Respiratory System

In humans, taking air through nostrils into the nasal cavity is called

1. Inhalation
2. Exhalation
3. Cellular respiration
4. Internal respiration

Answer

Inhalation

Reason — Inhalation is the physical process by which the air containing oxygen is drawn into our lungs through nostrils into the nasal cavity.
Exhalation is releasing air out of the body. Cellular respiration is breakdown of food in cells. Internal respiration is gas exchange between blood and tissues.

The front opening of the wind pipe is guarded by

1. Glottis
2. Exoglottis
3. Epiglottis
4. Trachea

Answer

Epiglottis

Reason — The epiglottis is a muscular flap located in the throat. It closes the wind pipe at the time of swallowing of food.
Glottis is opening of the larynx, not a guard. Exoglottis is not a biological structure. Trachea is the windpipe itself.

The process during which food is oxidised and energy is released is called

1. Cellular respiration
2. Excretion
3. Digestion
4. Transpiration

Answer

Cellular respiration

Reason — Cellular respiration is the process of oxidation of glucose (breaking down of food) in the cells with the release of energy in the form of ATP molecules (Adenosine triphosphate).
Excretion is removal of waste products. Digestion is breakdown of food into simpler substances. Transpiration is loss of water vapour from plants

Which of the following is not a part of the respiratory system ?

1. Nostrils
2. Lungs
3. Mouth
4. Trachea

Answer

Mouth

Reason — In humans, the organs of the respiratory system are the nose, pharynx, larynx, trachea, bronchi and lungs. The mouth belongs to the digestive system and is not a respiratory organ — air should normally enter through the nose, not the mouth.

The common passage of wind pipe and food pipe is termed as :

1. Larynx
2. Glottis
3. Pharynx
4. Epiglottis

Answer

Pharynx

Reason — Pharynx or throat is a common passage for air and the food. It leads into two passages, one is the air tube called wind pipe or trachea and the other the gullet (food-pipe).
Larynx is voice box, only air passage. Glottis is the opening of the larynx. Epiglottis is the flap that prevents food entering windpipe.

The energy produced during cellular respiration is :

1. ADP
2. ADH
3. ATP
4. None of the above

Answer

ATP

Reason — During cellular respiration, glucose is oxidised in the cells and the energy released is stored in the form of adenosine triphosphate (ATP), along with carbon dioxide and water vapour. ADP (adenosine diphosphate) is the lower-energy molecule that is converted into ATP when energy is stored, so it is not the energy product. ADH (antidiuretic hormone) is a hormone that controls water balance in the body and has nothing to do with respiration.

The basic structural and functional unit of the lungs is :

1. Pleura
2. Alveolus
3. Capillary
4. Diaphragm

Answer

Alveolus

Reason — Alveolus is the basic structural and functional unit of the lungs.
Pleura is the membrane covering lungs. Capillary is the blood vessel, not lung unit. Diaphragm is the muscle for breathing.

Vocal cords are found in :

1. Larynx
2. Gullet
3. Pharynx
4. Glottis

Answer

Larynx

Reason — Larynx contains two ligamentous folds called 'vocal cords'.
Gullet is the food pipe (esophagus). Pharynx is the common passage for air and food. Glottis is the opening between vocal cords, not their location.

Which of the following is a respiratory pigment ?

1. Melanin
2. Haemoglobin
3. Chlorophyll
4. None of the above

Answer

Haemoglobin

Reason — The oxygen from the lungs diffuses into the blood, and is picked up by haemoglobin in red blood cells. Carbon dioxide from the blood diffuses into the lungs and is exhaled out through the same passage.
Melanin is the skin pigment, gives color. Chlorophyll is the photosynthetic pigment in plants.

The muscular sheet which divides the body cavity into thorax and abdomen is termed as :

1. Inner pleura
2. Rib cage
3. Outer pleura
4. Diaphragm

Answer

Diaphragm

Reason — Diaphragm is a muscular sheet which internally divides the body cavity into two cavities, the chest cavity or thoracic cavity above, and the abdominal cavity below.
Inner pleura is the membrane covering lungs. Rib cage is the bony structure protecting chest. Outer pleura is the membrane around lungs.

Assertion: The energy produced during the process of respiration is utilized by the body for various external and internal activities.

Reason: No energy is used by the body during sleep because all physical activities stop when we are asleep.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

A is true but R is false.

Reason — A is true as respiration releases energy in cells, and this energy is used for movement, growth, repair and internal functions.
R is false as even during sleep, the body uses energy for internal processes like breathing, heartbeat.

Therefore, A is true but R is false is the correct option.

Assertion: The front opening (glottis) of the wind pipe is guarded by a muscular flap called epiglottis which prevents the entry of food in the trachea.

Reason: The trachea is supported by C-shaped cartilage rings that keep it open for the passage of air.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true but R is not the correct explanation of A.

Reason — A is true as the front opening (glottis) of the wind pipe is guarded by a muscular flap called epiglottis which prevents the entry of food in the trachea.
R is true as the trachea has C-shaped cartilage rings that prevent it from collapsing and keep the airway open. However, this describes a separate feature of the trachea and does not explain how the epiglottis prevents food from entering the windpipe.

Therefore, Both A and R are true but R is not the correct explanation of A is the correct option.

Assertion: Alveoli are the basic structural and functional units of lungs which are richly supplied with blood capillaries.

Reason: The thin walls of the blood capillaries allow faster diffusion of the respiratory gases into the lungs as alveoli are surrounded by blood capillaries.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true and R is the correct explanation of A.

Reason — A is true as alveoli are the functional units of lungs which are richly supplied with blood capillaries covering their walls.
R is true as the walls of the blood capillaries are extremely thin and moist for allowing faster diffusion of gases.

Therefore, Both A and R are true and R is the correct explanation of A is the correct option.

Assertion: Air enters the lungs during inhalation because the pressure inside the lungs becomes lower than the air outside.

Reason: The chest cavity becomes smaller during inhalation, which forces air to rush in.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

A is true but R is false.

Reason — A is true as during inhalation, lung volume increases and internal pressure decreases, so air flows from higher external pressure to lower internal pressure.
R is false as during inhalation, the chest cavity actually expands (becomes larger), not smaller. This expansion reduces pressure inside the lungs and draws air in.

Therefore, A is true but R is false is the correct option.

Assertion: In an alveolus, carbon dioxide diffuses from the air into the blood.

Reason: Carbon dioxide concentration is higher in the blood than in the alveolar air.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

A is false but R is true.

Reason — A is false as carbon dioxide diffuses from the blood into the alveolar air.
R is true because blood coming from body tissues carries more CO₂ than the air in alveoli, so CO₂ moves from blood to alveoli by diffusion.

Therefore, A is false but R is true is the correct option.

Fill in the blanks with suitable words :

(i) The ............... emerges from the larynx down below in the neck.
(ii) The inner lining of trachea consists of ............... epithelium.
(iii) ............... end up into microscopic alveoli.
(iv) The volume of chest cavity ............... during inspiration.
(v) The amount of ............... gas remains the same in the inspired air and expired air.

Answer

(i) trachea
(ii) ciliated
(iii) Bronchioles
(iv) increases
(v) Nitrogen

Match the terms given in column A with those of column B

Answer

Why do our body cells require oxygen?

Answer

Our body cells require oxygen for the break down of glucose and release energy for carrying out various activities of the body.

What is the difference between breathing and respiration?

Answer

Difference between Breathing and Respiration:

Name the by-products formed during the oxidation of food.

Answer

Carbon dioxide and Water are released as by-products during the oxidation of food.

Name the agent which transports oxygen to all parts of the body.

Answer

Blood with help of haemoglobin in RBCs transports oxygen to all parts of the body.

What is the role of epiglottis during swallowing?

Answer

Epiglottis closes the wind pipe at the time of swallowing the food.

Name the gas which is expelled out during expiration. Where is it originally produced in our body?

Answer

Carbon dioxide is the gas which is expelled during expiration. It is produced in the cells of the body.

Write one important role of each of the following .

(i) Epiglottis
(ii) Larynx
(iii) Alveolus
(iv) Pleura
(v) Nasal chamber

Answer

(i) Epiglottis guards the front opening (glottis) of the wind pipe. It closes the wind pipe at the time of swallowing of food, and hence prevents any wrongful entry of food into the wind pipe.

(ii) Larynx contains two ligamentous folds called 'vocal cords'. Air expelled forcibly through the vocal cords vibrates them to produce sound.

(iii) Alveoli are richly supplied with blood capillaries covering their walls. The walls of the alveoli are extremely thin and moist for allowing faster diffusion of gases.

(iv) Pleura protects the lungs. The fluid filled in the space between the outer and inner pleura acts as a shock absorber for the lungs.

(v) The lining of the nasal chamber has mucous (a sticky fluid) which traps germs and dust, so they don't enter our body.

Define the terms given below :

(i) Respiration
(ii) Breathing
(iii) Lungs
(iv) Inhalation
(v) Exhalation

Answer

(i) Respiration — Respiration is the process of releasing energy by breaking down food (glucose) needed for various activities of the body.

(ii) Breathing — The process during which the air containing oxygen is drawn into the lungs and the air containing carbon dioxide is forced out from the lungs is called breathing. Breathing is a physical process.

(iii) Lungs — The lungs are a pair of pink and spongy, elastic organs located in the chest cavity and help in the exchange of gases. They take in oxygen from the air and remove carbon dioxide from the blood during the process of breathing.

(iv) Inhalation — Inhalation is the process of drawing in the air through the nostrils into the nasal cavity and finally into the lungs.

(v) Exhalation — Exhalation is the process of forcing out of the air from the lungs.

Name the following.

(i) Respiratory process in which oxygen is not utilized.
(ii) Respiratory process in which oxygen is utilized.
(iii) The microscopic air-sacs of the lungs.
(iv) The two membranes which protect the lungs.
(v) Six main parts of the human respiratory system.
(vi) Two types of respiration.
(vii) Three phases of respiration.
(viii) Two steps of breathing.
(ix) Three common respiratory diseases.

Answer

(i) Anaerobic Respiration.
(ii) Aerobic Respiration.
(iii) Alveoli.
(iv) Outer and inner pleura.
(v) Nose, Pharynx, Larynx, Trachea, Bronchi and the Lungs
(vi) Aerobic respiration and Anaerobic respiration
(vii) Breathing, Gaseous transport, and Cellular respiration
(viii) Inspiration and Expiration
(ix) Bronchitis, Asthma, and Pneumonia

Correct the following statements by changing the first/ last word only :

(i) BCG is a kind of vaccine used to prevent Pneumonia.
(ii) Streptomycin is a kind of vaccine.
(iii) Breathing is a bio-chemical process.
(iv) The amount of oxygen in expired air is 21%.
(v) The front opening of the trachea is guarded by a muscular flap called diaphragm.

Answer

(i) BCG is a kind of vaccine used to prevent Tuberculosis.
(ii) Streptomycin is a kind of antibiotic.
(iii) Respiration is a bio-chemical process.
(iv) The amount of oxygen in expired air is 16%.
(v) The front opening of the trachea is guarded by a muscular flap called epiglottis.

Why is a respiratory system necessary?

Answer

Respiratory system is necessary because:

1. Respiration is a vital process in all living organisms. Every cell of a plant, an animal or of human body requires energy for various activities. Respiratory system provides this energy by the oxidation of glucose using oxygen.
2. Respiratory system helps in breathing through which oxygen from the air is pulled into the lungs and the air containing carbon dioxide is forced out of the lungs.
3. Respiratory system helps in gaseous transport. Oxygen of the inhaled air is absorbed by the blood in the lungs where it combines with the haemoglobin present in RBCs. The Oxygen is carried from lungs to the body tissues where the Oxygen is utilised and Carbon dioxide is released.

What factors are most likely to affect the breathing rate?

Answer

Some of the factors that affect the breathing rate are:

1. While exercising or doing intense physical activity, the body requires more energy due to which the demand of oxygen increases. This increases the rate of breathing of the person.
2. While sleeping and resting, the breathing rate decreases as the body requires less energy.
3. Allergic reactions increase the rate of breathing as allergic reactions narrow the nasal passage leading to a demand for more oxygen.
4. Stress and anxiety increases the breathing rate as the stress hormones trigger the body's fight or flight response.

What happens to the energy liberated during respiration?

Answer

The energy liberated during respiration is not all in the form of heat but a large part of it is converted into chemical energy in the form of ATP (Adenosine Triphosphate). This energy is utilised by the body cells for a vast variety of activities like:

1. Digestion of food.
2. Production of enzymes.
3. Contraction of muscles for movement.
4. Conduction of electrical impulse in a nerve cell.
5. Production of new cells by cell division.
6. Keeping the body warm in warm-blooded animals.

What do you understand by inhalation and exhalation? How are they different from each other?

Answer

Inhalation is the physical process by which the air containing oxygen is drawn into the lungs.

Exhalation is the physical process by which the air containing carbon dioxide is forced out from the lungs.

Differences between Inhalation and Exhalation are:

What do you understand by the term respiratory diseases? Name any three common respiratory diseases.

Answer

The diseases that affect the respiratory organs of the body making respiration difficult are termed as respiratory diseases.

The three common respiratory diseases are:

1. Bronchitis
2. Asthma
3. Pneumonia

State the cause and treatment for the following diseases:

(i) Tuberculosis
(ii) Pneumonia
(iii) Bronchitis

Answer

(i) Tuberculosis
Cause — This respiratory infection is caused by bacteria that can spread by air, dust or sputum.
Treatment — BCG vaccine, antibiotic Streptomycin.

(ii) Pneumonia
Cause — This respiratory disease is mainly caused by bacteria inhaled through air or by contact.
Treatment — Antibiotic - Penicillin.

(iii) Bronchitis
Cause — This respiratory infection is mainly caused by a virus. Air pollution and smoking can also cause bronchitis.
Treatment — Drinking plenty of fluids, following a well balanced diet, frequent hand washing and adequate rest can prevent and improve bronchitis.

Describe in brief the function of ribs and diaphragm in breathing.

Answer

The function of Ribs and Diaphragm is to aid respiration:

1. Ribs — In breathing during inhalation, the Ribs move upwards and outward. This function increases the volume of chest cavity. As a result lungs expand and atmospheric air rushes into the lungs. During Exhalation, the Ribs move downwards and inward. This function decreases the volume of chest cavity as a result lungs contract and air rushes out of the lungs.
2. Diaphragm — The diaphragm helps in breathing by changing its shape. During inhalation, it contracts and flattens, allowing the lungs to expand. During exhalation, it relaxes and becomes dome-shaped, helping push air out of the lungs.

The diagram given alongside is an experimental set up mimicking a certain process occurring in living beings. Study the figure and answer the following questions :

(i) Name the process and define it.

(ii) What are the two phases of the above mentioned process shown as (A) and (B) ?

(iii) Name the particular organs of the body shown in the figure with :
(a) Bell jar (b) Balloons (c) Rubber sheet

(iv) How do these phases (A) and (B) differ with respect to the position of ribs ?

(v) Does the breathing rate of a young boy and an old person differ ? Explain.

Answer

(i) The given diagram shows an experimental set up to demonstrate the process of Breathing.

Breathing is the process during which the air containing oxygen is drawn into the lungs and the air containing carbon dioxide is forced out from the lungs. It is a physical process.

(ii) Phase (A) shows Inspiration, and Phase (B) shows Expiration.

(iii) The particular organs of the body shown in the figure are:
     (a) Bell jar — Chest cavity
     (b) Balloons — Lungs
     (c) Rubber sheet — Diaphragm

(iv) During Inspiration [Phase (A)], ribs move upwards and outwards while during Expiration [Phase (B)] ribs move downwards and inwards.

(v) Yes, the breathing rate of a young boy and an old person typically differs. Young children have a higher breathing rate than adults, due to their higher metabolic needs and smaller lung capacity relative to their body size. In contrast, older people breathe more slowly as their metabolic rate is lower and lung function may decline with age.

The diagram given alongside shows the "Human Respiratory System". Study the same and answer the following questions :

(i) Label the guidelines 1 to 4.

(ii) Define the structure shown as part 2.

(iii) Name the basic structural and functional unit of part 3.

(iv) Write one specific structural feature of the inner lining of part 1.

(v) What is the muscular sheet on which part 3 rests ?

Answer

(i) The guidelines 1 to 4 show:

1. Trachea
2. Larynx
3. Lung
4. Bronchus

(ii) At the entrance of the trachea, there is a voice box called larynx. It contains two ligamentous folds called 'vocal cords'. Air expelled forcibly through the vocal cords vibrates them, to produce sound.

(iii) Alveoli is the basic structural and functional unit of part 3, i.e., lungs.

(iv) The inner linings of the trachea, bronchi and bronchioles have ciliated epithelium. The continuous movement of the cilia pushes out the unwanted particles that may be present in the inhaled air.

(v) Diaphragm is the muscular sheet upon which the lungs rest.

Vivaan is a class 6 boy who loves playing football and shouting instructions to his teammates on the field. One afternoon, during an intense match, he starts feeling like something is stuck in his throat. He keeps clearing it, but it doesn't help. By the end of the game, his voice becomes weak and hoarse, and speaking starts to hurt. Answer the following questions:

(i) Write the technical term for the voice-box found in the human body that was affected in Vivaan's case.

(ii) What is the exact location of the voice-box in our body?

(iii) What could be the possible reason for Vivaan temporarily losing his voice?

(iv) Name the two ligamentous folds associated with the voice-box.

Answer

(i) The technical term for the voice-box found in the human body is the larynx.

(ii) Larynx is located at the entrance of the trachea.

(iii) Vivaan’s temporary loss of voice could be due to overuse or strain of the vocal cords caused by shouting continuously during the football match.

(iv) The two ligamentous folds associated with the voice-box are called vocal cords.