Respiration and Gas Exchange

It is not proper to breathe through our mouth because most of the dust particles can enter our body along with the air we breathe in. But breathing through nose does have this because nose has hair present which traps the dust particles.

Anatomical dead space refers to the volume of the respiratory tract where gas exchange does not occur, such as the trachea and bronchi.

Gas exchange in the alveoli occurs via simple diffusion, where gases move from an area of higher partial pressure to an area of lower partial pressure across the respiratory membrane.

Respiratory membrane must be semi- permeable in nature to allow the passage of small molecules and ions. It should also support the process of diffusion. Only large molecules are transported using channels or porins. In root, the ascent of sap takes place through simple diffusion. If cell membrane was not semi permeable then it could have never happen. If it was permeable or impermeable then it is difficult for cell to survive. Thus, option C is correct.

Air enters the body through the nose and mouth. After the nose and mouth air goes through the pharynx or throat. After the pharynx, air goes into the larynx or voice box. 

Respiratory membrane must be semi- permeable in nature to allow the passage of small molecules and ions. It should also support the process of diffusion. only large molecules are transported using channels or porins. In root, the ascent of sap takes place through simple diffusion. If cell membrane was not semi permeable then it could have never happen. If, it was permeable or impermeable then it is difficult for cell to survive. 

Smoking is a practice in which a substance is burned and the smoke is breathed in and absorbed into the bloodstream. Most commonly used substance is the dried leaves of the tobacco plant. Smoking is primarily practised for recreational drug use.
 The combustion of the dried plant leaves vaporizes and delivers active substances into the lungs where they are rapidly absorbed into the bloodstream and reach bodily tissue. 
Smoking generally has negative health effects, because smoke inhalation may cause effects on physiologic processes such as respiration.
Hence, the smoke inhaled by the respiratory system.
So, the correct option is ' the respiratory system'.

Puncturing the thoracic wall (pneumothorax) disrupts the negative intrapleural pressure required to keep the lungs inflated against their natural elastic recoil, leading to lung collapse and respiratory failure.

Actually, only about 350 mL of air (out of total 500 mL tidal volume) enters the lung alveoli for the exchange of gases. The remaining 150 mL fills the respiratory passage and is termed as dead air space because no exchange of gases takes place here.

The nasopharynx is the upper part of the pharynx, located behind the nasal cavity. It serves as a passage for air only, not food. The statement that internal nostrils open into it is correct, but the claim that it opens through the glottis into the trachea is incorrect; the glottis is the opening to the larynx, which is located below the oropharynx.

The epiglottis is a flap of cartilage that covers the opening of the larynx during swallowing. This prevents food and liquids from entering the respiratory tract.

• 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.

Alveoli are tiny, thin-walled air sacs in the lungs where the actual exchange of oxygen and carbon dioxide takes place between the lungs and the bloodstream via diffusion.