Page 140 - Biology Form Two

Biology for Secondary Schools

3. Pull the rubber sheet downward the mammalian respiratory system
gently as shown in Figure 6.6. in Figure 6.1. Summarise your
What happens? results in a tabular form.
Gas exchange across the alveolus
FOR ONLINE READING ONLY
Task 6.4
Search the library and internet sources
for animations or simulations on the
mechanism of gas exchange across the

alveolus. Make observation and write
brief notes.

The actual exchange of oxygen and
carbon dioxide takes place in the
Figure 6.6: Pulling the rubber sheet alveoli found in the lungs. Alveoli are
downward tiny balloon-like air sacs located at
the end of each bronchiole, where the
4. Note down the results for each exchange of oxygen from the lungs and
action you have performed. carbon dioxide from the blood occurs.
5. Explain clearly the reason for each One mammalian lung has millions of
of the observations. alveoli. The number of alveoli in the

6. Compare parts of the respiratory lungs can differ from one person to
system represented by each item another. The alveoli are surrounded by
in this experimental set-up with a network of capillaries, as shown in
Figure 6.7.

Deoxygenated
blood enters Oxygen gas
entering the blood
Oxygenated
blood leaves
Capillary

Carbon dioxide gas
leaving the blood

Oxygen rich air
Carbon dioxide rich air
Figure 6.7: Gas exchange across the alveolus

134 Student’s Book - Form Two

05/10/2024 15:36:44
BIOLOGY FORM 2 NEW.indd 134 05/10/2024 15:36:44
BIOLOGY FORM 2 NEW.indd 134