Breathing and Exchange of Gases - NEET Important Questions

The Class 11 chapter ‘Breathing and Exchange of Gases’ covers concepts like the anatomy of the respiratory system and all processes associated with breathing. Here, let’s have a glance at some important MCQs from this chapter for the upcoming NEET exam.

1. Which one of the following statements is not correct

1. Cellular respiration is the process of the exchange of gases between the lungs and the atmosphere
2. Breathing is an extracellular process
3. Energy is used in the process of breathing
4. Several enzymes are involved in the process of respiration

Answer: a. Cellular respiration is the process of the exchange of gases between the lungs and the atmosphere

Discussion:

2. Arrange the following parts of the human respiratory tract in the same order in which air flows during expiration:

Nasal chamber, pharynx, larynx, internal nares, trachea, lungs

1. Nasal chamber ▻ internal nares ▻ pharynx ▻ larynx ▻ trachea ▻ lungs
2. Nasal chamber ▻ pharynx ▻ internal nares ▻ larynx ▻ trachea ▻ lungs
3. Lungs ▻ trachea ▻ larynx ▻ internal nares ▻ pharynx ▻ nasal chamber
4. Lungs ▻ trachea ▻ larynx ▻ pharynx ▻ internal nares ▻ nasal chamber

Answer: d. Lungs ▻ trachea ▻ larynx ▻ pharynx ▻ internal nares ▻ nasal chamber

Discussion: Expiration or exhalation is the movement of air expelled from the lungs into the airways and then to the external environment via breathing. The sequence of airflow is as follows:

Lungs ▻ trachea ▻ larynx ▻ pharynx ▻ internal nares ▻ nasal chamber

3. Assertion: The food can’t enter the larynx during swallowing.

Reason: The glottis is closed by the epiglottis during the swallowing of food.

1. Both the assertion and reason are true and the reason is the correct explanation for the assertion.
2. Both the assertion and reason are true but the reason is not the correct explanation for the assertion.
3. Assertion is true but the reason is false
4. Reason is true but the assertion is false

Answer: a. Both the assertion and reason are true and the reason is the correct explanation for the assertion.

Discussion: Epiglottis covers the glottis during the swallowing of food to prevent the entry of food into the respiratory tract and further into the larynx, trachea and lungs.

4. Which of the following is present in the human trachea?

1. Ventrally incomplete C-shaped rings of hyaline cartilage
2. Dorsally incomplete C-shaped rings of elastic cartilage
3. Dorsally incomplete C-shaped rings of hyaline cartilage
4. Ventrally incomplete C-shaped rings of elastic cartilage

Answer: c. Dorsally incomplete C-shaped rings of hyaline cartilage

Discussion: The outermost layer of the trachea is tunica adventitia which is made up of white fibrous connective tissue. The trachea contains 16 to 20 C-shaped rings of hyaline cartilage which are incomplete at the dorsal surface. These C-shaped cartilages prevent the trachea from collapsing and also provide flexibility.

5. What is the primary site for respiratory gas exchange in the human body?

1. Alveoli
2. RBC
3. Nose
4. Trachea

Answer: a. Alveoli

Discussion: Alveoli are thin, irregular and vascularised bag-like structures that arise from the terminal bronchioles within the lungs. These are the primary sites of gas exchange between blood capillaries and the lungs.

Alveoli are lined by numerous blood vessels. As the alveoli and blood vessels are in close proximity, diffusion of gases takes place between the alveoli and blood vessels.

6. Which of the following metal elements plays an important role in the transport of respiratory gases?

1. Zinc
2. Potassium
3. Iron
4. Calcium

Answer: c. Iron

Discussion: RBC or the red blood cell contains haemoglobin, an iron-containing pigment. Each haemoglobin has 4 globins and 4 heme groups. Each heme group contains iron pigments in it. Iron helps in the binding of gases with RBC.

7. Select the correct statements

1. Thoracic chamber is located lower to the abdomen
2. Thoracic chamber is built by dorsal ribs, ventral vertebral column, lower diaphragm and a lateral sternum
3. Increase in the thoracic volume causes a similar increase in pulmonary volume
4. Humans can increase the strength of inspiration and expiration with the help of additional muscles in the abdomen
5. Only 1 is correct
6. Both 2 and 3 are correct
7. Both 3 and 4 are correct
8. All are correct

Answer: c. Both 3 and 4 are correct

Discussion: The thoracic chamber is located in the upper part of the body. It is built by –

• Vertebral column (backbone) dorsally
• Sternum (breastbone) ventrally
• Ribs laterally
• Thin muscular dome-shaped diaphragm

An increase in the thoracic volume causes a similar increase in pulmonary volume. Also, humans can increase the strength of inspiration and expiration with the help of additional muscles in the abdomen.

8. The structure that encloses the thoracic cavity of mammals at the bottom is made up of

1. Longitudinal muscle
2. Circular muscle
3. Elastic cartilage
4. Radial muscle

Answer: d. Radial muscle

Discussion: Diaphragm is a dome-shaped structure which encloses the thoracic cavity at the bottom. It is a muscular septum which divides the body cavity into the upper thoracic cavity and lower abdominal cavity. This diaphragm is made up of radial muscles which originate from the peripheral muscle and is inserted in the central region of the diaphragm. By the contraction of these muscles, the diaphragm flattens and the volume of the thoracic cavity increases, which helps in inspiration.

9. Inspiration occurs when the pressure within the lungs is

1. Less than the atmospheric pressure
2. Greater than the atmospheric pressure
3. Equal to the atmospheric pressure
4. Both A and C

Answer: a. Less than the atmospheric pressure

Discussion: Inspiration is the ‘breathing in’ process in which the lungs expand to fill the increased space in the thoracic cavity. Here, the intrapulmonary pressure decreases and air rushes in.

Also Check:Difference between Inhalation and Exhalation

10. During inspiration, the external intercostal muscles ⸻ and the ribs move ⸻

1. Relax upwards and outwards
2. Contracts upwards and outwards
3. Relax downwards and inwards
4. Contract downwards and inwards

Answer: b. Contracts upwards and outwards

Discussion: During inspiration, the external intercostal muscles contract and the ribs move upwards and outwards. During expiration, the external intercostal muscles relax and the ribs move downwards and inwards.

11. The volume of air taken in and out of the lungs during normal breathing is called ⸻

1. Tidal volume
2. Residual volume
3. Inspiratory reserve volume
4. Expiratory reserve volume

Answer: a. Tidal volume

Discussion:

12. The maximum volume of air that can be breathed in after normal expiration is called ⸻

1. Inspiratory capacity
2. Expiratory capacity
3. Vital capacity
4. Total lung capacity

Answer: a. Inspiratory capacity

Discussion: Inspiratory capacity is the maximum volume of air that can be breathed in after normal expiration. IC = TV + IRV.

13. Volume of air that will remain in the lungs after a normal expiration, which includes ERV + RV is called ⸻

1. Inspiratory capacity
2. Expiratory capacity
3. Functional residual capacity
4. Total lung capacity

Answer: c. Functional residual capacity

Discussion: Functional residual capacity (FRC) is the volume of air that remains in the lungs after normal expiration. FRC = ERV + RV.

14. Which of the following statements regarding gaseous transportation is not correct?

1. Oxygen irreversibly binds to haemoglobin
2. Carbon dioxide reversibly binds to haemoglobin
3. Oxygen is transported by RBCs and plasma
4. All are correct

Answer: a. Oxygen irreversibly binds to haemoglobin

Discussion: Oxygen is transported by RBCs and plasma. The oxygen usually binds with haemoglobin present in the red blood cells (RBCs) in a reversible manner and forms a compound called oxyhaemoglobin.

In alveoli = Haemoglobin + Oxygen → Oxyhaemoglobin

In tissue = Oxyhaemoglobin → Haemoglobin + Oxygen

Carbon dioxide binds with haemoglobin present in the red blood cells (RBCs) in a reversible manner to form carbamino haemoglobin.

In tissue = Haemoglobin + Carbon dioxide → Carbamino haemoglobin

In alveoli = Carbamino haemoglobin → Haemoglobin + Carbon dioxide

15. What is/are the factor(s) that affect the transportation of oxygen within the body?

1. Partial pressure of oxygen and carbon dioxide
2. Temperature
3. Hydrogen ion concentration
4. All the above

Answer: d. All the above

Discussion: Factors that affect the transportation of oxygen within the body are as follows

16. Approximately 70% of CO₂ in the blood is transported as ⸻

1. Bicarbonate ions
2. Carbamino haemoglobin
3. Gaseous form
4. Carbon monoxide

Answer: a. Bicarbonate ions

Discussion: Carbon dioxide can be transported as –

• Carbamino haemoglobin – carbon dioxide bound to haemoglobin in red blood cells (RBCs).
• Dissolved form – carbon dioxide is dissolved in blood plasma.
• Bicarbonates – carried as bicarbonates.

17. Increase in CO₂ causes the release of O₂ from haemoglobin into tissues. This is known as

1. Cooling effect
2. Haldane effect
3. Bohr effect
4. Hall effect

Answer: c. Bohr effect

Discussion:

• Bohr effect – increase in CO₂ causes release of O₂ from Hb into tissues.
• Haldane effect – increase in O₂ causes release of CO₂ from Hb in the lungs.

18. Which region in the brain helps regulate respiration?

1. Pons
2. Medulla
3. Cerebellum
4. Both A and B

Answer: d. Both A and B

Discussion: Both medulla and pons have regions responsible for the regulation of respiration. The medulla contains a respiratory rhythm centre that primarily controls the respiratory rhythm. Pons possess a pneumotaxic centre that moderates the function of the respiratory rhythm centre.

19. Which of the following helps prevent the lungs from over-expanding during inspiration?

1. Medullary centre
2. Pneumotaxic centre
3. Apneustic centre
4. Dorsal respiratory group

Answer: b. Pneumotaxic centre

Discussion: The Pneumotaxic centre is located in the superior part of the pons (part of the hindbrain). It helps to moderate the functions of the respiratory rhythm centre present in the medulla. It gives inhibitory signals for inspiration which prevents over-expansion of the lungs. The medullary centre is also called the respiratory rhythm centre and it is primarily responsible for the regulation of the rate of breathing. The apneustic centre located in the lower part of the pons helps in moderating the functions of the respiratory rhythm centre present in the medulla.

See more:Functions of Pons

20. A patient’s diagnostic test revealed that his alveolar walls are damaged. This led to a plunge in the respiratory area. This patient also has a history of intense cigarette smoking. Which respiratory disorder can this patient be suffering from?

1. TB
2. Pneumonia
3. Emphysema
4. Sneezing

Answer: c. Emphysema

Discussion: The patient is suffering from emphysema.

Causes – smoking and toxic substances.

Symptoms – walls of alveoli are damaged and breathing becomes difficult.

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