Summative Practice Chapter 8 – Question 1 – 5 (Form 4 Biology Textbook Exercise and Answer)

Question 1:
Explain why a transportation system is not required to transport respiratory gases in insects.

Each cell in an insect’s body is supplied with a tracheole that directly enters the cell to enable gaseous exchange.

Question 2:
Why are the lungs of amphibians not as efficient as human lungs?

Amphibians do not have rib cage and diaphragm to help in the expansion and compression of the lungs.

Question 3:
The diaphragm of an individual no longer functions normally due to an accident. Explain how this condition affects the breathing mechanism of the individual.

Breathing becomes difficult because the volume and air pressure of the thoracic cavity cannot be increased nor decreased.

Question 4:
How does an increase in heartbeat rate during an emergency, help a person to face the emergency?

The increase in the rate of heartbeat causes oxygenated blood to flow to cells at a faster rate. This enables cellular respiration to occur at a faster rate to supply extra energy required during the state of panic. At the same time, carbon dioxide can be expelled at a faster rate.

Question 5:
(a) A hardcore smoker can easily suffer from a prolonged cough. Explain how this condition affects the function of the respiratory system.

(b) Describe another illness that may be easily contracted by a hardcore smoker.

(c) Explain the effects of tar that is present in cigarette smoke on the smoker.

• The heat generated from cigarettes dries up the tracheal wall and damages cilia. The cilia produce more mucus.

• Coughing is a reflex action to expel mucus. Cigarette smoke damages the alveoli, reducing the total surface area for gaseous exchange. This causes emphysema.

Lung cancer is caused by carcinogens that induce the growth of cancer cells.

Tar that is deposited on the surface of alveoli, blackens them, reduces the efficiency of gaseous exchange and may cause cancer.

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