Page 29 - Science Coursebook

2.3 Ecology

Questions

SE 6 Suggest how the students in the photographs could
use the net to sample the invertebrates in the river.

SE 7 Suggest how the students could find out if there is
a correlation between the number of invertebrates
and the concentration of dissolved oxygen.

The students use an oxygen meter
to measure the concentration of
dissolved oxygen in the water.

Activity 2.3

An ecology investigation

SE You are going to plan an experiment to find out the answer
to a question about ecology. You could do your experiment
in the school grounds.

Go for a walk around the school grounds, looking closely
at the organisms that you find. Think about a question that

you could investigate. Questions about plants are usually
easier to try to answer than questions about animals.
For example:

• Are there more daisy plants in sunny places than in
shady places?
• Does grass grow faster where people don’t walk on it?
Now plan your investigation. You will probably want to
use a sampling technique. Ecologists often mark out little
square plots with sides 0.5 m long. A quick way of doing
this is to make a frame exactly that shape and size, which
you can put down onto the ground. This frame is called
a quadrat.
Once you have chosen the two areas you are going to
sample, you need to try to place your quadrats randomly
inside them. One way of doing this is to stand with your This ecologist is using a quadrat
back to the area and throw your quadrat behind you marked out in smaller squares, to
– but do make sure there is no-one standing nearby! Your make it easier for her to count the
teacher may be able to suggest other ways of doing this. plants inside it.

Summary
• Ecologists study organisms in their environment.

• Ecologists often use sampling techniques. Sampling involves finding

results for a small, representative part of the area you are studying.

2 Living things in their environment 27