Page 142 - Biology Form Two

Biology for Secondary Schools

Health status to adults. This condition increases the
Generally, the rate of gas exchange demand for oxygen so as the rate of gas
increases when a person is sick. This exchange.
is due to increased metabolism by the
liver during the removal of the toxins Exercise 6.1
FOR ONLINE READING ONLY
released by disease-causing micro-
organisms or break down of the drugs 1. Describe the functions of each
taken. Certain diseases such as asthma of the labeled parts in relation to
make the body weak and slow down gas exchange in mammals.
the breathing process. Asthma is an
inflammation in the respiratory airways
which affects gas exchange. The (b)
inflammation happens due to allergic
reactions caused by allergens such as (a) (c)
pollen, smoke, and strong smell in the
air. Asthma makes breathing difficult
because the respiratory airways (e)
become very narrow when they are (d)
inflamed. This reduces the rate of gas
exchange. 2. Explain why

Altitude (a) the rate of breathing
Altitude is the height above sea level. The increases during physical
concentration of oxygen is lower at high exercise; and
altitudes, than at low altitudes. This is (b) your breathing rate does not
due to reduced pressure at high altitudes go back to normal as soon
compared to low altitudes. Breathing as you stop exercising.
rate is also higher at high altitudes than
at low altitudes due to the decreased 3. Answer the following questions
atmospheric pressure, resulting in briefly.
breathing difficulty. Therefore, the rate (a) Why is it better to breathe
of gas exchange has to increase in order through the nose than
to obtain enough oxygen. through the mouth?

(b) What would happen if the
Age
Young people are generally more epiglottis was removed from
the human body?
active than old people. In addition,
many growth processes take place in (c) Explain how breathing takes
the bodies of young people compared place in human beings.

136 Student’s Book - Form Two

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BIOLOGY FORM 2 NEW.indd 136
BIOLOGY FORM 2 NEW.indd 136 05/10/2024 15:36:44