Biology

Respiration and Gas Exchange

958 Questions

Access a targeted set of questions on respiration and gas exchange for competitive exams. Topics include lung volumes, the mechanism of breathing, and respiratory anatomy. Understanding these physiological processes is essential for scoring well.

Lung volumes and capacitiesBreathing mechanismsRespiratory anatomyGas exchange processes

Respiration and Gas Exchange Questions

Multiple choice

Where does the exchange of gases take place during breathing?

  1. Nostrils

  2. Trachea

  3. Alveoli

  4. Bronchioles
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The exchange of gases takes place in the alveoli. The walls of the alveoli are surrounded by a network of blood capillaries. Thin walls of alveoli and capillaries allow for O2 to enter the capillaries and CO2 to enter the alveoli for exhalation.

Multiple choice

Which of the following regulate(s) the mechanism of breathing through deepening the inhale?

  1. Peripheral chemoreceptors

  2. Central chemoreceptors

  3. Nasopulmonary and nasothoracic reflexes

  4. Spinal cord reflex

  5. Hering-Breuer reflex
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The nasopulmonary and nasothoracic reflexes govern the mechanism of breathing through deepening the inhale. Triggered by the flow of air, the pressure of the air in the nose, and the quality of the air, impulses from the nasal mucosa are transmitted by the trigeminal nerve to the breathing centres in the brainstem and the generated response is transmitted to the bronchi, the intercostal muscles and the diaphragm.

Multiple choice

Fibrosing alveolitis is characterised by inflammation, damage and progressive fibrosis of the lungs. Which of the following statements about idiopathic fibrosing alveolitis is correct?

  1. Patients are usually young.

  2. Antineutrophil cytoplasmic antibodies are positive in 90% of patients at presentation.

  3. 50% of patients die within 6 months of diagnosis.

  4. A chest X-ray can show a 'ground-glass' appearance.

  5. Lung transplantation is never effective in such patients.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This is a typical feature of idiopathic fibrosing alveolitis.

Multiple choice

In mammals, which of the following is regarded as the balance point between the inward elastic recoil of the lungs and the outward elastic recoil of the chest wall?

  1. Expiratory reserve volume

  2. Inspiratory capacity

  3. Vital capacity

  4. Total lung capacity

  5. Functional residual capacity
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

It is the volume of gas remaining in the lungs at the end of a normal tidal expiration. It is the balance point between the inward elastic recoil of the lungs and the outward elastic recoil of the chest wall.

Multiple choice

Select the correct statement regarding airways and lung alveoli.

  1. The mucus lining the upper airways is mainly produced by mucosal glands.

  2. The cartilage in the walls of trachea, bronchi and bronchioles prevents them from disrupting.

  3. The small diameter airways are the main sites of airways resistance.

  4. The upper airways play a crucial role in protecting the lungs from airborne particles.

  5. The alveoli are the only sites of gas exchange.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The airways epithelium play a crucial role in protecting pulmonary tissue from foreign substances by synthesising, mechanical, innate and acquired host defense systems. Airborne particles including pathogens, are absorbed by the layer of mucus lining the airways, where they are destroyed and removed through mucociliary and cough clearance.

Multiple choice

Lung capacity is defined as the maximum air which can be held in the lungs at any given time. Which among the following has the minimum value?

  1. Alveolar air

  2. Residual air

  3. Inspiratory reserve volume

  4. Expiratory reserve volume

  5. Vital capacity
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Alveolar air is the gas in the pulmonary alveoli, where O2-CO2 exchange with pulmonary capillary blood occurs. Some amount of air remains in the various parts of the respiratory tract. The air in the trachea and bronchi (where no diffusion occurs) is called dead space air (350 ml). The air remaining in the alveoli or air sacs is alveolar air (150 ml).

Multiple choice

Which of the following statements is correct about ventilation and gaseous exchange of mammals?

  1. Inspired air is dried in the nasal cavity.

  2. The anatomical dead space is independent of the tidal volume.

  3. In an upright lung, the alveolar ventilation is maximum at the base.

  4. The ventilation ratio for an organism in a sitting position decreases with distance above the base of the lung.

  5. The anatomical dead space is the volume of air taken in during a breath that does not enter the alveoli.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

It is the correct statement as the dead space is the volume of air which is inhaled but does not take part in the gas exchange. It either remains in the conducting airways or reaches alveoli that are not perfused or poorly perfused.

Multiple choice

Which of the following structures is responsible for warming and moistening the inhaled air in human beings?

  1. The laryngopharynx

  2. The oropharynx

  3. The larynx

  4. The nasopharynx

  5. The nasal cavity
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The nasal cavity is a hollow space within the nose and skull that is lined with hairs and mucus membrane. It provides enough surface area for the inhaled air to be warmed and moistened, within fractions of a second, before reaching the lungs.

Multiple choice

Sea animals like dolphins and whales breathe in air through

  1. nostrils

  2. lungs

  3. skin

  4. gills
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Dolphins and whales neither have gills nor lungs to take in air and to breathe, these animals come at the surface of water, absorb the oxygen from air through their nostrils and remain in water for long periods by utilising this oxygen gradually.