Page 45 - ScienceStd4

by allergies caused by environmental factors such as smoke,
dust, perfume, soap and pollen. The allergy causes the airways
to swell and produce thick mucus. This swelling makes it hard
to breathe and a person gets an asthma attack.
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Symptoms of asthma

Symptoms of asthma include:

(a) Coughing, sneezing and a runny nose;

(b) Tightness and pain in the chest and ribs; and

(c) Shortness of breath with a wheezing or whistling sound.

Prevention of asthma

Asthma is a chronic condition with no cure. Asthma attacks can
be prevented by:

(a) Avoiding asthma triggers like pollen and perfumes; and

(b) Getting treatment immediately after getting asthma
symptoms.

Exercise 8

1. How can different lifestyles cause diabetes?

2. List three things that can trigger asthma.

3. How can cancer be prevented?

Life cycle of insects which spread diseases

Insects like houseflies, mosquitoes and cockroaches spread

diseases. These insects have different growth stages through
which they change their shape and behaviour. These changes are
called metamorphosis. There are two types of metamorphosis
namely: complete and incomplete metamorphosis. Complete

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