Cyanide is an inhibitor of complex IV (in ETS) and other heme-containing enzymes of mitochondria. Thus, cyanide blocks ATP production in the cells.

Spirometry is the process of recording the changes in the volume and movement of air in and out of the lungs and the instrument used for this purpose is called spirometer or respirometer.

• The respiratory tract carries air from the mouth and nose to the lungs.
• In the lungs, the gases oxygen and carbon dioxide are exchanged between the alveoli and the capillaries. 
• Exhaled air contains less oxygen and more carbon dioxide, Hence, The air we breathe out contains more carbon dioxide.

• The diaphragm is a thin skeletal muscle that sits at the base of the chest and separates the abdomen from the chest.
•  It contracts and flattens when you inhale. 
• This creates a vacuum effect that pulls air into the lungs.
•  When you exhale, the diaphragm relaxes and the air is pushed out of lungs. Hence, diaphragm forms the floor of the chest cavity.

• Respiration includes two processes: inhalation and exhalation.
• Inhalation (also known as inspiration) occurs when air or other gases enter the lungs.
•  And exhalation is the process by which the body expels carbon dioxide. Hence, Taking in of carbon dioxide is inhalation is a wrong statement.

Component                        Inspired air         Expired air
  $CO _2$                                    0.04%                   4%
Because carbon dioxide is released at the alveolar surface during the gaseous exchange between blood and alveoli.

Component              Inspired air            Expired air
Nitrogen                      79%                     79.6%

Inspired air contains more oxygen whereas, the expired air contains more of carbon dioxide content as well as water vapours. Air enters with oxygen is diffused with carbon dioxide leading to the exchange of gases.

The act of breathing air into the body the help of lungs is called inhalation. By this process, fresh air enters into the lungs that contain large amount of oxygen.

The act of breathing out air from the lungs is called as Exhalation. By this process, the foul air i.e, (containing ${ CO } _{ 2 }$) is expelled out of the lungs.

The diaphragm is a dome-shaped, muscular and membranous structure that separates the chest and abdominal cavities in mammals. It is the principal muscle of respiration that maintain the volume of air in the chest cavity during breathing.

Humans have lungs to carry out respiration. Lungs are ingrowths of the body wall and correct to the outside by a series of tubes and small openings.

During inspiration, the diaphragm moves down. The contraction of muscle fibers of the diaphragm causes it to become flat and lowered down thereby increasing the volume of the thoracic cavity in anteroposterior axis, in rabbit or lengthwise in man.

(a) At high altitude, $PO _2$ of alveolar air falls because of low $O _2$ tension of tissues. So, $O _2$ is absorbed very quickly from alveoli, thus, increasing breathing rate. Heart beat also increases to supply required amount of O2 to tissues.

(c) The partial pressure of $O _2$ will fall drastically along with the fall in barometric pressure, So hypoxia will develop which causes increase in the rate of respiration.

(c) Spirometry is the process of recording the changes in the volume movement of air into and out of lung and the instrument used for the purpose is called spirometer or respirometer.

Exhalation is a passive process because of the elastic properties of the lungs. During forced exhalation, internal intercostal muscles which lower the rib cage and decrease thoracic volume while the abdominal muscles push up on the diaphragm which causes the thoracic cavity to contract. 

Carbon dioxide is a waste product of the body. It is majorly exhaled out by the body so that it will reduce the competition to gets bind to the haemoglobin with oxygen. It is saturated with water vapours.

Blood that is low in oxygen concentration and high in carbon dioxide. The rate of diffusion of a gas is proportional to its partial pressure within the total gas mixture. The lungs are never completely empty: There is always some air left in the lungs . At high altitudes, Patm decreases but concentration does not change. So, the correct option is "B" (Increases).

• The diaphragm is the type of skeletal muscle found in mammals which plays a major role in respiration. It is a dome-shaped structure and moves in and out at the time of respiration. Its muscles separate the thoracic cavity having heart and lungs from the abdominal cavity. 
• During inhalation, the diaphragm contracts and chest cavity increases to get more oxygen while in exhalation diaphragm relaxes and the chest cavity decreases and releases carbon dioxide.

The ribs and the various muscles of respiration aid in both inspiration and expiration, which require changes in the pressure within the thoracic cavity. The important respiratory muscles are the diaphragm, the external intercostal and the internal intercostal muscles. The ribs and the respiratory muscles work to achieve this by changing the dimensions of the thoracic cavity.
When a person inhales, the rib cage move out and up in order to accommodate the incoming air. On the other hand, when a person exhales, the rib cage move in, in order to expel the carbon dioxide. Both the external intercostal muscles and the internal intercostal muscles elevate the ribs, thus increasing the width of the thoracic cavity, while the diaphragm contracts to increase the vertical dimensions of the thoracic cavity, and also aids in the elevation of the lower ribs. The muscles that connect the ribs together ensure that the diaphragm can expand and contract appropriately as air is breathed in and expelled. Thus, in mammals, breathing depends more on ribs and their muscles for breathing than diaphragm.

• Spiracles are openings on the surface of some animals, which usually lead to respiratory systems. 
• The spiracle is a small hole behind each eye that opens to the mouth. Insects and some more derived spiders have spiracles on their exoskeletons to allow air to enter the trachea.
•  In the respiratory system of insects, the tracheal tubes primarily deliver oxygen directly into the animals' tissues. 
• The spiracles can be opened and closed in an efficient manner to reduce water loss. Hence, The respiratory organs in cockroach are spiracles.

Diaphragm is a muscular and tendinous sheath that closes the opening between thorax and abdomen and is pierced by structures that pass between these two regions of the body. The diaphragm is the primary muscle of respiration. Diaphragm is the primary respiratory muscle of the body. It, on contraction, increases the vertical diameter of the chest cavity by pulling its central tendon downwards. In this way, the lungs get extra space to expand and air rushes into them. 

In birds, the air sacs permit unidirectional flow of air through the lungs. Unidirectional flow means that air moving through bird lungs is largely 'fresh' air & has a higher oxygen content. So, the correct option is 'birds'.