Plants and Photosynthesis– Inside the Leaf, Bees and Pollination
Lessons 5 and 6
Inside the Leaf, Bees and Pollination
Essential Knowledge for Teachers
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Transpiration is the movement of water through the plant. Plants release water molecules into the air, which cool the air
around the plant. Plants act as giant pumps, taking water up from the soil into the leaves. Some of the water is used in
the photosynthesis process, and much of it escapes through the stomata. Water that escapes goes back into the
atmosphere.
Environmental factors affect the rate of transpiration. The drier the atmosphere, the greater the driving force for water
movement out of the plant, increasing rates of transpiration.
Pollination is the process by which pollen is transferred from the anther (male part) to the stigma (female part) of
the plant, thereby enabling fertilization and reproduction. This takes place in the angiosperms, the flower bearing plants.
Most plants sprout bisexual flowers (which have both male and female parts), but plants like squash grow separate male
and female flowers — still others have both bisexual and single-sex flowers. And, as evolutionary biologists have recently
discovered, plants with male and bisexual flowers produce more seeds. However not all flowers have both male and
female parts, and some plants have totally separate male and female flowers.
Plants that have either male or female floral parts, but not both are called Dioicous ("two houses").
Plants that have both male and female floral parts are called Monoicous ("one house").
While many angiosperms seem to have both anthers and ovules they may not, whereas pansies and gymnosperms are
very good examples of Diocious flowers.
Common Misconceptions
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Plants take in all substances they need to grow through their roots. In reality, chloroplasts in the plant absorb
the sun’s energy for use in photosynthesis.
Water is absorbed by leaves. It is not, water and minerals are taken in through the roots.
Termly Scientific Skills Development Focus: Evaluation
Questions that should be asked: (For more suggestions see page 16 of the Scheme of Work)
 Are there any results/observations which don’t seem to match others?
 How would you explain any results/observations that you were not expecting?
 How would you use science to explain any results/ observations which don’t seem to match others?
 What could you do to make your method better?
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Opportunities should be given throughout the lesson for children to use and develop their knowledge of planning investigations
and collecting data. They should be encouraged to question the validity of their results.
Cross curricular links
Literacy
 Write a biography for a famous botanist.
 Make a class glossary for Plants and Photosynthesis using new vocabulary
learned. This could be adapted for younger children in school. For example Y6
could make a pictorial one for Y3 children.
 Produce an explanation text on how plants reproduce.
 Research and write a news report on the problem of the decreasing population
of bees.
 Interview a beekeeper and write instructions on keeping bees.
 Bee and Flower poetry – excellent for personification.
 Write the diary of a bee – “A day in the life of…”
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Plants and Photosynthesis– Inside the Leaf, Bees and Pollination
Lessons 5 and 6
Numeracy
Other subjects
 Create some maths problems using plants. Eg if a bee collected 35 grains of
pollen from each of the 8 flowers he visited each day, how many grains of pollen
has he transferred?
 Drawing line graphs to illustrate numerical data.
 Use data to calculate averages.
 Discussion and use of a variety of tables, diagrams.
 More able children may be able to work out surface areas of irregular shapes.
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 Pupils could work on creating a large model of a leaf cross section using
plasticine, modroc or clay.
 Research English vicar called Stephen Hales, who discovered how plants
transport water.
 Make 3D models of flowers, lift the petal to reveal the parts of a flower.
 Either individually or in small groups on a larger scale.
 Painting in the style of Elizabeth Blackadder.
Starter Activity
‘Think-Pair-Share’: What were the five most important facts from last lesson?
‘Snowball’ (Form groups of four from pairs): From your ten most important facts, which are the top five? Feedback to class.
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Activity
Demonstration 1: Examine leaves/celery/flowers from last week.
Children can pass them around, or use a visualiser.
Can children explain what has happened?
In order to replace the lost water, the plant has little tubes inside its stem that transport water up to the leaves from the roots.
When the celery was placed inside of the coloured water, both the water and the food colouring were taken up the tubes and the
colouring was left behind in the leaves when the water evaporated through the stomata!
If you cut the stem open length-wise you should have seen the tubes going all the way up from bottom to top, loaded up with
coloured water.
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Demonstration 2: Bees and Pollination - Flower dissection and Pollen under the microscope + Bees and Honey.
You will need: flowers, tiles, knives, magnifiers
Curiously of all the demonstrations and discussions to be had in science this is perhaps one of the most important! Bees are
incredibly important pollinators and pollination in particular is essential for most life on earth – so it is worth spending some time
on this demonstration and class discussion.
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Watch the clip of pollination: http://www.bbc.co.uk/education/clips/zfx76sg
As a class, work through and play the demo:
http://resources.hwb.wales.gov.uk/VTC/plant_repro/eng/Introduction/default.htm
Using fresh flowers (lilies and tulips are better), carefully dissect a flower and stem. Allow the children to observe this,
and then pass round the parts of the flower.
Children should then be able to identify, label and observe in detail using the microscopes.
Children can then begin to grasp the concept of pollination and the role of bees.
(http://www.bbc.co.uk/guides/zg4dwmn)
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Lessons 5 and 6
Possible Questions/ Suggestions for discussion
 Do you think that any particular food colouring would work better than another? Why don’t you do an experiment and
find out?
 What would happen if you left the flower/celery in the coloured water longer? Explain your reasons for this.
 How much water has been taken up the stem? How could we measure this?
 Would where we placed the pot change our results? What might happen if the pot was left in a warm or a cold place?
Teacher Demonstration
Recap: What have we learnt so far about water in plants?
Demonstration: Measuring rate of water uptake by a plant shoot using a potometer
You will need: bowl of water, stem, photometer, Vaseline/blutac
Explain the potometer to the class: explain how it was set up and that the rate of water uptake by the shoot is measured by
timing how long the air bubble takes to move a set distance, in the capillary tube.
Explain that you cut the shoots under water and assembled the potometer under
water. If air got into the xylem vessels of the plant, it could have formed air locks
that would prevent the plant taking up water.
Explain that the potometer has been left for the leaves to dry or they have been
dried gently with a paper towel. The potometer will not work properly until any
excess water on the leaves has evaporated or been removed.
It is a good idea to assemble the potometer before the lesson, as there is a real
art in setting them up. This will give the leaves time to dry and give you a chance
to check that they are working before you begin to take measurements with the
pupils.
Adding food colouring to the water makes it easier to see the air bubble in the
capillary tube.
See the following links for guidance:
https://www.youtube.com/watch?v=oUr1P9RZnEU
https://www.youtube.com/watch?v=qj7jnqgzHuE
Children’s Investigation
Class Activity:
You will need: microtone, wax, boiling tube, tripour beaker, carrot/celery, scalpel, microscopes for the children
What do stems and leaves look like in cross section? There is a choice of three methods:
1. Use the prepared slides and microscopes to observe the cross sections of a leaf and stem.
2. You can make your own microscope slides using a fresh leaf and a sharp knife. Make sure that the leaf is clean and dry. Lay it
flat on a chopping board, and slice a two centimetre section crosswise from the centre. The cells surrounding the central vein of
the leaf are what you will want to look at so make sure that you cut across the vein. Starting at one of the short end strips (the
edges that you did not cut), tightly roll the leaf section. Carefully make several very thin slices off one end. Make a wet mount on
the slide by adding a few drops of water over the leaf section on the slide and cover with the coverslip. Use the data recording
sheet from www.hometrainingtools.com.
3. Use the microtone to make slides for the children. This MUST be done by an adult.
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Attach the microtone to a table.
Pour some wax crystals into a boiling tube then place both into a beaker of hot water.
Place a chunk of carrot/celery etc into the well of the microtone.
When the wax has melted, pour around the piece of vegetable and leave to set.
Once set, use a scalpel to shave off a thin layer, twist the handle underneath the microtone to move the well upwards
and repeat several times.
 Pass the homemade slides to the children to observe.
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Lessons 5 and 6
Pupils then observe the sections by hand, with a lens and microscope and make accurate neat drawings. Pupils should attempt to
provide precise measurements of what they see in their thin sections.
Children can then use the microscopes to compare slides, draw and label diagrams etc.
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Possible Questions/ Suggestions for discussion
Questions:
What can you see?
Are all stems the same?
Are there any patterns in similar vegetables?
Can you label parts of the leaf?
Identify the guard cells and the stomata to make a detailed drawing.
Plenary: Modelling stem and leaf cross sections.
Show pupils the “stem and leaf structure” PowerPoint to consolidate learning. Print pictures of the cross sections of the stem and
leaf. Then give each group a variety of Plasticine colours and ask them to develop models of the cross sections.
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Learning Outcomes
All children should
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Record measurements in a table and draw a conclusion from them.
Learn about the internal structure of leaves.
Be able to use the microscope.
Learn that stomata are surrounded by two guard cells.
 Recognise that guard cells control the opening/closing of the stomata.
Some children could
A few children could
 Explain their observations using simple arguments.
 Draw a simple line graph.
 Suggest ways in which to improve experimental design.
 Create a fully labelled poster or powerpoint or model of a bee that shows all its
body parts and describes the life and function of a bee. 
 Work together to create models of plant leaves, stomatas, stems, flowers and
bees to form part of a whole class activity, presentation or display for the school.
 Suggest ways to improve the experiment to obtain more meaningful results.
 Suggest how water moves from soil and passes out of leaves, using reasoned
arguments.
 Explain the structure of veins i.e. they have specialised tubes called xylem, (takes
water up), and phloem (takes glucose to where it is needed).
Plenary/Review including Skills Progression focus: Evaluation
Evaluation involves critically considering the reliability of the data and discussing how it can be improved. Pupils explain
whether their evidence is robust enough to support a firm conclusion. They also suggest ideas to enable their investigation to
provide additional relevant evidence.
 Through whole class discussion elicit from the pupils what they observed.
 What do children think they needed to do to ensure that they would get the same results if they or someone else was to
repeat this experiment?
 How could this experiment be improved to make the data more precise, accurate and valid?
 In what ways might this investigation be useful in the real world?
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Lessons 5 and 6
Useful websites
Please see the following www links for lesson support and guidance:
https://www.youtube.com/watch?v=V5yya4elRLw
https://www.youtube.com/watch?v=rmL_XTrPOMw
http://www.bbc.co.uk/bitesize/quiz/q69706711
http://www.bbc.co.uk/bitesize/ks2/science/living_things/plant_life_cycles/read/1/
http://www.bbc.co.uk/programmes/p00nn01z
Great for revision: http://www.saps.org.uk/primary/teaching-resources/239-reproduction-and-life-cycles-part-1parts-of-a-flower
http://www.microscope-microscope.org/activities/school/microtome.htm
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Lessons 5 and 6
NOTES:
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