to develop into a seed, 'cause the zygote is just the first stage where there's two nuclei fuse.

Now, the development will be slightly different in a plant to what it is in a human, but it goes through some similar stages so that it has the same key terms. So we start with our zygote, and then we move to our embryo, and instead of a foetus, we move to our seed.

So those are the stages.

So the seed is then released, so it goes to the ground and it's carried in different methods to somewhere else where it will be able to grow.

And we'll cover that in later lessons on seed dispersal.

And that seedling will grow into a new plant, and that new plant will resemble its parents, because it's been made by sexual reproduction and it has half of the same DNA as each parent.

And the new plan is the offspring of the plants that provided the pollen and the ovum, and therefore reproduction is complete.

So we go from seed to seedling to plant.

Okay, so time for a little bit of a check.

So what I'd like you to do is to put these stages of plant reproduction into the correct order.

So we've got the pollen tube forms down the style, a male gamete and an ovum fuse to form a zygote, pollen is to deposited on the stigma, a male gametes move down the tube to the ovary.

So decide what order those go in.

Pause the video and then we'll check back and see how you've got on.

Okay, let's see how you got on then.

So the first one is that pollen is deposited on the stigma.

The second one is that the pollen tube forms down the style.

The third one is that the male gametes move down the tube to the ovary, and then the fourth one is that the male gamete and the ovum fuse to form a zygote.

So if you've got those in the correct order, then that's brilliant.

Well done.

And let's move on.

So the next check is to match the process to the correct image.

So these three processes are words that often get confused when people talk about plants and plant reproduction.

So we've got to make sure that we know what the difference between them is.

So we've got pollination, fertilisation, and germination.

So which process matches which image? So pause while you make your decision.

Okay, so let's see how you got on.

So pollination is where the pollen is deposited on the stigma.

So that's b, you can see the pollen at the top of the stigma there.

And then fertilisation, that is when the two gametes fuse.

So that takes place in the ovary, and that's when a zygote is formed.

So that's picture c.

And finally, germination is that when a seed develops a stem and leaves and roots, okay, it starts to become a new plant.

So that is a.

So if you've got those right, that's really good, well done.

So if you know your processes, that's gonna make it much easier to go onto our next practise task.

So our practise task now is as follows.

These are images of pollination and fertilisation and they have already been put into the correct order for you, so you don't have to worry about that.

So what you need to do is you need to add keywords and descriptions of the processes involved at each stage.

Now, you might want to go back to your keywords, or look through some of the slides again to ensure that you've got all the information that you need in order to do this, or you might feel confident to just go ahead and do it straight away.

Either way, this is gonna take you a little bit of time, so pause the video while you do it and then we'll come back and we'll see how you got on after.

Okay, let's see how you got on with that then.

So, for the first image, number one, we should say that the pollen lands, or is deposited on the stigma by wind, or water, or an insect.

Number two, a pollen tube forms and the male gametes move down the style towards the ovary.

Number three, the nuclei of a male gamete and an ovum fuse together to form a zygote in the ovary.

Stage number four, the zygote develops into an embryo and then on into a seed.

And this goes on to germinate to form a new plant.

So there's lots of keywords of structures and processes in there.

So if you've got all those into your answer, then that's brilliant.

Well done.

And that brings us to the end of today's lesson.

So let's look at the summary.

So pollination is the transfer of pollen carrying male gametes from the anther to the female stigma.

The anther is part of the male reproductive system, the stamen.

There are two types of pollination, self-pollination and cross-pollination, where pollen is carried by wind, water, or insects.

Pollination and pollinators are essential for the reproduction of plants, and therefore human food supply.

Male gametes from pollen move from the stigma down the style to the ovary in a pollen tube.

Fertilisation is the fusion of the nuclei from the male and the female, ova, gametes, and this takes place in the ovary and forms a seed.

So lots of new words in today's lesson, but well done for your work.