MCQ Biology Chapter 14: BREATHING AND EXCHANGE OF GASES, HS 1st year

 

Breathing and Exchange of Gases

1. Which of the following structures prevents food from entering the trachea during swallowing?
   a) Larynx
   b) Glottis
   c) Epiglottis
   d) Alveoli

   • Answer: c) Epiglottis

2. What is the primary site of gas exchange in humans?
   a) Bronchi
   b) Alveoli
   c) Trachea
   d) Pharynx

   • Answer: b) Alveoli

3. Which respiratory volume refers to the additional air that can be forcibly inhaled after a normal inspiration?
   a) Residual Volume (RV)
   b) Expiratory Reserve Volume (ERV)
   c) Tidal Volume (TV)
   d) Inspiratory Reserve Volume (IRV)

   • Answer: d) Inspiratory Reserve Volume (IRV)

4. What is the total lung capacity (TLC) composed of?
   a) RV, ERV, TV, IRV
   b) TV, ERV, RV
   c) RV, TV, IRV
   d) IRV, ERV, VC

   • Answer: a) RV, ERV, TV, IRV

5. Which of the following is a disorder caused by the damage to alveolar walls due to smoking?
   a) Asthma
   b) Emphysema
   c) Fibrosis
   d) Hypoxia

   • Answer: b) Emphysema

Transport of Gases

6. What percentage of oxygen is transported by binding to hemoglobin in the blood?
   a) 50%
   b) 70%
   c) 97%
   d) 3%

   • Answer: c) 97%

7. What is the primary enzyme that helps convert carbon dioxide into bicarbonate ions in the blood?
   a) Carbonic anhydrase
   b) Hemoglobinase
   c) Amylase
   d) Lipase

   • Answer: a) Carbonic anhydrase

8. In tissues, what happens to hemoglobin in the presence of high pCO₂ and low pO₂?
   a) Binds oxygen tightly
   b) Releases oxygen
   c) Becomes saturated with oxygen
   d) Converts into carbonic anhydrase

   • Answer: b) Releases oxygen

Regulation and Disorders of Respiration

9. Which brain region primarily regulates the respiratory rhythm?
   a) Pons
   b) Medulla
   c) Cerebellum
   d) Thalamus

   • Answer: b) Medulla

10. What is the cause of hypoxia?
    a) Excessive oxygen levels in blood
    b) Reduced oxygen availability to tissues
    c) High levels of carbon dioxide in tissues
    d) Rapid breathing rate

• Answer: b) Reduced oxygen availability to tissues

11. Which of the following organisms uses cutaneous respiration?
    a) Fish
    b) Frog
    c) Insects
    d) Birds

    • Answer: b) Frog

12. What is the average number of breaths per minute in a healthy human at rest?
    a) 10-12
    b) 12-16
    c) 20-24
    d) 18-20

    • Answer: b) 12-16

13. Which muscle contraction increases the thoracic volume during inspiration?
    a) Diaphragm and internal intercostal muscles
    b) External intercostal muscles and diaphragm
    c) Sternum and abdominal muscles
    d) Internal intercostal muscles and abdominal muscles

    • Answer: b) External intercostal muscles and diaphragm

14. What is the function of pleural fluid in the lungs?
    a) Facilitates gas exchange
    b) Reduces friction on lung surfaces
    c) Increases pulmonary volume
    d) Absorbs carbon dioxide

    • Answer: b) Reduces friction on lung surfaces

15. The part of the respiratory system from nostrils to terminal bronchioles is called the:
    a) Conducting part
    b) Exchange part
    c) Respiratory membrane
    d) Pulmonary cavity

    • Answer: a) Conducting part

Respiratory Volumes and Capacities

16. What is the approximate residual volume (RV) of air left in the lungs after maximal expiration?
    a) 2500 mL
    b) 1000 mL
    c) 500 mL
    d) 1100-1200 mL

    • Answer: d) 1100-1200 mL

17. Which capacity refers to the maximum volume of air that can be inspired after a normal expiration?
    a) Total Lung Capacity (TLC)
    b) Inspiratory Capacity (IC)
    c) Vital Capacity (VC)
    d) Functional Residual Capacity (FRC)

    • Answer: b) Inspiratory Capacity (IC)

18. What is the approximate tidal volume for a healthy human?
    a) 1000 mL
    b) 500 mL
    c) 3000 mL
    d) 1100 mL

    • Answer: b) 500 mL

Gas Exchange and Transport

19. Where does the diffusion of oxygen and carbon dioxide occur?
    a) Bronchioles
    b) Trachea
    c) Alveoli
    d) Larynx

    • Answer: c) Alveoli

20. What makes carbon dioxide diffusion faster than oxygen in the body?
    a) Lower solubility of carbon dioxide
    b) Higher partial pressure of oxygen
    c) Higher solubility of carbon dioxide
    d) Smaller molecular size of carbon dioxide

    • Answer: c) Higher solubility of carbon dioxide

Respiratory Disorders

21. Which respiratory disorder is caused by prolonged exposure to dust in certain industries?
    a) Asthma
    b) Fibrosis
    c) Emphysema
    d) Pneumonia

    • Answer: b) Fibrosis

22. What is the main characteristic of asthma?
    a) Damaged alveolar walls
    b) Difficulty in breathing with wheezing
    c) Fibrosis of lung tissues
    d) Excessive oxygen absorption

    • Answer: b) Difficulty in breathing with wheezing

23. What is the primary cause of emphysema?
    a) Bacterial infection
    b) Cigarette smoking
    c) Viral infection
    d) Genetic mutation

    • Answer: b) Cigarette smoking

24. Which condition can occur at high altitudes due to reduced oxygen availability?
    a) Hypercapnia
    b) Hypoxia
    c) Pneumonia
    d) Acidosis

    • Answer: b) Hypoxia

25. What is a common protective measure for workers in industries producing excessive dust?
    a) Regular spirometer tests
    b) Wearing protective masks
    c) Increased physical exercise
    d) Vitamin supplements

    • Answer: b) Wearing protective masks