Respiratory System – NDA Biology PYQs

NDA 2026-I

Q. 1. Which of the following properties of alveoli is/are helpful in gaseous exchange during respiration in human beings?

I. The epithelial lining of alveoli is very thin.

II. Elastic fibres are present in alveolar wall.

III. Wall of alveoli is surrounded by many blood capillaries.

Select the correct answer using the code given below.

(a) I and II only

(b) I and III only

(c) III only

(d) I, II and III

Answer: (d) I, II and III

Explanation: All three properties contribute to efficient gaseous exchange in alveoli. Statement I: the extremely thin epithelial lining (one cell thick) allows rapid diffusion of gases. Statement II: elastic fibres allow alveoli to expand during inhalation and recoil during exhalation, maintaining airflow. Statement III: the dense network of blood capillaries around alveoli ensures a steep concentration gradient for O₂ and CO₂, maximising the rate of diffusion. Concept Tested: Structural adaptations of alveoli for efficient gaseous exchange: thin lining, elastic fibres, dense capillary network

★ JOVIK Exam Insight When NDA asks about alveolar adaptations, all three: thin epithelium, elastic fibres, and rich capillary supply: are correct. Do not exclude elastic fibres from the answer.

Q. 2. In which of the following parts of organisms, the process of gaseous exchange during respiration does not take place?

(a) Skin of earthworms

(b) Bronchi of humans

(c) Gills of Pila

(d) Alveoli of humans

Answer: (b) Bronchi of humans

Explanation: Gaseous exchange is the diffusion of O₂ into the blood and CO₂ out of it. In earthworms, exchange occurs through the moist skin. In Pila (apple snail), gills perform gaseous exchange. In humans, alveoli are the site of gaseous exchange. Bronchi are conducting airways: they carry air to and from the alveoli. No gaseous exchange occurs in the bronchi; they are part of the dead space. Concept Tested: Bronchi are conducting airways, not gas-exchange surfaces; gaseous exchange occurs only at alveoli

Q. 3. Which one of the following respiratory volumes of human lung is the lowest?

(a) Residual volume

(b) Tidal volume

(c) Inspiratory reserve volume

(d) Expiratory reserve volume

Answer: (b) Tidal volume

Explanation: Tidal volume is the amount of air inhaled or exhaled during normal quiet breathing: approximately 500 mL. Inspiratory reserve volume (~2500–3000 mL) is the extra air that can be forcefully inhaled. Expiratory reserve volume (~1000–1200 mL) is the extra air forcefully exhaled. Residual volume (~1100–1200 mL) is the air remaining after maximum exhalation. Tidal volume is the lowest among these four. Concept Tested: Tidal volume (~500 mL) is the lowest respiratory volume; IRV is the highest

★ JOVIK Exam Insight Typical lung volume values for NDA: Tidal Volume ~500 mL (lowest), Expiratory Reserve Volume ~1000–1200 mL, Residual Volume ~1100–1200 mL, Inspiratory Reserve Volume ~2500–3000 mL (highest). Vital Capacity = TV + IRV + ERV.

 NDA 2025-II

Q. 4. The amount of air breathed in and out during a normal respiration by human lungs is referred to as

(a) Vital capacity

(b) Tidal volume

(c) Inspiratory volume

(d) Total lung capacity

Answer: (b) Tidal volume

Explanation: Tidal volume is the volume of air inhaled or exhaled during a single normal breathing cycle at rest. Its typical value is approximately 500 mL (0.5 L). Vital capacity is the maximum air that can be exhaled after maximum inhalation. Total lung capacity is the total air the lungs can hold. Inspiratory volume refers to the air drawn in during inhalation and is not the standard term for normal breathing volume. Concept Tested: Tidal volume: volume of air breathed in and out during normal quiet respiration (~500 mL)

 NDA 2018-I

Q. 5. Which one of the following parts of body does NOT take part in the process of breathing?

(a) Bronchi

(b) Bowman’s capsule

(c) Diaphragm

(d) Trachea

Answer: (b) Bowman’s capsule

Explanation: Bowman’s capsule is part of the nephron in the kidney. It is involved in filtration during urine formation, not in breathing. Bronchi are conducting airways that carry air into and out of the lungs. The diaphragm is the primary muscle of breathing: it contracts to increase thoracic volume during inhalation. The trachea is the windpipe that connects the larynx to the bronchi. Concept Tested: Bowman’s capsule is a renal (kidney) structure, not involved in breathing

 NDA 2011-II

Q. 6. A man was trapped in a room of a building which was up in flames. Fire-fighters had to break window panes which were filled in smoke to take him out. Once the injured person is out, he should be observed/treated for

(a) Superficial burn wound

(b) Electric burn wound

(c) Respiratory burn

(d) Internal organ injury

Answer: (c) Respiratory burn

Explanation: The person was exposed to a smoke-filled room for an extended period. Smoke contains hot gases, carbon monoxide, and toxic particles. Inhalation of smoke damages the airways, trachea, and lung tissue: a condition called respiratory burn or inhalation injury. This is the primary risk in such situations. Superficial or electric burns require direct flame or electrical contact, which is not described here. Concept Tested: Smoke inhalation causes respiratory burn (inhalation injury) to the airways and lungs

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