CHAPTER 7 GASEOUS EXCHANGE (Week 11)

1. Most of the carbon dioxide produced by the body tissues is transported to the lungs in the form of

• A. Carbonic acid
• B. Carbaminohaemoglobin
• C. Blood plasma
• D. Bicarbonate ions

2. The following reaction shows the affinity of haemoglobin towards oxygen in animal tissues under condition X and Y.

• A. X = High partial pressure of O2 Y = Low partial pressure of CO2

• B. X = High partial pressure of O2 Y = High partial pressure of CO2

• C. X = Low partial pressure of O2 Y = High partial pressure of CO2

• D. X = High temperature Y = Low hydrogen ion concentration

3. One molecule of haemoglobin consists of

• A. One polypeptide subunit, one haem group, one Fe²⁺ ion

• B. One polypeptide subunit, one haem group, four Fe²⁺ ion

• C. Four polypeptide subunits, four haem group, four Fe²⁺ ion

• D. Four polypeptide subunits, four haem groups, one Fe²⁺ ion

4. Where does gas exchange take place in the lungs?

• A. Alveolus

• B. Bronchus

• C. Bronchiole

• D. Trachea

5. What is the most important chemical stimulus in regulating the rate of respiration?

• A. O₂ concentration

• B. CO concentration

• C. CO₂ concentration

• D. N_² concentration

6. What is a chemoreceptor?

• A. A sensory receptor that responds to a chemical stimulus.

• B. A sensory receptor that control the respiration in human.

• C. A sensory receptor that responds to the pressure of CO_² in human blood.

• D. A sensory receptor that connect to breathing control centre.

7. The two types of chemoreceptors are

• A. Phrenic nerve and thoracic nerve.

• B. Intercostal muscle and diaphragm.

• C. Aortic bodies and carotid bodies.

• D. Central chemoreceptor and peripheral chemoreceptor.

8. Breathing centre communicate with the following effectors via which nerves?

• A. Diaphragm : phrenic nerve

  External intercostal muscle : vagus nerve

• B. Diaphragm : vagus nerve

  External intercostal muscle : intercostal nerve

• C. Diaphragm : phrenic nerve

  External intercostal muscle : thoracic nerve

• B. Diaphragm : intercostal nerve

  External intercostal muscle : Phrenic nerve

9. All the following statements are the function of central chemoreceptor EXCEPT

• A. To ensure O_² delivery to nervous system

• B. Responds to changes in CO₂ concentration in cerebrospinal fluid.

• C. Monitors pH in cerebrospinal fluid.

• D. Controls the concentration of CO₂ in cerebrospinal fluid.

10. The opening of stomata is regulated by ....

• A. the accumulation of K⁺ ions in guard cell.

• B. the accumulation of K⁺ ions in epidermis cell.

• C. the absence of light

• D. the uneven thickness of guard cell's walls.