RBSE Class 12 Biology Chapter 23- Respiratory system in Human, provides complete information related to respiration process, types of respiration, respiratory organs, mechanism of respiration in humans, artificial respiration and respiratory disorders. It also includes a detailed study of the capacity related to the respiration process, the volume-related respiration and a lot more.
RBSE Solutions for Class 12 help students to perform their best in the exams. By practising these important questions, students can analyze their preparation, get a thorough knowledge about all the important terminologies and at the same time helps them assess their understanding of the material.
The Rajasthan Board Class 12 Biology Chapter 23 important questions are the best study material for both class assignments and other board examinations. By practising these important questions, students can gain deep knowledge about the topics explained in this chapter and also help them to be well prepared for their upcoming examinations.
RBSE Class 12 Biology Chapter 23 Important Questions
RBSE Biology Chapter 23: MCQ Type Questions
Q.1. The energy used in the process of respiration is called __________.
(a) Physical energy.
(b) Chemical energy.
(c) Kinetic energy.
(d) Electric energy.
Sol: (b) Chemical energy.
Q.2. During the process of inhalation, the diaphragm is __________.
(a) Oblique.
(b) Dome-shaped.
(c) Flattened.
(d) Normal.
Sol:(c) Flattened.
Q.3. Which of the following statements are true for the process of inhalation?
(a) The contraction of diaphragm and external intercostal muscles.
(b) The relaxation of the diaphragm and external intercostal muscles.
(c) The contraction of the only diaphragm.
(d) The relaxation of only external intercostal muscles.
Sol: (a) The contraction of the diaphragm and external intercostal muscles.
Q.4. The rate of respiration found in the resting stage of an adult is __________.
(a) 20 to 20 per minute.
(b) 18 to 20 per minute.
(c) 16 to 20 per minute.
(d) 14 to 16 per minute.
Sol: (c) 16 to 20 per minute.
Q.5. Tidal volume found in a normal man during the resting phase is __________.
(a) 1.2 litre.
(b) 0.5 litre.
(c) 2.5 litre.
(d) 4.5 litre.
Sol: (b) 0.5 litre.
Q.6.The end part of the trachea in the lung is __________.
(a) Alveoli.
(b) Bronchioles.
(c) Bronchi.
(d) Air Sac
Sol: (a) Alveoli.
Q.7.Whizzing sound during exhalation or expiration is a signal of which disease.
(a) Bronchitis.
(b) Emphysema.
(c) Silicosis.
(d) Asthma.
Sol: (d) Asthma.
Q.8. Which of the following statements are true for the process of exhalation?
(a) The contraction of diaphragm and external intercostal muscles.
(b) The relaxation of the diaphragm and external intercostal muscles.
(c) The relaxation of the diaphragm only.
(d) The contraction of external intercostal muscles.
Sol: (b) The relaxation of the diaphragm and external intercostal muscles.
Q.9. Labourers working in the mines and factories are more prone to which disease.
(a) Silicosis.
(b) Bronchitis.
(c) Emphysema.
(d) Pneumonia.
Sol: (a) Silicosis.
Q.10. The total capacity of the human lung is __________.
(a) 4600 ml.
(b) 3500 ml.
(c) 5800 ml.
(d) 2300 ml.
Sol: (c) 5800 ml.
RBSE Biology Chapter 23: Short Answer Type Questions.
Q.1. What is respiration?
Sol. Respiration is a biochemical process that occurs within the cells of all living organisms. During the process of respiration, the food molecules present within the living cells are oxidised and as a result, energy, water, and carbon dioxide (CO2) gas are produced.
Q.2.What is the respiratory surface?
Sol. The surface, which participates in the exchange of oxygen (O2) and carbon dioxide(CO2) is called the respiratory surface. An alveolus of the human lung is an example of the respiratory surface.
Q.3.What is the diaphragm? Where is the diaphragm found in the respiratory system?
Sol. A muscular, dome-shaped, membranous structure that separates the thoracic region (chest) and abdominal cavities in mammals is called the diaphragm.
In the human respiratory system, the diaphragm is present just below the lungs.
Q.4.What is breathing?
Sol. Breathing is the process of inhaling oxygen (O2) and exhaling carbon dioxide (CO2) by the lungs. There is a system of organs involved in the process.
Q.5. What is inspiration respiration?
Sol. The process of inhaling or taking in the air containing oxygen (O2) from the environment into the lungs is called inspiration or inhalation.
Q.6.What is expiration?
Sol. Expiration is the process of releasing carbon dioxide (CO2) from the body back into the atmosphere. During the process of expiration, the diaphragm relaxes and the volume of the thoracic cavity decreases and the pressure inside it increases. Consequently, the lungs contract and the air is forced out.
Q.7. What is the significance of artificial respiration?
Sol. The main significance of artificial respiration is- it is used to save the life of any person subjected to an accident such as gaseous toxicity, electric shock, drowning in water, etc. The best method of artificial respiration is mouth to mouth breathing.
Q.8. What is the expiratory reserve volume?
Sol. The expiratory reserve volume is defined as the total amount of air expired over and above the normal expiration. The volume ranges from 1000 to 1100 ml.
Q.9. What is the inspiratory reserve volume?
Sol. The inspiratory reserve volume is defined as the total amount of air inspired over and above the normal expiration. The volume ranges from 2500 to 3000 ml.
Q.10. What is residual volume?
Sol. The total amount of air that remains in a person’s lungs after the forced expiration is called the residual volume. The residual volume is measured to be in between 1100 to 1200ml.
Q.11. What is inspiratory capacity?
Sol. The inspiratory includes the tidal volume and the inspiratory reserve volume. The inspiratory capacity of humans is 3500 ml.
Q.12. What is the main function of the lungs?
Sol. The lungs are involved in the important process of breathing. The oxygen (O2) inhaled from the outside environment enters into the blood and the carbon dioxide (CO2) leaves the blood. This inhaling and exhaling are facilitated by the lungs.
Q.13. Write the names of inspiratory muscles.
Sol. External intercostal and internal intercostal muscles are two main muscles which are responsible for the forced inhalation and exhalation.
Q.14.Give any two names of respiratory disorder in humans.
Sol. Asthma and Emphysema are the two most frequently seen respiratory disorders in humans.
Q.15. What is external expiration?
Sol. The process of giving out or expelling the carbon dioxide (CO2) containing air from the lungs back into the environment is called external expiration or exhalation.
Q.16. What is the mechanism of inspiration?
Sol. Inspiration is the process of taking in the oxygen(O2) gas from the environment into the body. During the process of inspiration, contraction of the diaphragm further increases the size of the thoracic activity. Simultaneously, the lungs expand and the air pressure inside the lungs decreases. Therefore, the pressure equalizes and the atmospheric air rushes inside the lungs.
Q.17. What are respiratory organs?
Sol. The human respiratory system consists of the nostril, nasal cavity, pharynx, larynx, trachea, bronchi and lungs. Apart from these organs, alveoli are found within the lungs and function as a respiratory surface.
Q.18. What is TLC?
Sol. TLC – Total Lung capacity is the maximum amount of air that can be filled within the lungs after the maximum efforts are called the total lung capacity or TLC. The value of TLC is calculated by TLC = VC + RV. Where VC refers to the vital capacity and RV refers to residual volume. The accurate Total Lung capacity is measured to be around 5800 ml.
Q.19.What is artificial respiration?
Sol. When a person stops breathing in an accident, such as drowning, carbon monoxide (CO) or other gaseous toxicity, electrical trauma or any other conditions, but if the heart beat continues, then human life can be saved by giving artificial respiration. There are different methods of artificial respiration, the best is given based on the patient’s situation.
Q.20. Explain the passage of air during the process of inspiration.
Sol. The passage of air during the process of inspiration is as follows:
Nostril → Nasal cavity → Internal nares → Pharynx → Glottis → Trachea → Bronchi → Bronchiole → Alveolar duct → Atrium → Alveoli.
RBSE Biology Class 12: Long Answer Type Questions
Q.1.Explain the process of inspiration.
Sol. The process of inhaling or taking in the air containing oxygen (O2) from the environment into the lungs is called inspiration or inhalation.
This process involves:
- Contraction of the muscles of diaphragm.
- As a result, it moves downwards .i.e. the diaphragm becomes flat.
- There is contraction of external intercostal muscles and the relaxation of internal intercostal muscles.
- As a result, the ribs move outwards and forward.
- The above changes in the factors cause an increase in the thoracic volume but the thoracic pressure is reduced.
- Therefore, due to less pressure, the air enters into the lungs.
Q.2. What is respiration? Define external and internal respiration.
Sol. Respiration is defined as the biochemical process that occurs within the cells of all living organisms.
As our body needs the energy to perform various metabolic activities. This energy is obtained mainly by the process of oxidation of carbohydrates and fats. Oxidation of these substances consumes oxygen (O2) and releases carbon dioxide (CO2). The process of consumption of oxygen (O2) and the release of carbon dioxide (CO2) is termed as respiratory exchange.
According to Carter, the process of respiration involves external respiration, internal respiration and cellular respiration.
All mammals exhibit aerial respiration, which needs a respiratory system. The respiratory system. concerns with an intake of oxygen (O2) and giving out of carbon dioxide (CO2).
Types of Respiration.
There are two different types of respiration.
External respiration: It takes place in the lung alveoli by taking in oxygen (O2) and giving out carbon dioxide (CO2). This process is termed the external respiration or breathing or ventilation. This is a physical process.
Internal respiration: Intake of oxygen (O2) by the body cells and production of carbon dioxide (CO2) and ATP molecules is called internal respiration or cellular respiration.
The internal respiration is of two types:
Aerobic respiration: The cellular respiration, which occurs in the presence of oxygen (O2) is called aerobic respiration:
Anaerobic respiration: The cellular respiration, which occurs in the absence of oxygen (O2) is called anaerobic respiration:
Q.3. Explain the process of expiration.
Sol. Expiration is the process of releasing carbon dioxide (CO2) from the body back into the atmosphere.
This process involves :
- Relaxation of the muscles of the diaphragm.
- As a result, the diaphragm moves upwards and resumes dome shape.
- There is contraction of the internal intercostal muscles and relaxation of external intercostal muscles.
- As a result, the ribs move inwards and backwards .i.e posterior – the dorsal movement of the ribs.
- The above changes in the factors causes a decrease in the thoracic volume but the thoracic pressure is increased.
- Therefore, due to the increased pressure, air comes out of the lungs.
The breathing rate in adult human beings is 12 to 20 per minute.
Q.4. What are the main functions of the respiratory system?
Sol. The important functions of the respiratory system include-
- Vibration of vocal cords.
- Olfaction – The sense of smell.
- Inhalation and exhalation of gases.
- Exchange of gases between bloodstream and lungs.
- The gaseous exchange between bloodstream and body tissues.
Q.5. Draw a neat labelled diagram explaining the mechanism of respiration.
Sol.
Q.6. Write the difference between internal respiration and external respiration.
Sol. The difference between internal respiration and external respiration are:
| Internal respiration | External respiration |
| Occurs only in the living cells. | Occurs between the living cells and the external environment. |
| Does not involve breathing. | Involves breathing. |
| Oxygen is not attached to the heme. | Oxygen is attached to heme. |
| Occurs in the absence of oxygen. | Occurs only during the presence of oxygen |
| Does not involve gaseous exchange. | Involves gaseous exchange. |
| Water is formed by the combination of oxygen with protons. | Oxyhemoglobin is formed by the combination of oxygen with hemoglobin |
Q.7. Explain the process of artificial respiration.
Sol. During accidental conditions of a person, such as gaseous toxicity or carbon monoxide effects, electric shock, drowning in water, etc, if the breathing stops and heartbeats continue, then the human life can be saved by giving artificial respiration.
Normally artificial respiration activates the respiratory centres, hence normal breathing can be restored.
There are many methods of artificial respiration. Among all of them, “Mouth to Mouth technique” is the best and the most effective method.
Following are the main steps involved in the process of artificial respiration:
- Keep the patient on a hard bed, lying in a straight position. Place one of your one hands on the patient’s head and another hand should be below the patient’s head.
- This helps in the opening of the respiratory passage.
- Close the nose of the patient with the same hand, which is on the patient’s head and bring your mouth close to the patient’s mouth in such a way that an airtight position is formed.
- The hand below the head is to remain as such, so that the neck remains stretched.
- Push air into the mouth of a patient forcefully about 10 to 12 times of tidal volume (500ml)
- This helps in the opening of the patient’s nose and mouth and allows expiration.
Q.8. What is Emphysema disease? How can it be prevented?
Sol. Emphysema is a disease caused due to heavy smoking and side effects from the air pollution. Smoking causes continuous stimulation in the lungs, which destroys the alveolar walls. This results in an increased air space but decreases the respiratory surface in the lungs.
Lung elasticity is also reduced due to the increased amount of the connective tissues. It causes difficulties in expiration.
This disease can be prevented by avoiding exposure to the air pollution. Quitting smoking also helps in preventing this disease. Emphysema can also be cured and prevented by regular use of antibiotics and bronchodilators.
Q.9. Draw the diagram of the human lungs.
Sol. 
Q.10. What is respiration? Why do we Respire?
Sol. Respiration is an essential biochemical process that occurs within the cells of all living organisms. During the process of respiration, the food molecules present within the living cells are oxidised and as a result, energy, water, and carbon dioxide (CO2) gas are produced. We humans have developed a complex respiratory system consisting of different organs for inhaling oxygen and exhaling carbon dioxide. The major organs of human respiratory system are as follows:
- Nose and nasal cavity or Nostrils.
- Pharynx
- Larynx.
- Trachea
- Bronchioles.
- Lungs.
Every living organism requires energy for their survival. Even when we are eating or sleeping, we need energy. Respiration is the process through which the food which we eat is converted into valuable energy. Every single cell requires energy to perform their functions.
While breathing, we breathe in air that contains oxygen and we breathe out air rich in carbon dioxide. As we breathe in, the oxygen-rich air is transported to all parts of our body and ultimately to each cell. Inside the cell, the food, which contains glucose, is broken down into carbon dioxide and water with the help of oxygen. The process of breakdown of glucose to release energy, which can be utilized by our body to perform daily chores like walking, sitting or even thinking, is known as respiration.
Q.11. Write a short note on respiratory disorders.
Sol. Respiratory disorders are diseases of lungs and human airways that affect human respiration. This results in the irregular functioning of the body. There are various types of respiratory diseases, the most common types are:
Asthma.
It is a respiratory disease, in which a person’s air passage becomes inflamed, narrow, swells, and produces more mucus, which makes it difficult to breathe.
Causes: This disease is mainly caused by several factors including the pollen, dust particles, cold, smoking, etc.
Symptoms: This causes difficulty in breathing, chest pain, coughing and wheezing.
Treatment: Asthma can be treated by rescue inhalers, antibiotics and other vaccinations.
Precaution: The best remedy to prevent asthma is to stay away from the allergens and other triggering factors.
Bronchitis.
This disease involves the inflammation of the lining of bronchial tubes, which carry air to and fro from the lungs.
Causes: Smoking, passive smoking, exposure to pollution and other bacterial infections.
Symptoms: Swelling on the internal lining of bronchitis that causes constant coughing. The bronchitis may either be acute or chronic.
Treatment: Use of antibiotics, other medication and lifestyle changes.
Precaution: Avoid smoking and be less exposed to pollution.
Emphysema.
Emphysema is defined as the chronic disease reduction of the respiratory surface due to the damage to the lung alveolar walls.
Causes: Mainly caused by smoking cigarettes and other tobacco products. Other causes include inhalation of Chemicals, toxins, dust and exposure to smoke.
Symptoms: The main symptoms of emphysema include shortness of breath and cough. Emphysema might lead to a loss of elasticity of the lungs.
Treatment: Use of certain antibiotics and bronchodilators are helpful to get rid of these respiratory disorders.
Precaution: Avoid smoking and changes in the lifestyle.
Lung cancer.
Lung cancer can develop in any part of the lungs. It occurs in the main part of the lungs.
Causes: Smoking, exposure to asbestos fibers, rubber, toxic gases, traffic fumes, etc.
Symptoms: Difficulty in breathing, wheezing, trouble during swallowing, chest pain, etc.
Treatment: Surgery, Chemotherapy, Radiation Therapy, etc.
Precaution: Avoid smoking and exposure to pollution and other toxic gases.
Pneumonia
It is a serious infection of the lungs, which affects people with weakened immune systems including infants, young children and old people.
Causes: Caused by various pathogenic bacteria, viruses and fungi.
Symptoms: Shortness of breath, Chest pain, Cough, Nausea, etc.
Treatment: Use of certain antibiotics and Vaccinations for infants and children.
Precaution: Maintain hygiene, avoid smoking and alcohol consumption, Maintain strong immunity by having a well balanced diet.
Q.12. Write a short note on volume related to respiration.
Sol. The volume related to respiration is called the Lung volume or the lung capacities. The volume related to respiration mainly refers to the total volume of air present in the lungs during the different phases of the respiration process.
The different types of volume related to respiration are:
- Tidal Volume
The total volume of air inhaled into the lungs during inspiration and exhaled out during expiration during the process of normal breathing is called the tidal volume (TV).
In each breath, the measurement of tidal volume in inspiration or expiration is 500ml. A healthy man can inspire or expire at the rate of 6000 to 8000ml air per minute.
- Inspiratory Reserve Volume.
The extra quantity of air volume can be inspired forcefully by a person. The average Inspiratory Reserve Volume (IRV) should be in between 2500ml to 3000ml.
- Expiratory Reserve Volume.
The extra quantity of air volume that can be expired forcefully by a person. The average Expiratory Reserve Volume (ERV) should be in between 1000ml and 1100ml.
- Reserve Volume.
The volume of air, which remains in the lungs after a force full of expiration is called the reserve volume. It should be in between 1100ml and 1200ml.
Q.13. Describe the human respiratory organs.
Sol. The respiratory passage of human includes following organs:
Nostrils:
The nose possesses a couple of exterior nostrils which are divided by a framework of cartilaginous structure termed as the septum. This is the structure that evenly separates the right nostril from the left nostril. Tiny hair follicles that cover the interior lining of nostrils acts as the body’s first line of defence against foreign pathogens. Furthermore, they provide additional humidity for inhaled air.
Larynx
Two cartilaginous chords lay the framework for the larynx. They are situated at the point of joining the pharynx and trachea. It is also termed as Adam’s apple or the voice box. It is the portion which rises and falls during swallowing of food particles. It generates sound as air passes through the hollow in the middle.
Pharynx
The nasal chambers open up into a wide hollow space termed as the pharynx. It is a common path for both air and food. It functions by preventing the entry of food particles into the windpipe. The epiglottis is elastic cartilage, which serves as a switch between the larynx and the oesophagus by allowing the passage of air into the airway to the lungs, and food into the gastrointestinal tract.
Trachea
The trachea or the windpipe rises below the larynx and moves down to the neck. The walls of trachea comprise C-shaped cartilaginous rings, which give hardness to the trachea and maintain it by completely expanding. The trachea extends further down into the breastbone and splits into two bronchi, one for each lung.
Bronchi
The trachea splits into two tubes termed as bronchi, which enter each lung individually. The bronchi are divided into secondary, tertiary, and bronchioles which are again further divided into small air-sacs called the alveoli. The alveoli are minute sacs of air with thin walls, and single-celled manner. It enables the exchange of oxygen and carbon dioxide molecules into or away from the bloodstream.
Lungs
Lungs are the chief centres of respiration in humans and other vertebrates. They are located in the thoracic cavity of the chest near the backbone and on either side of the heart. They are the pair of large, spongy organs mainly involved in the exchange of gases between the blood and the air. Compared to the left lung, the right lung is quite bigger and heavier.
Q.14.Draw the diagram of the human respiratory system.
Sol.The diagram of the human respiratory system shows different parts involved in the exchange of gases.
Q.15. Write a short note on capacities related to respiration.
Sol. Capacities are measurements of two or more volumes. The average total lung capacity of an adult human male is about 6 litres of air. The different types of the capacities related to respiration are:
- Inspiratory Capacity.
The maximum quantity of air, which can be taken during the process of inspiration is called the Inspiratory Capacity. This is equal to the sum of tidal volume and the inspiratory reserve volume.
IC = TV + IRV
- Expiratory Capacity.
The maximum quantity of air, which can be exhaled out during the process of respiration is called the Expiratory Capacity. It includes tidal volume and the expiratory reserve volume.
EC = TV + ERV.
- Functional Residual Capacity.
The amount of air which remains in lungs after a normal breathing is called the Functional Residual Capacity. It includes expiratory reserve volume and reserve volume .
FRC =ERV + RV.
The Functional Residual Capacity Is about 2300ml.
- Vital Capacity.
The maximum air inhaled and exhaled by the lungs is called the vital capacity .
VC = IRV + TV + ERV.
The Vital Capacity is about 4600ml.
- Total Lung Capacity.
The maximum amount of air that can be filled in the lungs after the maximum efforts is called the Total Lung Capacity (TLC).
The TLC value is calculated by TLC = VC + RV.
The Total Lung Capacity is about 5800ml.
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