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NCERT Solutions Class 11 Biology Chapter 14 - Breathing and Exchange of Gases
NCERT Solutions for Class 11 Biology Chapter 14 (Breathing and Exchange of Gases) explain how the human body takes in oxygen and removes carbon dioxide produced during cellular respiration. This chapter introduces important topics of human physiology, including the respiratory system, mechanism of breathing, exchange of gases, transport of oxygen and carbon dioxide, and regulation of respiration. Students can learn how the respiratory system helps supply oxygen to tissues and remove carbon dioxide from the body.
NCERT Solutions for Class 11 Biology Chapter 14 by ALLEN gives detailed explanations for changes in pressure during breathing, exchange of gases in lungs and tissues and role of haemoglobin in transport of oxygen. The chapter also discusses respiratory volumes and capabilities, the oxygen-haemoglobin dissociation curve, transport of carbon dioxide and the management of breathing. These solutions allow kids to learn the important concepts of NCERT and prepare for the School examinations and NEET.
1.0Class 11 Biology Chapter 14 Breathing and Exchange of Gases: Key Concepts
Class 11 Biology Chapter 14, Breathing and Exchange of Gases, explains how humans take in oxygen and remove carbon dioxide from the body. The chapter covers the respiratory system, breathing mechanism, exchange and transport of gases, regulation of respiration, and common respiratory disorders.
- Respiratory Organs: Learn about respiratory structures such as gills, trachea, and lungs found in different animals.
- Mechanism of Breathing: Understand inspiration and expiration and how the diaphragm and intercostal muscles help in the process.
- Respiratory Volumes and Capacities: Learn about Tidal Volume (TV), Inspiratory Reserve Volume (IRV), Vital Capacity (VC), Total Lung Capacity (TLC), and other important lung measurements.
- Exchange of Gases: Understand how oxygen and carbon dioxide are exchanged between the alveoli and blood through diffusion based on differences in partial pressure.
- Transport of Gases: Learn how oxygen is transported mainly by haemoglobin and how factors such as pH, temperature, and carbon dioxide concentration affect oxygen transport.
- Regulation of Respiration: Understand the role of the respiratory rhythm centre in the medulla and the pneumotaxic centre in the pons in controlling breathing.
- Disorders of the Respiratory System: Study common respiratory disorders such as asthma, emphysema, silicosis, and asbestosis.
2.0Detailed NCERT Textbook Solutions : Class 11 Biology Chapter 14
- Define vital capacity. What is its significance? Ans. Vital capacity is defined as the maximum volume of air a person can breathe in after a forced expiration this includes ERV, TV and IRV or the maximum volume of air a person can breathe out after a forced inspiration. Represents the maximum amount of air one can renew in the respiratory system in a single respiration. Thus, greater the vital capacity more is the energy available to the body.
- State the volume of air remaining in the lungs after a normal breathing. Ans. When a person breathes normally, the amount which remains in the lung after normal expiration, is called functional residual capacity. It is the sum of residual volume and the expiratory reserve volume (FRC = RV + ERV). It is about 2100-2300 mL of air.
- Diffusion of gases occurs in the alveolar region only and not in the other parts of respiratory system. Why? Ans. The diffusion membrane is made up of three major layers namely
- The thin squamous epithelium of alveoli.
- The endothelium of alveolar capillaries and the basement substance in between them. However, its total thickness is much less than a millimetre. Therefore, all the factors in our body are favourable for diffusion of from alveoli to tissues and that of from tissues to alveoli.
- What are the major transport mechanisms for ? Explain. Ans. Transport of Carbon dioxide : is carried by haemoglobin as carbamino-haemoglobin (about 20-25 per cent). This binding is related to the partial pressure of . is a major factor which could affect this binding. When is high and is low as in the tissues, more binding of carbon dioxide occurs whereas, when the is low and is high as in the alveoli, dissociation of from carbamino-haemoglobin takes place, i.e., which is bound to haemoglobin from the tissues is delivered at the alveoli. RBCs contain a very high concentration of the enzyme, carbonic anhydrase and minute quantities of the same is present in the plasma too. This enzyme facilitates the following reaction in both directions. At the tissue site where partial pressure of is high due to catabolism, diffuses into blood (RBCs and plasma) and forms and H+,. At the alveolar site where is low, the reaction proceeds in the opposite direction leading to the formation of and . Thus, trapped as bicarbonate at the tissue level and transported to the alveoli is released out as .
- What will be the and in the atmospheric air compared to those in the alveolar air? (i) lesser, higher (ii) higher, lesser (iii) higher, higher (iv) lesser, lesser
Ans. higher, lesser
(ii) Air that has entered the alveoli through the bronchioles is called alveolar air. It has the same partial pressure of and as is in the atmospheric air. Then, there occurs gaseous exchange between the adjacent blood capillaries and the alveoli. diffuses from blood into the alveolar air and diffuses from alveolar air to the blood. As a result, new alveolar air has higher and lesser , than the atmospheric air.
- Explain the process of inspiration under normal conditions. Ans. Inspiration during which atmospheric air is drawn in The movement of air into and out of the lungs is carried out by creating a pressure gradient between the lungs and the atmosphere. Inspiration can occur if the pressure within the lungs (intra-pulmonary pressure) is less than the atmospheric pressure, i.e., there is a negative pressure in the lungs with respect to atmospheric pressure. Similarly, expiration takes place when the intra-pulmonary pressure is higher than the atmospheric pressure. The diaphragm and a specialised set of muscles - external and internal intercostals between the ribs, help in generation of such gradients. Inspiration is initiated by the contraction of diaphragm which increases the volume of thoracic chamber in the antero-posterior axis. The contraction of external inter-costal muscles lifts up the ribs and the sternum causing an increase in the volume of the thoracic chamber in the dorso-ventral axis. The overall increase in the thoracic volume causes a similar increase in pulmonary volume. A n increase in pulmonary volume decreases the intrapulmonary pressure to less than the atmospheric pressure which forces the air from outside to move into the lungs, i.e., inspiration.
- How is respiration regulated? Ans. Human beings have a significant ability to maintain and moderate the respiratory rhythm to suit the demands of the body tissues. This is done by the neural system. A specialised centre present in the medulla region of the brain called respiratory rhythm centre is primarily responsible for this regulation. Another centre present in the pons region of the brain called pneumotaxic centre can moderate the functions of the respiratory rhythm centre. Neural signal from this centre can reduce the duration of inspiration and thereby alter the respiratory rate. A chemosensitive area is situated adjacent to the rhythm centre which is highly sensitive to and hydrogen ions. Increase in these substances can activate this centre, which in turn can signal the rhythm centre to make necessary adjustments in the respiratory process by which these substances can be eliminated. Receptors associated with aortic arch and carotid artery also can recognise changes in CO2 and H+ concentration and send necessary signals to the rhythm centre for remedial actions.
- What is the effect of on oxygen transport? Ans. Increase in tension in blood brings rightward shift of the oxygen dissociation curve of hemoglobin thereby decreasing the affinity of hemoglobin for oxygen. This effect is called Bohr's effect. It plays an important role in the release of oxygen in the tissues.
- What happens to the respiratory process in a man going up a hill? Ans. Rate of breathing will increase in order to supply sufficient oxygen to blood because air in mountainous region is deficient in oxygen.
- What is the site of gaseous exchange in an insect? Ans. Tracheae (Tracheal respiration) is the site of gaseous exchange in an insect.
- Define oxygen dissociation curve. Can you suggest any reason for its sigmoidal pattern? Ans. Each haemoglobin molecule can carry a maximum of four molecules of . Binding of oxygen with haemoglobin is primarily related to partial pressure of . Partial pressure of , hydrogen ion concentration and temperature are the other factors which can interfere with this binding. A sigmoid curve is obtained when percentage saturation of haemoglobin with is plotted against the . This curve is called the Oxygen dissociation curve (Figure) and is highly useful in studying the effect of factors like concentration, etc., on binding of with haemoglobin. In the alveoli, where there is high , low , lesser H+ concentration and lower temperature, the factors are all favourable for the formation of oxyhaemoglobin, whereas in the tissues, where low , high , high concentration and higher temperature exist, the conditions are favourable for dissociation of oxygen from the oxyhaemoglobin. This clearly indicates that gets bound to haemoglobin in the lung surface and gets dissociated at the tissues.
- Have you heard about hypoxia? Try to gather information about it, and discuss with your friends. Ans. Hypoxia is a condition of oxygen shortage in the tissues. It is of two types: (i) Artificial hypoxia: It results from shortage of oxygen in the air as at high altitude. It causes mountain sickness characterised by breathelessnes, headache, dizziness and bluish tinge on skin. (ii) Anaemic hypoxia: It results from the reduced oxygen carrying capacity of the blood due to anaemia or carbon monoxide poisoning. In both cases, less haemoglobin is available for carrying .
- Distinguish between (a) IRV and ERV (b) Inspiratory capacity and expiratory capacity. (c) Vital capacity and total lung capacity.
Ans.
(a) Differences between IRV and ERV are as follows:
(b) Differences between inspiratory capacity and expiratory capacity are as follows:
(c) Differences between vital capacity and total lung capacity are as follows:
- What is tidal volume? Find out the tidal volume (approximate value) for a healthy human in an hour. Ans. Tidal volume is the volume of air inspired or expired with each normal breath. This is about 500 mL in an adult person. It is composed of about 350 mL of alveolar volume and about 150 mL of dead space volume. The alveolar volume consists of air that reaches the respiratory surfaces of the alveoli and engages in gas exchange. The dead space volume consists of air that does not reach the respiratory surfaces. A healthy man can inspire or expire approximately 6000 to 8000 mL of air per minute. Therefore, tidal volume for a healthy human in an hour is 360-480 mL of air.
3.0NCERT Class 11 Biology – Chapter-Wise Solutions & Explanations
Study Class 11 Biology with chapter-wise NCERT Solutions and answers to all textbook questions. Understand important concepts, revise key topics, and prepare well for your Biology exams.
4.0Key Features of NCERT Solutions for Class 11 Biology Chapter 14
- Partial Pressure of Gases: Understand the partial pressure of oxygen and carbon dioxide in the alveoli, blood, and tissues and how these differences help in the exchange of gases.
- Oxygen Dissociation Curve: Learn about the sigmoid oxygen dissociation curve and how changes in pH, carbon dioxide concentration, and other factors affect the binding of oxygen with haemoglobin.
- Transport of Carbon Dioxide: Understand how carbon dioxide is transported in the blood, including its conversion into bicarbonate ions inside red blood cells with the help of carbonic anhydrase.
- Respiratory Volume and Capacity Calculations: Learn the formulas and calculations related to tidal volume, vital capacity, total lung capacity, and other respiratory volumes.
- Prepared by ALLEN Expert Faculty: Get clear explanations of the topics covered in NCERT Class 11 Biology Chapter 14, including breathing, gas exchange, gas transport, and regulation of respiration.
- Respiratory Disorders: Understand the causes and effects of respiratory disorders such as asthma, emphysema, silicosis, and asbestosis.
- Complete NCERT Exercise Solutions: Get clear answers to NCERT exercise questions to revise important concepts from Breathing and Exchange of Gases and prepare for school exams and NEET.