In This Post we are  providing Chapter-17 Breathing and Exchange of Gases NCERT MCQ for Class 11 Biology which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MCQ ON BREATHING AND EXCHANGE OF GASES

Question 1 : When CO₂ concentration in blood increases, breathing becomes

• a) faster and deeper
• b) slow and deep
• c) there is no effect on breathing
• d) shallower and slow

Answer : faster and deeper

Question 2 : The largest quantity of air that can be expired after a maximal inspiratory effort is called

• a) vital capacity
• b) residual volume
• c) tidal volume
• d) total lung volume

Answer : vital capacity

Question 3 : Which one of the following statements is incorrect ?

• a) In insects, circulating body fluids serve to distribute oxygen to tissues
• b) The principle of counter current flow facilitates efficient respiration in gills of fishes
• c) The residual air in lungs slightly decreases the efficiency of respriration in mammals.
• d) None of these

Answer : In insects, circulating body fluids serve to distribute oxygen to tissues

Question 4 : Emphysema develops mainly because of

• a) Spasm of the smooth muscles of bronchioles
• b) Cigarette smoking
• c) Inflammation of the alveoli
• d) Allergy or hypersensitisation

Answer : Spasm of the smooth muscles of bronchioles

Question 5 : During inspiration the diaphragm

• a) contracts and flattens
• b) relaxes to become dome-shaped
• c) shows no change
• d) None of these

Answer : contracts and flattens

Question 6 : The volume of air breathed in and out during normal breathing is called

• a) Tidal volume
• b) Explratory reserve volume
• c) Vital capacity
• d) None of these

Answer : Tidal volume

Question 7 : What would happen if human blood becomes acidic (low pH)

• a) Oxygen carrying capacity of haemoglobin decreases
• b) RBCs count increases
• c) RBCs count decreases
• d) Oxygen carying capacity of haemoglobin increases

Answer : Oxygen carrying capacity of hemoglobin decreases

Question 8 : Even when there is no air in it, human trachea does not collapse due to presence of

• a) Cartilaginous rings
• b) Turgid pressure
• c) Bony rings
• d) Chitinous rings

Answer : Cartilaginous rings

Question 9 : The structure which does not contribute to the breathing movements in mammals is

• a) Larynx
• b) Diaphragm
• c) Ribs
• d) Intercostal muscles

Answer : Larynx

Question 10 : In emphysema

• a) Gas exchange area of lungs is reduced
• b) Gas exchange area of lungs is increased
• c) Trachea gets narrowed
• d) Larynx is permanently closed

Answer : Gas exchange area of lungs is reduced

Question 11 : Which of the following changes occur in diaphragm and intercostal muscles when expiration of air takes place?

• a) External intercostal muscles and diaphargm relax
• b) External intercostal muscles and diaphargm contract
• c) External intercostal muscles contract and diaphargm relaxes
• d) External intercostal muscles relax and diaphargm contracts

Answer : External intercostal muscles and diaphragm relax

Question 12 : When you exhale, the diaphragm

• a) relaxes and arches
• b) relaxes and flattens.
• c) contracts and arches
• d) contracts and flattens

Answer : relaxes and arches

Question 13 : Smoking destroys the cilia in the respiratory passageways. This

• a) makes it harder to keep the lungs clean
• b) slows blood flow through lung blood vessels
• c) decreases the surface area for respiration.
• d) makes it harder to move air in and out of the lungs

Answer : makes it harder to keep the lungs clean

Question 14: Gas flows into the lungs of mammals during inspiration because

• a) The pressure in the lungs falls below atmospheric pressure
• b) The pressure in the lungs rises above atmospheric pressure.
• c) The volume of the lungs decreases
• d) The diaphragm moves upward toward the lungs

Answer : The pressure in the lungs falls below atmospheric pressure

Question 15 : The function of the mucus elevator in the mammalian respiratory system is to

• a) trap and remove particulate matter that has entered the respiratory system.
• b) stimulate contraction of rib musculature during forcible exhalation
• c) produce negative pressure during inhalation
• d) move surfactant from the bronchi to the alveoli

Answer : trap and remove particulate matter that has entered the respiratory system.