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Life cycles Contents Spreading seeds Will it grow? Making new plants

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Presentation on theme: "Life cycles Contents Spreading seeds Will it grow? Making new plants"— Presentation transcript:

1 Life cycles Contents Spreading seeds Will it grow? Making new plants
Circle of life Review Learning Objectives Pupils will learn: that flowering plants reproduce; that seeds can be dispersed in a variety of ways; to make careful observations of fruits and seeds, to compare them and use results to draw conclusions; that many fruits and seeds provide food for animals including humans. 1 of 34 © Boardworks Ltd 2007

2 Spreading seeds Look at these plants… How did they grow their fruits?
Image Credits Tomatoes © Andrew Allen Oranges © Allan Kilgour Apples © 2006 Jupiterimages corporation Remind pupils of earlier work on seeds and plant growth. Tell pupils that flowering plants produce fruits and seeds from their flowers, and that these grow into new plants. How did they grow their fruits? What will happen to them? Why are they important?

3 Spreading seeds

4 Spreading seeds Emphasise to pupils that plants must disperse their seeds in order to survive, and that they are dispersed so that they have the best chance of survival. Plants will compete for light, water and nutrients. Therefore it is best for the seeds to grow as far as possible from the parent plant.

5 Spreading seeds

6 Spreading seeds Plenary 6 of 34 © Boardworks Ltd 2007

7 Life cycles Contents Spreading seeds Will it grow? Making new plants
Circle of life Review Learning Objectives Pupils will learn: that flowering plants reproduce; that seeds can be dispersed in a variety of ways; to make careful observations of fruits and seeds, to compare them and use results to draw conclusions; that many fruits and seeds provide food for animals including humans. 7 of 34 © Boardworks Ltd 2007

8 Will it grow? After seeds have been dispersed they start to grow a tiny root and a tiny shoot. We call this germination. Seeds will only germinate under certain conditions… No! I refuse to start growing unless I have my own dressing room, all my favourite foods, a personal assistant... What do you think a seed really needs to germinate? Water? Light? Warmth? Let’s plan a test to find out!

9 Will it grow?

10 Will it grow? Remind pupils of the importance to put a number of seeds in each pot in order to get reliable evidence. Make sure pupils are clear that the seed in the dark germinated as well. Emphasise that light is not needed for germination, which is why we can see a shoot. Note that is looks less healthy than the other plants. This is because plants do need light for growth. Ask pupils to set up their own experiment like this one and write an account of how they set up the work. Bear in mind that some seeds can take some time to germinate, but they do not need to grow into adult plants in order for the experiment to be completed, so it can be done over a relatively short period of time.

11 Will it grow?

12 Will it grow? Plenary 12 of 34 © Boardworks Ltd 2007

13 Life cycles Contents Spreading seeds Will it grow? Making new plants
Circle of life Review Learning Objectives Pupils will learn: that insects pollinate some flowers; that plants produce flowers which have male and female organs; that seeds are formed when pollen from the male organ fertilises the ovum (female). 13 of 34 © Boardworks Ltd 2007

14 Making new plants Let’s take a closer look at the different parts of this flower. The stigma is sticky to keep hold of the pollen. The petals attract insects. The anther is the part that makes the pollen. The style supports the stigma and connects it to the ovary. The filament holds up the anther. The ovary is where the ovules, or eggs, are. The sepal leaves protect the flower before it opens.

15 Making new plants There is something special about this flower;
do you know what it is? The flower has both male and female organs! The stigma, style and ovary make up the female organ. This is called the carpel. The anther and filament make up the male organ. This is called the stamen.

16 Making new plants

17 Making new plants Although they have male and female parts, flowers need to spread their pollen around to reproduce. Insects are attracted to flowers by their bright colours, lovely smell and sweet tasting nectar. Pollen from the stamen sticks to the insects and gets carried to other flowers. Pollen brushes off the insect and onto the carpel. Image Credit Photographs courtesy of You may wish to explain to pupils that plants can pollinate themselves, though this is not desirable as genes need to be spread apart. This is called self pollination. When pollen from one plant pollinates another, this is called cross pollination. Most plants are cross pollinated. This is the process of pollination. Let’s see it in action!

18 Making new plants You may wish to remind pupils here of the other methods of pollination i.e. wind, explosion and animals.

19 Making new plants The pollen gets stuck on the stigma. Then, the pollen grows a tube down to the ovary. Fertilisation can now take place. Emphasise to pupils that a plant cannot be fertilised by any pollen; it must be of the right type. Explain to pupils that the ovule will be fertilised and then grow into a new seed.

20 Making new plants Plenary 20 of 34 © Boardworks Ltd 2007

21 Life cycles Contents Spreading seeds Will it grow? Making new plants
Circle of life Review Learning Objectives Pupils will learn: about the life cycle of flowering plants including pollination, fertilisation, seed production, seed dispersal and germination; that adults have young and that these grow into adults which in turn produce young; that human young are dependent on adults for a relatively long period; that if living things did not reproduce they would eventually become extinct. 21 of 34 © Boardworks Ltd 2007

22 Circle of life

23 Circle of life Pupils could research into the gestation periods of a number of mammals and draw a timeline to show the differences between species. If necessary briefly explain that the different gestation periods are largely due to the size of the animal.

24 Circle of life Image Credits
Elephant calf © Shankar Subramanian, India Caterpillar courtesy of Stock Xchange Swans and cygnets courtesy of Stock Xchange Mother and child courtesy of Stock Xchange

25 Circle of life It is important for animals and plants to reproduce. If they stopped reproducing, what do you think would happen? Eventually they would all die out. I’m a dodo bird. You might not have heard of me because my species died out over 300 years ago. We used to roam free on our very own island but then sailors discovered the island. They ruined our home and killed us for food. There weren’t many of us left to reproduce and so we sadly became extinct.


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