Breathing and Exchange of Gases
Test 1

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following statements about oxygen transport is correct?

Oxygen is primarily transported as bicarbonate ions
Most oxygen binds reversibly with hemoglobin
Oxygen is more soluble in plasma than CO₂
Oxygen transport is independent of partial pressure
2

Most oxygen in the blood binds reversibly with hemoglobin, forming oxyhemoglobin.

Which of the following is true about carbon dioxide transport?

CO₂ is mostly carried by hemoglobin
CO₂ is transported mainly as bicarbonate ions
CO₂ transport is independent of partial pressure
CO₂ is actively transported into alveoli
2

About 70% of carbon dioxide is transported in the blood as bicarbonate ions (HCO₃⁻).

Which lung capacity represents the total amount of air that can be expired after a normal inspiration?

Tidal Volume
Expiratory Capacity
Vital Capacity
Total Lung Capacity
2

Expiratory Capacity (EC) is the total amount of air a person can expire after a normal inspiration (TV + ERV).

Which of the following statements about human respiration is correct?

The trachea divides into two primary bronchi at the 5th thoracic vertebra.
The alveoli are lined with a thick muscular layer to prevent collapse.
Lungs are covered by a single pleural membrane.
The diaphragm remains fixed during breathing movements.
1

The trachea divides into right and left primary bronchi at the level of the 5th thoracic vertebra, making this statement correct.

Which of the following statements about gas exchange is incorrect?

Gas exchange occurs by simple diffusion.
Alveoli provide a large surface area for diffusion.
The partial pressure of CO₂ is higher in alveolar air than in venous blood.
O₂ diffuses from alveoli to blood due to a concentration gradient.
3

The partial pressure of CO₂ is higher in venous blood than in alveolar air, allowing diffusion from blood to alveoli. Therefore, statement 3 is incorrect.

Which of the following statements regarding lung capacities is correct?

Vital capacity is the total volume of air the lungs can hold.
Residual volume prevents lung collapse after forced expiration.
Tidal volume includes inspiratory reserve volume.
Total lung capacity excludes residual volume.
2

Residual volume prevents lung collapse after forced expiration, making statement 2 correct.

Which of the following statements about the respiratory system is incorrect?

The pleural fluid reduces friction between the lung surface and thoracic cavity.
The right lung has three lobes, while the left lung has two lobes.
Inspiration occurs when intrapulmonary pressure is greater than atmospheric pressure.
Oxygen diffuses from alveoli to blood, while carbon dioxide diffuses in the opposite direction.
3

Inspiration occurs when intrapulmonary pressure is **less** than atmospheric pressure, allowing air to flow into the lungs. Therefore, statement 3 is incorrect.

What is the function of the alveolar membrane in gas exchange?

It actively transports gases
It increases diffusion distance
It facilitates diffusion of oxygen and carbon dioxide
It produces surfactant
3

The alveolar membrane allows efficient diffusion of oxygen into blood and carbon dioxide into the alveoli.

Which of the following is an occupational lung disease caused by prolonged exposure to dust?

Asthma
Emphysema
Silicosis
Pneumonia
3

Silicosis is caused by prolonged exposure to silica dust, leading to fibrosis and lung damage.

What is the primary function of residual volume in the lungs?

Enhances oxygen diffusion
Prevents lung collapse
Reduces alveolar pressure
Increases tidal volume
2

Residual Volume (RV) is the air that remains in the lungs after forced expiration, preventing lung collapse.

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