Page 21 - 新思维科学活动用书8 样章

1 Respiration

Exercise 1.5C Rats at altitude

Challenge

In this challenging task, you will use information to make a prediction. You will draw a graph to
display a set of results, and think about the design of an experiment.

Red blood cells carry oxygen around the body. At high altitudes, there is less oxygen in the air.
A team of scientists did an experiment to find out how the number of red blood cells in rats changed
when the rats were taken to high altitude.

1 Make a prediction about what might happen to the number of red blood cells when the rats
were taken to high altitude.
Explain your prediction.

This is what the scientists did.

• They kept one group of rats at sea level, and took another group to high altitude.
• They took blood samples from each rat on days 1, 3, 7, 15 and 20.
• They measured the number of red blood cells in a certain volume of blood from each rat.
This is called the red blood cell count.
• They calculated the mean red blood cell count for

each group of rats.

20