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Quiz Chapter 8: Respiratory Systems in Humans and Animals

10 questions · Form 4 Biology Bab 8: Respiratory Systems in Humans and Animals

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Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. In what form is the majority (approximately 70%) of carbon dioxide transported in human blood plasma?

  1. A. Dissolved carbon dioxide gas
  2. B. Carbaminohemoglobin
  3. C. Bicarbonate ions (HCO3-)
  4. D. Carbonic acid (H2CO3)
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Answer: C

About 70% of CO2 is converted inside red blood cells into bicarbonate ions (HCO3-), which diffuse into blood plasma for transport.

2. Why does oxygen move from alveolar air into blood capillaries during internal gas exchange?

  1. A. Active transport pumps oxygen across the membrane.
  2. B. Partial pressure of oxygen in alveolar air is higher than in capillary blood.
  3. C. Hemoglobin repels carbon dioxide into alveoli.
  4. D. Atmospheric pressure forces red blood cells into alveoli.
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Answer: B

Gases diffuse down partial pressure gradients; oxygen moves from high partial pressure in alveoli to lower partial pressure in blood.

3. Valved external openings along the sides of an insect's thorax and abdomen that control air entry into tracheae are called:

  1. A. Bronchioles
  2. B. Spiracles
  3. C. Opercula
  4. D. Lamellae
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Answer: B

Spiracles are lateral pores on an insect's body through which air enters the tracheal network.

4. What is the primary advantage of the countercurrent exchange system in fish gills?

  1. A. It reduces water loss during swimming.
  2. B. It maintains a continuous concentration gradient for maximum oxygen absorption along the entire lamella.
  3. C. It allows fish to store carbon dioxide in the operculum.
  4. D. It pumps air directly into the swim bladder.
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Answer: B

In countercurrent flow, blood moves opposite to water flow, ensuring oxygen concentration in water is always higher than in blood across the lamella.

5. How does a frog draw air into its mouth cavity during the first stage of ventilation?

  1. A. By contracting its diaphragm
  2. B. By lowering the floor of its buccal cavity while nostrils are open
  3. C. By opening its operculum flap
  4. D. By contracting its abdominal spiracles
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Answer: B

Frogs use positive pressure breathing; lowering the buccal cavity floor increases volume and draws air in through open nostrils.

6. Which respiratory condition is characterized by the breakdown and loss of elasticity of alveolar walls, reducing surface area for gas exchange?

  1. A. Asthma
  2. B. Emphysema
  3. C. Chronic bronchitis
  4. D. Pneumonia
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Answer: B

Emphysema damages alveolar walls, drastically reducing effective surface area and causing severe breathlessness.

7. Which microscopic functional unit in human lungs provides the primary surface for gas exchange?

  1. A. Bronchus
  2. B. Alveolus
  3. C. Trachea
  4. D. Epiglottis
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Answer: B

Alveoli are tiny, highly vascularized air sacs where gas exchange occurs in human lungs.

8. What is carbaminohemoglobin?

  1. A. Hemoglobin bound to oxygen
  2. B. Hemoglobin bound to carbon dioxide
  3. C. Hemoglobin bound to carbon monoxide
  4. D. Hemoglobin bound to bicarbonate ions
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Answer: B

Approximately 23% of carbon dioxide binds directly to amino groups of hemoglobin to form carbaminohemoglobin.

9. Which enzyme inside human red blood cells catalyzes the reversible reaction between carbon dioxide and water to form carbonic acid?

  1. A. Amylase
  2. B. Carbonic anhydrase
  3. C. Alcohol dehydrogenase
  4. D. Pepsin
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Answer: B

Carbonic anhydrase speeds up the reaction between CO2 and H2O to form carbonic acid (H2CO3) in erythrocytes.

10. The respiratory organ flap in bony fish that protects gills and helps regulate water flow pressure is the:

  1. A. Spiracle
  2. B. Operculum
  3. C. Tracheole
  4. D. Alveolus
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Answer: B

The operculum is the protective bony flap covering fish gills that aids in pumping water across lamellae.

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