CBSE Questions for Class 11 Medical Biology Breathing And Exchange Of Gases Quiz 13 - MCQExams.com

• During exhalation, the diaphragm relaxes and moves upward becoming dome-shaped. 
• Intercostal muscles present between the ribs relax and space in the thoracic cavity decreases. 
• Due to reduced space, air pressure in the thoracic cavity increases and the air is forced out. 

$$\textbf{Correct Option D}$$

$$\textbf{Solution}$$

$$\bullet$$ Cyanosis is the change in the color of the body tissues from normal to bluish purple color.

• When a person is on a high altitude, he has to acclimatize to it. 
• Breathing becomes difficult at high altitudes, because of the low density of the air. There is not sufficient oxygen in the atmosphere to oxygenate the blood adequately. 
• The oxygenation of blood depends upon the partial pressure of oxygen in the atmosphere. As atmospheric pressure decreases, so do the partial pressure of the oxygen. 
• For short durations, humans compensate for high altitudes by increasing the respiratory rate (hyperventilation). During a longer period of acclimatization, physiological changes occur. 
• The number of red blood cells in the blood increases (polycythemia). Other changes in the body's acid-base balance can also happen.

$$\textbf{Correct option:A}$$ 

$$\textbf{A-2:}$$

$$\bullet$$ Residual volume is the amount of air which remains still long after the maximum forced expiration; it is about 1100 mL to 1200 mL.

$$\textbf{B-1:}$$

$$\bullet$$ Vital capacity is defined as the maximum amount of air a person can breathe in after a compelled expiration or the maximum amount of air a person can breathe out after a forced inspiration. Vital capacity includes tidal volume, inspiratory reserve volume and expiratory reserve volume which gives the total vital capacity of around 3.4 L to 4.8 L.

$$\textbf{C-4:}$$

$$\bullet$$ Inspiratory reserve volume is the excessive amount of air that can be inspired forcefully after a normal inspiration ,thus it is forced inspiration which is about 2.5 mL to 3.5 mL of air.

$$\textbf{D-3:}$$

$$\bullet$$ Inspiratory capacity is the total volume of air a person can inspire after a normal expiration ,it is equivalent to sum of tidal volume and inspiratory reserved volume of air that can be about 3L to 4 L .

$$\textbf{Hence, the correct option is (A)}$$

• Chronic obstructive pulmonary disease (COPD), also known as chronic obstructive lung disease (COLD), is a type of obstructive lung disease characterized by chronically poor airflow. It worsens over time. 
• The main symptoms include shortness of breath, cough, and sputum production. 
• It is divided into emphysema and chronic bronchitis. 
• COPD is almost always caused by smoking.
• Over time, breathing tobacco smoke irritates the airways and destroys the stretchy fibres in the lungs.

$$\textbf{Correct option:A}$$ 

$$\textbf{Solution:}$$

$$\bullet$$ During embryonic development,the anomalous lateral course of azygos vein in the pleural septum within the upper lobe originates into azygos lobe , thus it is a congenital variation of the right upper lobe of lungs. 

$$\bullet$$ Azygos lobe does not have any bronchioles,veins and arteries; it is not a true lobe but rather a mere anatomically separated part of the upper lobe of the right lung.

$$\textbf{Hence, the correct option is (A)}$$

• Functional Residual Capacity (FRC) is the volume of air that will remain in the lungs after a normal expiration. 
• This includes expiratory reserve volume plus the residual volume i.e., 1100 ml plus 1200 ml or 2300 ml.
• So, the correct answer is '2300 ml'
  

• NO produces the same failure to absorb oxygen into the blood as carbon monoxide (CO). However, since NO is only slightly soluble in water, it poses no real threat except to infants and very sensitive individuals.
•  High temperature combustion can convert sulfur in fuel to $$SO_2$$ and $$SO_3$$. $$SO_2$$ is toxic and forms sulfurous acid when dissolved in water. 
• Both of these acids can form solid particles by reacting with ammonia in air. $$SO_2$$ and $$SO_3$$ also contribute to pH (acidity) changes in water, which can adversely affect both land and aquatic life.
•  At room temperature, sulfur dioxide is a non-flammable, colorless gas that is soluble in water and heavier than air. Sulfur dioxide has a (median lethal dose) $$LD_{50}$$ of 3000 ppm for mice.