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Quiz Chapter 8: Respiratory Systems in Humans and Animals

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

Question 1 of 10Score: 0

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

Full Question List & Answer Key

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

1. 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.

2. 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.

3. 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.

4. What happens to thoracic cavity pressure during human EXHALATION?

  1. A. Pressure drops below atmospheric pressure.
  2. B. Pressure increases above atmospheric pressure.
  3. C. Pressure remains equal to atmospheric pressure.
  4. D. Pressure reaches zero.
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Answer: B

Decreasing thoracic volume during exhalation increases internal pulmonary pressure above atmospheric pressure, pushing air out of the lungs.

5. 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.

6. Which respiratory disorder involves chronic allergic inflammation, smooth muscle contraction, and narrowing of bronchioles?

  1. A. Emphysema
  2. B. Asthma
  3. C. Lung cancer
  4. D. Tuberculosis
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Answer: B

Asthma is characterized by hypersensitive, inflamed bronchioles that constrict during attacks.

7. 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.

8. 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.

9. Why are human capillaries and alveoli wall membranes only one cell thick?

  1. A. To withstand high mechanical pressure
  2. B. To shorten the diffusion distance for gas exchange
  3. C. To prevent water evaporation
  4. D. To store excess oxyhemoglobin
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Answer: B

Thin walls shorten diffusion pathways, allowing rapid transport of oxygen and carbon dioxide.

10. Which change occurs to blood pH when carbon dioxide concentration increases rapidly during heavy exercise?

  1. A. Blood pH increases (becomes alkaline).
  2. B. Blood pH decreases (becomes acidic).
  3. C. Blood pH remains unchanged.
  4. D. Blood pH fluctuates to zero.
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Answer: B

Increased CO2 reacts with water to form carbonic acid and H+ ions, lowering blood pH (acidic shift).

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