Biology
Topic 1 Cells and Tissues
Activity: Pollen forensics
Pollen grains are the male reproductive cells (or male gametes) of plants. They are usually
single cells that are protected by a hard outer coat.
Pollen from different types (species) of plant can be different shapes and different sizes.
This allows us to determine the species of plant by looking at the pollen grains under a
microscope.
When honey is made by bees, they collect nectar from flowers and take it back to the hive
where it is stored as honey. In this way, bees also pick up pollen from the male anthers of
the flower and distribute this to any other flowers that they visit on their journey. The result
is that pollen grains get mixed up with the nectar that the bees collect and find their way
into the honey that we extract from the hive.
Consumers have started to ask questions about where their honey comes from, and even
if it is actually real honey at all. We can look at a sample of the honey under a microscope
and observe the pollen grains carefully. This will allow us to identify the type of flowers that
were visited by the bees when collecting the nectar to make the honey.
In this investigation you will be given a sample of pollen taken from honey, together with a
selection of pollen samples from various flowers. You will need to observe and record the
shape and size of the pollen grains, and try to identify which flowers were used by the
bees to make this particular honey.
Method
1
Plug in and set up your microscope, making sure that the objective lens (the one
nearest the stage), is the lowest magnification one (usually 4×).
2
Take a clean dry microscope slide and label it ‘Pollen A’.
3
Take a flower and locate the pollen-producing anthers. This may require careful
dissection of the flower to remove the petals and sepals.
4
Gently tap the pollen from the anthers onto the centre of the labelled slide.
5
Very carefully lower a cover slip over the pollen grains.
6
Place the slide under the microscope and focus onto the pollen grains using the
lowest magnification.
7
Increase the magnification and refocus if necessary.
KS3 Biology Dynamic Learning © Hodder and Stoughton 2013
1
Biology • Topic 1 • Cells and tissues
8
Observe the pollen grains using as high a magnification as possible. Record your
observations by making a drawing on plain paper. Record the pollen size if possible.
9
Repeat the procedure for all flower types that you have been provided with.
10 Compare these with the pollen labelled ‘HONEY SAMPLE’. Attempt to determine
which flowers were used to manufacture the honey.
Questions
1
Which flower was used by the bee to produce the honey? Explain your answer.
2
Can you think of any other explanation for the presence of pollen in the honey
sample?
3
Assuming the pollen grains under the microscope have a diameter of 0.1 mm,
calculate the magnification of one of your drawings.
KS3 Biology Dynamic Learning © Hodder and Stoughton 2013
2