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Quiz Chapter 2: Respiration

10 questions ยท Form 3 Science Bab 2: Respiration

Question 1 of 10Score: 0

When oxygen enters the bloodstream at the alveoli, it combines with hemoglobin in red blood cells to form:

Full Question List & Answer Key

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

1. When oxygen enters the bloodstream at the alveoli, it combines with hemoglobin in red blood cells to form:

  1. Carboxyhemoglobin
  2. Oxyhemoglobin
  3. Carbaminohemoglobin
  4. Hydroxyehemoglobin
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Answer: B

Oxygen binds reversibly with hemoglobin in red blood cells to form oxyhemoglobin for transport to body tissues.

2. By which process does gas exchange occur across the walls of alveoli and blood capillaries?

  1. Active transport
  2. Osmosis
  3. Diffusion
  4. Transpiration
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Answer: C

Gaseous exchange takes place passively by diffusion down a partial pressure gradient.

3. What is the correct pathway taken by air through the human respiratory tract during inhalation?

  1. Nasal cavity -> Pharynx -> Larynx -> Trachea -> Bronchus -> Bronchiole -> Alveolus
  2. Nasal cavity -> Larynx -> Pharynx -> Bronchus -> Trachea -> Bronchiole -> Alveolus
  3. Pharynx -> Nasal cavity -> Trachea -> Larynx -> Bronchiole -> Bronchus -> Alveolus
  4. Nasal cavity -> Trachea -> Pharynx -> Larynx -> Bronchiole -> Bronchus -> Alveolus
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Answer: A

Air travels in order through the nasal cavity, pharynx, larynx, trachea, primary bronchi, bronchioles, and finally reaches the alveoli.

4. In the human respiratory system, what is the main function of cilia and mucus in the nasal cavity and trachea?

  1. To absorb oxygen directly into blood vessels
  2. To trap dust particles and micro-organisms and sweep them away from lungs
  3. To cool down incoming atmospheric air
  4. To produce carbon dioxide for exhalation
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Answer: B

Mucus traps foreign dirt and pathogens, while microscopic hair-like cilia sweep the trapped debris up toward the pharynx.

5. Which respiratory muscle relaxes and forms a dome shape during human exhalation?

  1. External intercostal muscle
  2. Diaphragm muscle
  3. Abdominal muscle
  4. Pectoral muscle
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Answer: B

During exhalation, the diaphragm relaxes and curves upward into its natural dome shape.

6. How does heavy atmospheric haze affect plant growth?

  1. It speeds up stomatal opening during the night
  2. Dust particles block stomatal pores, decreasing photosynthesis and transpiration rates
  3. It increases the concentration of oxygen around leaf guard cells
  4. It forces guard cells to stay permanently turgid
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Answer: B

Haze and particulate dust coat leaf surfaces and clog stomata, impeding gas exchange ($CO_2$ absorption) needed for photosynthesis.

7. An adult frog can perform gas exchange through its skin when submerged in moist soil. What feature allows its skin to be effective for gas exchange?

  1. Presence of thick chitinous scales
  2. Thin, moist skin richly supplied with blood capillaries underneath
  3. Specialized spiracles embedded along the outer dermis
  4. Large surface area covered by gill filaments
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Answer: B

A frog's skin is thin, kept constantly moist by mucus secretions, and well-supplied with blood capillaries for rapid diffusion.

8. Why do fish die when kept out of water for an extended period, even though air has a higher percentage of oxygen than water?

  1. Air lacks nitrogen required for fish respiration
  2. Gill filaments stick together and dry out in air, drastically reducing surface area for diffusion
  3. Fish spiracles automatically close when exposed to atmospheric air
  4. Carbon dioxide cannot diffuse into open air from lamellae
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Answer: B

Without water to support them, delicate gill filaments collapse, stick together, and dry up, reducing surface area and causing suffocation.

9. How does oxygen reach individual body tissue cells in an insect like a grasshopper?

  1. Hemoglobin in blood cells carries oxygen from spiracles to muscles
  2. Air diffuses directly through tracheoles into body tissue cells
  3. Oxygen diffuses into the moist outer cuticle and enters systemic circulation
  4. Gills collect dissolved oxygen from body fluid
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Answer: B

Insects use a tracheal system where air enters spiracles and travels through tracheae and tracheoles, diffusing directly into tissue cells.

10. Which change occurs during human inhalation?

  1. The intercostal muscles relax and the ribcage moves downwards
  2. The diaphragm muscle contracts and flattens
  3. The volume of the thoracic cavity decreases
  4. The air pressure in the thoracic cavity increases above atmospheric pressure
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Answer: B

During inhalation, the diaphragm contracts and flattens, while intercostal muscles contract to lift the ribcage, expanding cavity volume.

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