1. LO: Learn how to interpret population curves.
Keywords:
Predator
Prey
Cycle
Population Curves
Lifelines:
WRITING: W2, W4
TALKING: T2, T5
LO: Learn how to interpret population curves.
Learning challenges:
Use data to describe the relationship between predator and prey.
Explain why predator and prey numbers rise and fall in cycles.
Suggest why there is a time delay before the numbers of predator increase.

2. Predator-prey populations
How does the lynx population depend on the number of snowshoe hares? 50
estimated population size (thousands)
1800
1820
1840
1860
1880
1900
100
150
year
lynx
snowshoe
hare
Take a closer
look at this part
of the graph.

3. Predator-prey populations
Why does the peak for the lynx population always come after the peak for the number of snowshoe hares?
snowshoe
hare
150
lynx
For the populations
to survive, there must always be more hares than lynxes
100
estimated population size (thousands) 50
1845
1850
1855
1860
1865
year

4. Population Curves Rabbit Fox Population of animal Time / months C A B
Match the statements to parts A B or C on the graph.
As the population of predators decreases the population of rabbits increases, as less rabbits are being eaten.
The population of predators increases at a slower rate because they rely on the prey for energy.
When the population of foxes peaks, there isn’t enough prey to sustain the population. This causes the number of rabbits to sharply decrease.

5. Population Curves
Look at the graph carefully and answer the following questions:
Name the prey and predator shown by this graph (1 mark)
Prey:……………..
Predator:……………..
Use the graph to explain the predator-prey relationship shown. (3 marks)
1 mark – the population of plant plankton increases/more of them
1 mark - the number of animal plankton rises because there is more food available to them
1 – mark – the animal plankton population falls as they compete for the limited amount of plant plankton

6. Independent Task Peer assessment task: Purple Pen Reflection:
Complete the worksheet on slugs and toads.
Peer assessment task:
Comment on the use of keywords (W2)
Has the work been explained in detail (T5) – highlight an example of this
Comment on the spelling of key words (W4)
Purple Pen Reflection:
Why do the numbers of predators and prey rise and fall in cycles?