Test: Respiratory Organs & Human Respiratory System

• The respiratory or gas-exchange surface consists of millions of small sacs, or alveoli, lined by a simple squamous epithelium.
• This epithelium is exceedingly thin to facilitate the diffusion of oxygen and CO₂. 
• The alveolar walls also contain cuboidal surfactant-secreting cells.
  

Hence, the correct option is A

NCERT Reference: Page no. 273 of topic “17.3 EXCHANGE OF GASES” of chapter 17 of NCERT

• A graph is plotted between oxygen concentration and percentage saturation of haemoglobin with this curve is called dissociation curve.
• Dissociation curve is sigmoid in shape.

Hence, the correct option is D.

NCERT Reference: Page no. 274 of topic “17.4.1 Transport of Oxygen” of chapter 17 of NCERT.

• The pharynx opens into the larynx by a slit-like aperture called the glottis, which is covered by a cartilaginous flap called the epiglottis.
• The epiglottis closes the glottis to prevent the entry of food particles during swallowing.
  

Hence, the correct option is C.

NCERT Reference: Page no. 269 of topic “17.1.1 Human Respiratory System” of chapter 17 of NCERT

A book lung is a type of respiration organ used for atmospheric gas exchange that is found in many arachnids, such as scorpions and spiders.

Hence, the correct option is D.

NCERT Reference: Page no. 268 of topic “17.1 RESPIRATORY ORGANS” of chapter 17 of NCERT.

• The respiratory system helps in the regulation of blood pH, gaseous exchange and also contains receptors of smell, produces vocal sound and filters inspired air.
• While the cardiovascular system protects against blood loss by the formation of blood clots.

Hence, the correct option is D

NCERT Reference: Page no. 269 of topic “17.1.1 Human Respiratory System” of chapter 17 of NCERT.

• Earthworms respire only through the moist skin which is permeable to gases and Leeches also breathe through the skin.
• Frogs don't respire always through the skin whereas Fishes respire through gills.

Hence, the correct option is C.

NCERT Reference: Page no. 268 of topic “17.1 RESPIRATORY ORGANS” of chapter 17 of NCERT.

• The volume of air remaining in the lungs even after a forcible expiration is called residual volume.
• This residual volume prevents the lungs from collapsing.

Hence, the correct option is B.

NCERT Reference: Page no. 272 of topic “17.2.1 Respiratory Volumes and Capacities” of chapter 17 of NCERT.

• The narrow tubes found inside the lungs are called bronchioles. 
• When we breathe, air travels from the nose or mouth, and goes down the trachea and reaches the part called the carina.
• From here the tube branches into two, creating two bronchi that lead to the left and right lung each.

From there onwards, the bronchi split into smaller and smaller bronchioles until it terminates in the alveoli where gas exchange occurs.​​​​​​​

Hence, the correct option is C.

NCERT Reference: Page no. 269 of topic “17.1.1 Human Respiratory System” of chapter 17 of NCERT.

• The pleural membranes are two layers of the serous membrane which enclose and protect the lung.
• The superficial layer is called the parietal pleura and lines the wall of the thoracic cavity.
• The deep layer is called the visceral pleura and covers the lungs themselves.

Hence, the correct option is B.

NCERT Reference: Page no. 269 of topic “17.1.1 Human Respiratory System” of chapter 17 of NCERT.

The trachea serves as a passage for air, moistens and warms it while it passes into the lungs, and protects the respiratory surface from an accumulation of foreign particles.

Hence, the correct option is C.

NCERT Reference: Page no. 270 of topic “17.1.1 Human Respiratory System” of chapter 17 of NCERT.