Read and download the CBSE Class 11 Biology Breathing and Exchange of Gases Assignments for the 2025-26 academic session. We have provided comprehensive Class 11 Biology school assignments that have important solved questions and answers for Chapter 14 Breathing And Exchange Of Gases. These resources have been carefuly prepared by expert teachers as per the latest NCERT, CBSE, and KVS syllabus guidelines.
Solved Assignment for Class 11 Biology Chapter 14 Breathing And Exchange Of Gases
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Chapter 14 Breathing And Exchange Of Gases Class 11 Solved Questions and Answers
Question. Lungs are enclosed in
(a) periosteum
(b) perichondrium
(c) pericardium
(d) pleural membrane.
Answer. D
Question. The presence of CO2 in blood will lower pH because CO2 combines with____, with the rate of reaction increased by_____ .
(a) H2O to form H+ and HCO3–, carbonic anhydrase
(b) H2O to form only HCO3–, carbonic anhydrase
(c) H2O to form only H+, carbonic ions
(d) H+ to form HCO3–, oxyhaemoglobin
Answer. A
Question. Skin is an accessory organ of respiration in
(a) humans
(b) frog
(c) rabbit
(d) lizard.
Answer. B
Question. Select the correct events that occur during inspiration.
(1) Contraction of diaphragm
(2) Contraction of external inter-costal muscles
(3) Pulmonary volume decreases
(4) Intra pulmonary pressure increases
(a) (1) and (2)
(b) (3) and (4)
(c) (1), (2) and (4)
(d) only (4)
Answer. A
Question. Tidal volume and expiratory reserve volume of an athlete is 500 mL and 1000 mL respectively. What will be his expiratory capacity if the residual volume is 1200 mL?
(a) 2700 mL
(b) 1500 mL
(c) 1700 mL
(d) 2200 mL
Answer. B
Question. Oxidative breakdown of respiratory substrates with the help of O2 is called as
(a) fermentation
(b) anaerobic respiration
(c) R. Q.
(d) aerobic respiration
Answer. D
Question. Severe Acute Respiratory Syndrome (SARS)
(a) is caused by a variant of Pneumococcus pneumoniae.
(b) is caused by a variant of the common cold virus (corona virus).
(c) is an acute form of asthma.
(d) affects non-vegetarians much faster than the vegetarians.
Answer. B
Question. Select the correct statement.
(a) Expiration occurs due to external intercostal muscles.
(b) Intrapulmonary pressure is lower than the atmospheric pressure during inspiration.
(c) Inspiration occurs when atmospheric pressure is less than intrapulmonary pressure.
(d) Expiration is initiated due to contraction of diaphragm.
Answer. B
Question. Match the items given in column I with those in column II and select the correct option given below.
Column I Column II
(A) Tidal volume (i) 2500 – 3000 mL
(B) Inspiratory reserve (ii) 1100 – 1200 mL volume
(C) Expiratory reserve (iii) 500 – 550 mL volume
(D) Residual volume (iv) 1000 – 1100 mL
(A) (B) (C) (D)
(a) (iii) (ii) (i) (iv)
(b) (iii) (i) (iv) (ii)
(c) (i) (iv) (ii) (iii)
(d) (iv) (iii) (ii) (i)
Answer. B
Question. Lungs are made up of air-filled sacs, the alveoli. They do not collapse even after forceful expiration, because of
(a) inspiratory reserve volume
(b) tidal volume
(c) expiratory reserve volume
(d) residual volume.
Answer. D
Question. Lungs do not collapse between breaths and some air always remains in the lungs which can never be expelled because
(a) there is a negative pressure in the lungs
(b) there is a negative intrapleural pressure pulling at the lung walls
(c) there is a positive intrapleural pressure
(d) pressure in the lungs is higher than the atmospheric pressure.
Answer. B
Question. Which one of the following is a possibility for most of us in regard to breathing, by making a conscious effort?
(a) One can breathe out air totally without oxygen.
(b) One can breathe out air through Eustachian tube by closing both nose and mouth.
(c) One can consciously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all.
(d) The lungs can be made fully empty by forcefully breathing out all air from them.
Answer. B
Question. Listed below are four respiratory capacities (i–iv) and four jumbled respiratory volumes of a normal human adult.
Respiratory capacities Respiratory volumes
(i) Residual volume 2500 mL
(ii) Vital capacity 3500 mL
(iii) Inspiratory reserve volume 1200 mL
(iv) Inspiratory capacity 4500 mL
Which one of the following is the correct matching of two capacities and volumes?
(a) (ii) 2500 mL, (iii) 4500 mL
(b) (iii) 1200 mL, (iv) 2500 mL
(c) (iv) 3500 mL, (i) 1200 mL
(d) (i) 4500 mL, (ii) 3500 mL
Answer. C
Question. What is vital capacity of our lungs?
(a) Inspiratory reserve volume plus expiratory reserve volume
(b) Total lung capacity minus residual volume
(c) Inspiratory reserve volume plus tidal volume
(d) Total lung capacity minus expiratory reserve volume
Answer. B
Question. Which one of the following statements is incorrect?
(a) The principle of countercurrent flow facilitates efficient respiration in gills of fishes.
(b) The residual air in lungs slightly decreases the efficiency of respiration in mammals.
(c) The presence of non-respiratory air sacs, increases the efficiency of respiration in birds.
(d) In insects, circulating body fluids serve to distribute oxygen to tissues.
Answer. B
Question. When 1500 mL air is in the lungs, it is called
(a) residual volume
(b) inspiratory reserve volume
(c) vital capacity
(d) tidal volume.
Answer. A
Question. The ventilation movements of the lungs in mammals are governed by
(a) muscular walls of lung
(b) diaphragm
(c) intercostal muscles
(d) both (b) and (c).
Answer. D
Question. In man and mammals, air passes from outside into the lungs through
(a) nasal cavity, larynx, pharynx, trachea, bronchi, alveoli
(b) nasal cavity, larynx, pharynx, trachea, bronchioles, alveoli
(c) nasal cavity, pharynx, larynx, trachea, bronchioles, bronchi, alveoli
(d) nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli.
Answer. D
Solve the MCQ questions below
| Option | Meaning |
| (1) A | Both Assertion and Reason are true, and the Reason is the correct explanation for the Assertion. |
| (2) B | Both Assertion and Reason are true, but the Reason is NOT the correct explanation for the Assertion. |
| (3) C | The Assertion is true, but the Reason is false. |
| (4) D | Both the Assertion and the Reason are false. |
Question. Assertion :- Primary bronchi branches to form secondary bronchi.
Reason :- Diameter of primary bronchi is greater than secondary bronchi.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. Assertion :- Tracheal cartilaginous rings are incomplete dorsally.
Reason :- Complete rings would obstruct oesophagus.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- Any change in volume of thoracic cavity reflects on pulmonary volume.
Reason :- Parietal pleura is closely connected to rib cage.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- Lungs expand due to filling up of air in them.
Reason :- Internal intercostal muscles help in this expansion.
(a) A
(b) B
(c) C
(d) D
Answer: D
Question. Assertion :- Residual volume is excluded in vital capacity.
Reason :- Residual volume can't be measured by spirometer.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. 6. Assertion :- Solubility of the gases can affect the rate of diffusion.
Reason :- Thickness of the membrane involved in diffusion can also affect the rate of diffusion.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. Assertion :- 3% of \( \text{O}_2 \) is transported in dissolved state.
Reason :- 97 percent of \( \text{O}_2 \) is transported via RBC's.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. Assertion :- Oxygen dissociation curve is sigmoidal in shape.
Reason :- Binding of \( \text{O}_2 \) with Hb increases Hb's affinity towards \( \text{O}_2 \).
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- \( \text{HCO}_3^– \) diffuses into plasma and \( \text{Cl}^– \) diffuses into erythrocytes.
Reason :- This exchange balances charges on both sides.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- Pneumotaxic centre increases the duration of inspiration.
Reason :- It sends singnals to intercostal muscles.
(a) A
(b) B
(c) C
(d) D
Answer: D
Question. Assertion :- Diffusion membrane is made of three major layers.
Reason :- The layers are alveolar epithelium, Endothelium of blood capillary and basement membrane between them.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- \( \text{O}_3 \) reacts with Hb to form methemoglobin.
Reason :- \( \text{O}_3 \) gets oxidised in this process.
(a) A
(b) B
(c) C
(d) D
Answer: C
Question. Assertion :- Volume of air present in conducting zone is dead space volume.
Reason :- It averages around 150 ml in humans.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. Assertion :- Breathing stops during swallowing of food.
Reason :- Gullet is dorsal to Glottis.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. Assertion :- Expiration is not always a passive process.
Reason :- Internal intercostal muscles and abdominal muscles are involved in forceful expiration.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- Mechanism of breathing vary among different groups of animals.
Reason :- It vary mainly due to their habitats and level of organisation.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- Fishes use gills for respiration.
Reason :- Gills are special vascularised structures.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. Assertion :- Amphibians like frog can respire through their skin.
Reason :- Skin of frog moist, glandular and highly vascular.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- Larynx is called sound box.
Reason :- It is a cartilaginous box which help in sound production.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- The wall of trachea, primary secondary and tertiary bronchi and initial bronchioles is non-collapsible.
Reason :- Their wall is supported by incomplete cartilaginous rings.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- Lungs are covered by a double layered pleura.
Reason :- Lungs are located in thoracic cavity.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. Assertion :- Alveoli and their ducts form the respiratory or exchange part of the respiratory system.
Reason :- These are the site of actual diffusion of \( \text{O}_2 \) and \( \text{CO}_2 \) between blood and atmospheric air.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- Diaphragm and external intercostal muscles are inspiratory muscles.
Reason :- Whenever these muscles relaxed result into expiration.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. Assertion :- Volume of air inspired or expired during a normal respiration is called tidal volume.
Reason :- Additional volume of air, a person can inspire by a normal inspiration is called as IRV (Inspiratory reserve volume).
(a) A
(b) B
(c) C
(d) D
Answer: C
Question. Assertion :- Alveoli are the primary site of exchange of gases.
Reason :- Exchange of gases also occur between blood and tissue.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. Assertion :- Pressure contributed by an individual gas in a mixture of gases is called partial presure.
Reason :- Partial pressure of \( \text{O}_2 \) in alveoli is 104 mmHg.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. Assertion :- The amount of \( \text{CO}_2 \) that can diffuse through diffusion membrane per unit difference in partial pressure is much higher compared to that of \( \text{O}_2 \).
Reason :- Solubility of \( \text{CO}_2 \) is 20-25 times higher than that of \( \text{O}_2 \).
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- Blood is the medium of transport for \( \text{O}_2 \) and \( \text{CO}_2 \) in human.
Reason :- 100% \( \text{O}_2 \) and 100% \( \text{CO}_2 \) is transported by blood in human.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- Each haemoglobin molecule can carry a maximum of four molecules of \( \text{O}_2 \).
Reason :- Each haemoglobin molecule has 4 globin chains 4 heme part and 4 iron atom.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- At the tissue site partial pressure of \( \text{CO}_2 \) is high.
Reason :- It is due to catabolism.
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- Every 1000 ml of deoxygenated blood delivers approximately 40 ml of \( \text{CO}_2 \) to the alveoli.
Reason :- Every 1000 ml of oxygenated blood can deliver around 50 ml of \( \text{O}_2 \) to the tissue under normal physiological conditions.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. Assertion :- Emphysema is a chronic disorder in which alveolar wall are damaged.
Reason :- It is due to hypoactivity of elastase enzyme.
(a) A
(b) B
(c) C
(d) D
Answer: C
Question. Assertion :- Central chemoreceptors are highly sensitive to \( \text{CO}_2 \) and \( \text{H}^+ \) ions.
Reason :- Central chemoreceptors is situated adjacent to the rhythm centre.
(a) A
(b) B
(c) C
(d) D
Answer: B
Question. Assertion :- The role of oxygen in the regulation of respiraotry rhythm is quite insignificant.
Reason :- Central and peripheral chemoreceptor highly sensitive to changes in \( \text{CO}_2 \) and \( \text{H}^+ \) ions not \( \text{O}_2 \).
(a) A
(b) B
(c) C
(d) D
Answer: A
Question. Assertion :- A pneumotaxic centre in the pons region of the brain can alter respiratory mechanism.
Reason :- Apnestic centre present in pons.
(a) A
(b) B
(c) C
(d) D
Answer: B
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CBSE Class 11 Biology Chapter 14 Breathing And Exchange Of Gases Assignment
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