Please refer to Breathing and Exchange of Gases Class 11 Biology Important Questions with answers below. These solved questions for Chapter 17 Breathing and Exchange of Gases in NCERT Book for Class 11 Biology have been prepared based on the latest syllabus and examination guidelines issued by CBSE, NCERT, and KVS. Students should learn these solved problems properly as these will help them to get better marks in your class tests and examinations. You will also be able to understand how to write answers properly. Revise these questions and answers regularly. We have provided Notes for Class 11 Biology for all chapters in your textbooks.

Important Questions Class 11 Biology Chapter 17 Breathing and Exchange of Gases

Objective Questions

Question. The structure which prevents the entry of food into the windpipe is
(a) gullet
(b) glottis
(c) tonsil
(d) epiglottis

Question. The structure which does not contribute to the breathing movements in mammals is
(a) larynx
(b) ribs
(c) diaphragm
(d) intercostal muscles

Question. Membrane separating air in pulmonary alveoli from blood capillaries is
(a) alveolar epithelium
(b) cardiac epithelium
(c) endothelium of blood capillaries
(d) both (a) and (c)

Question. The smallest and thinnest tube in the lung is
(a) trachea
(b) larynx
(c) bronchi
(d) bronchiole

Question. The amount of air remaining in the air passages and alveoli at the end of quiet respiration is called
(a) tidal volume
(b) inspirating reserve volume
(c) inspiratory capacity
(d) functional residual capacity

Assertion/Reason Type Questions

In the following questions, a statement of Assertion is followed by a statement of Reason.
(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
(b) If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Question. Assertion: A sigmod curve is obtained when percentage saturation of haemoglobin with O₂ is plotted against the pO₂.
Reason: Every 100 mL of oxygenated blood can deliver around 5mL of O₂ to the tissues under normal
physiological conditions.

Question. Assertion: A rise in pCO₂, H⁺ ions and temperature shifts the HbO₂ dissociation curve to right.
Reason: A rise in pCO₂ or fall in pH decreases oxygen affinity fr haemoglobin.

Matching Type Questions

Question. Match the disorders given in column – I with symptoms under column – II. Choose the answer which gives the correct combination.

Column-I (Disorders)	Column-II (Symptoms)
A. Asthma	I. Inflammation of nasal tract
B. Bronchitis	II. Spasm of bronchial muscles
C. Rhinitis	III. Fully blown out alveoli
D. Emphysema	IV. Inflammation of bronchi
	V. Cough with blood strained sputum

(a) A – IV; B – II; C – V; D – I
(b) A – V; B – III; C – II; D – I
(c) A – III; B – I; C – V; D – IV
(d) A – II; B – IV; C – I; D – III

Question. Match the column I (Organs) with column II (Functions) and choose the correct option.

Column – I (Organs)	Column – II (Functions)
A. Nose	I. Stops food from going down into lungs.
B. Epiglottis	II. Produces sound.
C. Pharynx	III. Traps bacteria as well as dust.
D. Larynx	IV. Allows air to pass from nose to oesophagus.

(a) A – II; B – III; C – I; D – IV
(b) A – III; B – I; C – IV; D – II
(c) A – I; B – IV; C – II; D – III
(d) A – IV; B – II; C – III; D – I

Critical Thinking Type Questions

Question. Oxyhaemoglobin dissociates into oxygen and deoxyhaemoglobin at
(a) low O₂ pressure in tissue.
(b) high O₂ pressure in tissue.
(c) equal O₂ pressure inside and outside tissue.
(d) all times irrespective of O₂ pressure.

Question. Dissociation curve shifts to the right when
(a) pH increases.
(b) CO₂ concentration increases.
(c) O₂ concentration decreases.
(d) 2, 3 D-P-G decreases.

Question. During oxygen transport, the oxyhaemoglobin at the tissue level liberates oxygen to the cells because in tissue
(a) O₂ concentration is high and CO₂ is low.
(b) O₂ concentration is low and CO₂ is high.
(c) O₂ tension is high and CO₂ tension is low.
(d) O₂ tension is low and CO₂ tension is high.

Question. When CO₂ concentration in blood increases, breathing becomes
(a) slow and deep.
(b) faster and deeper.
(c) shallower and slow.
(d) there is no effect on breathing.

Question. When, under certain conditions, the P₅₀ value of haemoglobin rises, the affinity of the pigment of combining with O₂ will
(a) remain same
(b) rise
(c) fall
(d) first rise and then fall

Question. Arrange the following events in the correct order as they occur during inspiration:
I. Air flows into the lungs.
II. Alveolar volume increases.
III. Thoracic volume increases.
IV. Pleural pressure decreases.
V. Alveolar pressure decreases.
(a) I – II – III – IV – V
(b) III – IV – II – V – I
(c) II – V – I – III – IV
(d) IV – V – II – I – III

Question. Vital capacity of our lungs is
(a) total lung capcity minus residual volume.
(b) inspiratory reserve volume plus tidal volume.
(c) total lung capacity minus expiratory reserve volume.
(d) inspiratory reserve volume plus expiratory reserve volume.

Question. If a person is suffering from emphysema, his/her
(a) bronchioles are found damaged.
(b) alveolar walls are found damaged.
(c) the plasma membrane is found damaged.
(d) the respiratory muscle is found damaged.

Question. Blood analysis of a patient reveals an unusually high quantity of carboxyhaemoglobin content. Which of the following conclusions is most likely to be correct? The patient has been inhaling polluted air containing usually high content of
(a) chloroform
(b) carbon dioxide
(c) carbon monoxide
(d) carbon disulphide