RBSE Solutions Class 12 Biology Chapter 23 Man-Respiratory System

RBSE Class 12 Biology Chapter 23 Multiple Choice Questions

Question 1. Energy used in respiration is -
(a) Physical energy
(b) Chemical energy
(c) Kinetic energy
(d) Electric energy
Answer: (b) Chemical energy
In simple words: When living things breathe, they use chemical energy stored in food molecules. This energy is then released to power all body activities.

🎯 Exam Tip: Remember that respiration is a biochemical process that breaks down glucose to release energy, which is a form of chemical energy.

Question 2. During inhalation, the diaphragm is -
(a) Oblique
(b) Dome-shaped
(c) Normal

Question 3. During inspiration occurs -
(a) Contraction of diaphragm and external intercostal muscles.
(b) Relaxation of diaphragm and external intercostal muscles.
(c) Contraction of the only diaphragm.
(d) Relaxation of only external intercostal muscles
Answer: (a) Contraction of diaphragm and external intercostal muscles.
In simple words: When we breathe in, our diaphragm and the muscles between our ribs tighten. This makes our chest bigger so air can rush in.

🎯 Exam Tip: Knowing the muscle actions (contraction/relaxation) for inspiration and expiration is key. Inspiration involves active muscle contraction.

Question 4. During expiration occurs -
(a) Contraction of diaphragm and external intercostal muscles.
(b) Relaxation of diaphragm and external intercostal muscles.
(c) Relaxation of the diaphragm only.
(d) Contraction of diaphragm and external intercostal muscles.
Answer: (b) Relaxation of diaphragm and external intercostal muscles.
In simple words: When we breathe out, our diaphragm and the muscles between our ribs relax. This makes our chest smaller and pushes air out.

🎯 Exam Tip: Expiration during normal breathing is a passive process caused by muscle relaxation and elastic recoil of the lungs.

Question 5. Rate of respiration found in the resting stage of an adult is -
(a) 20 - 22 per minute
(b) 18 – 20 per minute
(c) 16 - 20 per minute
(d) 14 - 16 per minute
Answer: (c) 16 - 20 per minute
In simple words: When an adult is resting, they usually breathe about 16 to 20 times every minute.

🎯 Exam Tip: Memorize the normal ranges for vital signs like respiratory rate, as these are common factual questions.

Question 6. Tidal Volume found in a normal man during resting phase -
(a) 1.2 litre
(b) 2.5 litre
(c) 0.5 litre
(d) 4.5 litre

Question 7. The structural and functional unit of lung is -
(a) Bronchioles
(b) Alveoli
(c) Bronchi
(d) Air sac
Answer: (b) Alveoli
In simple words: The tiny air sacs called alveoli are where oxygen goes into the blood and carbon dioxide leaves. They are the main working parts of the lungs.

🎯 Exam Tip: The alveoli are crucial for gas exchange; always associate them with this primary function.

Question 8. Whizzing sound during expiration is signal of the disease -
(a) Emphysema
(b) Asthma
(c) Bronchitis
(d) Silicosis
Answer: (b) Asthma
In simple words: A wheezing sound when breathing out often means someone has asthma, a condition where the airways get narrow.

🎯 Exam Tip: Recognize common symptoms for respiratory diseases. Wheezing is a classic sign of narrowed airways, often indicating asthma.

Question 9. Labour working in the mines and factories are possible to suffer more from the diseases.
(a) Pneumonia
(b) Bronchitis
(c) Emphysema
(d) Silicosis
Answer: (d) Silicosis
In simple words: Workers in mines and factories are more likely to get silicosis because they breathe in tiny dust particles like silica, which harms their lungs.

🎯 Exam Tip: Connect specific occupations (like mining) with occupational lung diseases caused by dust inhalation, such as silicosis.

Question 10. The total capacity of lungs is -
(a) 4600 ml
(b) 3500 ml
(c) 5800 ml
(d) 2300 ml

Question 1. What is external expiration?
Answer: External expiration is when carbon dioxide (CO2) moves from the lungs out into the surrounding environment. It is also known as breathing out.
In simple words: It's the process of releasing air, especially carbon dioxide, from your lungs into the air outside your body.

🎯 Exam Tip: Clearly distinguish between external (breathing out) and internal respiration (gas exchange at cellular level).

Question 2. What is the respiratory surface?
Answer: The respiratory surface is the area where oxygen (O2) and carbon dioxide (CO2) are exchanged between the body and the environment. For example, the tiny air sacs in our lungs, called alveoli, act as the respiratory surface.
In simple words: It's the special part of your body where oxygen enters the blood and carbon dioxide leaves, like the surface of the lung alveoli.

🎯 Exam Tip: Remember that a respiratory surface needs to be thin, moist, and have a large area for efficient gas exchange.

Question 3. Where diaphragm is found?
Answer: The diaphragm is located between the chest cavity (thoracic region) and the abdominal cavity. It is a large, dome-shaped muscle that helps with breathing.
In simple words: The diaphragm is a muscle found between your chest and belly.

🎯 Exam Tip: Visualize the diaphragm's position as a separator between the chest and abdomen, essential for its role in breathing mechanics.

Question 4. Write the names of inspiratory muscles.
Answer: The main inspiratory muscles are the external intercostal muscles and the diaphragm. Both contract during inspiration.
In simple words: The muscles that help you breathe in are the diaphragm and the external intercostal muscles between your ribs.

🎯 Exam Tip: It is important to know which muscles are responsible for active inspiration (breathing in).

Question 5. Write the names of two diseases caused by smoking?
Answer: Two diseases that can be caused by smoking are Asthma and Emphysema. Smoking damages the airways and lung tissue over time.
In simple words: Smoking can cause lung problems like asthma and emphysema.

🎯 Exam Tip: Always be aware of the serious health risks associated with smoking, especially to the respiratory system.

Question 6. What is expiratory reserve volume?
Answer: Expiratory Reserve Volume (ERV) is the extra amount of air you can forcefully breathe out after a normal breath out. For adults, this volume is typically between 1000 ml to 1100 ml.
In simple words: It is the extra air you can push out of your lungs after you have breathed out normally.

🎯 Exam Tip: Clearly define lung volumes and capacities; distinguish between normal breath and forced (reserve) volumes.

Question 8. What is residual volume?
Answer: Residual volume is the amount of air that always stays in the lungs even after a forceful breath out. This remaining air helps keep the lungs from collapsing and allows continuous gas exchange. It is usually between 1100 ml to 1200 ml.
In simple words: This is the air that always stays in your lungs, even after you try to push out all the air you can.

🎯 Exam Tip: Remember that residual volume cannot be exhaled and is important for maintaining lung structure and function.

Question 9. What is inspiratory capacity?
Answer: Inspiratory capacity is the total amount of air a person can breathe in after a normal breath out. It includes both the tidal volume (normal breath) and the inspiratory reserve volume (extra air that can be inhaled forcefully). For an adult, it is about 3500 ml.
In simple words: It's the total amount of air you can breathe in if you try your hardest after a normal breath out.

🎯 Exam Tip: Inspiratory capacity combines tidal volume and inspiratory reserve volume, representing the maximum inhalation possible.

Question 10. What is a functional residual capacity?
Answer: Functional Residual Capacity (FRC) is the amount of air left in the lungs after a normal, relaxed breath out. This volume is around 2300 ml and includes both residual volume and expiratory reserve volume.
In simple words: It is the air that stays in your lungs after a normal breath out, before you try to breathe in again.

🎯 Exam Tip: Functional residual capacity is an important lung volume that impacts the efficiency of gas exchange at the end of a normal exhalation.

Question 11. What is the significance of artificial respiration?
Answer: Artificial respiration is important for saving the life of someone who has stopped breathing due to accidents, like gas poisoning, electric shock, or carbon monoxide exposure. Mouth-to-mouth breathing is considered the best method for this. It keeps oxygen flowing to the brain and other organs.
In simple words: Artificial respiration is vital to save lives when someone stops breathing, by manually helping them get air. The best way to do this is mouth-to-mouth breathing.

🎯 Exam Tip: Understand that artificial respiration provides immediate support to maintain oxygen supply to the brain and prevent irreversible damage.

RBSE Class 12 Biology Chapter 23 Short Answer Questions

Question 1. Explain the process of inspiration.
Answer: Inspiration, also known as inhalation, is the process of air entering the lungs. It involves a few key steps:
1. Air enters the lungs, which is called inspiration or inhalation.
2. During this process:
• The diaphragm muscles tighten up and move downwards, becoming flatter.
• The external intercostal muscles between the ribs also contract, pulling the ribs and sternum upwards and outwards. This makes the chest cavity bigger, reducing pressure inside the lungs, so air flows in from the outside.
In simple words: Inspiration is when we breathe in. Our diaphragm flattens, and rib muscles pull the chest up and out, making more space for air to enter the lungs.

🎯 Exam Tip: Focus on the muscle contractions and the resulting change in chest cavity volume and pressure that drives air into the lungs.

Question 2. Explain the process of expiration.
Answer: Expiration, or exhalation, is when air leaves the lungs. It also involves several steps:
1. Air leaves the lungs, which is called expiration or exhalation.
2. During this process:
• The diaphragm muscles relax and move upwards, returning to their dome shape.
• The internal intercostal muscles may contract, while external intercostal muscles relax, causing the ribs to move inward and backward. This reduces the size of the chest cavity.
These changes cause the thoracic volume to decrease, and the pressure inside the lungs increases. This higher pressure pushes the air out of the lungs.
In simple words: Expiration is when we breathe out. Our diaphragm and rib muscles relax, making the chest smaller. This pushes air out of the lungs.

🎯 Exam Tip: Remember that normal expiration is a passive process driven by the elastic recoil of the lungs and relaxation of inspiratory muscles, not active contraction (unless forced expiration).

Question 3. Write short notes on:
1. Artificial respiration
2. Respiratory diseases
3. Respiratory volumes
Answer:
1. Artificial Respiration:
This is a method used to help someone breathe when they are not breathing on their own. The main steps are:
• Place the person on a firm surface, lying straight. Support their head to keep the airway open.
• Pinch their nose closed and make an airtight seal with your mouth over theirs.
• Blow air into their mouth about 12 times per minute (each breath about 500 ml).
• Open their nose and mouth to allow the air to come out.
This technique helps to keep oxygen flowing to the body, especially the brain.
2. Respiratory disorders:
These are conditions that affect the lungs and breathing. Some common ones include:
Asthma:
• This is a lung disease where the airways become inflamed, narrow, and swell, producing extra mucus. This makes breathing difficult.
• It is often triggered by pollen, dust, cold, or smoke. Symptoms include coughing, chest pain, and wheezing.
• Avoiding triggers is important. Inhalers can help manage symptoms, and sometimes antibiotics are used for infections.
Bronchitis:
• This disease involves swelling and inflammation of the bronchial tubes, which are the air passages to and from the lungs.
• Symptoms include constant coughing due to swelling in the internal lining of the bronchi.
• It can be acute (sudden and short-lived) or chronic (long-lasting). Exposure to chemicals in tobacco smoke is a common cause, so avoiding smoking can help prevent it.
Emphysema:
• This condition is often caused by heavy smoking and air pollution.
• Smoking continuously damages the tiny air sacs (alveolar walls) in the lungs.
• This damage leads to larger air spaces but reduces the total respiratory surface available for gas exchange in the lungs.
In simple words: Artificial respiration is helping someone breathe manually. Respiratory disorders are diseases like asthma (narrow airways), bronchitis (swollen airways), and emphysema (damaged air sacs), often caused by smoking or pollution.

🎯 Exam Tip: When explaining diseases, define the condition, list common causes, describe symptoms, and mention prevention or treatment methods. For procedures like artificial respiration, clearly list the steps.

3. Respiratory Volumes:
Answer:
1. Tidal Volume (TV): This is the amount of air that a person breathes in or out during a single, normal breath. For humans, this volume is typically around 500 ml.
2. Inspiratory Reserve Volume (IRV): This is the extra amount of air a person can breathe in forcefully after taking a normal breath. It usually ranges from 2500 to 3000 ml.
3. Expiratory Reserve Volume (ERV): This is the extra amount of air a person can forcefully breathe out after a normal exhale. It is typically between 1000 to 1100 ml.
4. Residual Air (RV): This is the volume of air that always remains in the lungs, even after a person has exhaled as much as possible. It is approximately 1100 to 1500 ml in humans.
Functional Residual Capacity (FRC) is the amount of air still in the lungs after a normal expiration. It is formed by combining the Residual Volume (RV) and Expiratory Reserve Volume (ERV), and its total is about 2300 ml in humans.
8. Vital Capacity (VC): This is the largest amount of air a person can breathe out after taking the deepest possible breath. It includes the Inspiratory Reserve Volume (IRV), Tidal Volume (TV), and Expiratory Reserve Volume (ERV). In humans, vital capacity is about 4600 ml.
9. Total Lung Capacity (TLC): This represents the maximum amount of air that the lungs can hold after a very deep breath. It is calculated by adding the Vital Capacity (VC) and the Residual Volume (RV). For humans, the total lung capacity is approximately 5800 ml.
In simple words: These terms describe different amounts of air in our lungs: how much we breathe normally, how much extra we can force in or out, and the air that always stays inside.

🎯 Exam Tip: Remember the full form and approximate values for each respiratory volume and capacity, as they are key concepts in understanding lung function.