MCQs on Respiratory System

Ans. a) Skin

Explanation. Earthworms' skin is permeable to gases. As the earthworms do not possess any spiracles, lungs, or gills, they can only breathe through the skin. The moist nature of the skin of an earthworm helps in the easy absorption of oxygen.

Ans. b) Filtering the air that we breathe

Explanation. The trachea acts as a passage for air which warms and moistens the air when it is passed through the lungs. It then protects the respiratory surface from the accumulation of foreign particles. The trachea has a layer of mucous membrane that is made up of cells having small hair-like projections that are known as cilia. Hence, the trachea helps to filter the air that we breathe.

Ans. d) Alveoli

Explanation. Alveoli are the small scale of air that are mainly responsible for the exchange of gases in our body.

The larynx is our voice box while the pharynx is a common passage for both air and food.

The trachea, on the other hand, is simply our windpipe.

Ans. a) Involuntary breathing is controlled by neurons that are located in the pons and the medulla.

Explanation. Involuntary actions are the ones that are not directly under our control. Breathing is a process that is meant to be carried out even during our sleeping time. The intercostal muscles and the diaphragm are controlled by the neurons that are present in the pons and medulla. Therefore, involuntary breathing is controlled by neurons that are located in the pons and the medulla.

Ans. a) Trachea

Explanation. The windpipe, also known as the trachea, is a vital part of the respiratory system that is the passage of air from the mouth or nose to the lungs. It allows the passage of the air as it extends from the larynx. It further branches into 2 primary bronchi.

Ans. c) Mediastinum

Explanation. The cavity between both the pleural sacs of our lungs is referred to as the mediastinum. It separates the lungs in the thoracic cavity. This cavity contains the oesophagus, heart, trachea, remaining parts of the thymus, thoracic duct of the lymphatic system, etc.

The pleura or pleural cavity is a narrow space that exists between the parietal pleura and visceral pleura. It encloses each of our lungs.

The thoracic cavity is an air tight chamber that is surrounded by the thoracic vertebrae on the dorsal side.

Ans. c) Respiration

Explanation. During the process of respiration, heat energy is formed. We can also understand respiration as the process through which energy from glucose is released. It is an exothermic process which means it releases heat.

Ans. b) Lungs

Explanation. The exchange of gases in aves takes place in the Lungs. Unlike mammals, in the lungs of the aves, the air only flows in one direction. Thus, with the help of the air sacs, they are able to exchange gases or take in oxygen even during exhalation. Birds can breathe at a higher elevation than mammals as they have a highly efficient lung structure.

Ans. c) Protection against the loss of blood

Explanation. The respiratory system helps in the regulation of the pH of the blood and also has the receptors for the sense of smell. It helps in producing vocal sounds and filtering the inhaled air while the cardiovascular system helps in the protection of the human body against the loss of blood through the formation of blood clots.

Ans. b) Dorsal respiratory group

Explanation. Both the inspiratory and expiratory neurons are present in the ventral respiratory group which further helps in controlling the forced breathing. On the other hand, the dorsal respiratory group only has inspiratory neurons and thus are responsible for controlling normal breathing.

Ans. c) It facilitates the exchange of gases between the bloodstream and the alveoli

Explanation. Internal respiration refers to the process wherein the exchange of gases such as oxygen and carbon dioxide takes place between the bloodstream and alveoli of an organism. In human beings, internal respiration takes place between the bloodstream and alveoli. External respiration, on the other hand, takes place between the alveoli and the atmosphere.

Ans. c) Total lung capacity

Explanation. Total lung capacity refers to the maximum volume of air that is contained in the lung after a full forced inhalation. For a healthy man, the total lung capacity is estimated to be 6000 ml. Total Lung Capacity (TLC) is calculated by adding up the four primary lung volumes such as Inspiratory Reserve Volume (IRV), Tidal Volume (TV), Expiratory Reserve Volume (ERV), and Residual Volume (RV).

Ans. d) Cilia

Explanation. Cilia are slender, small, hair-like structures that are present on the surface of all the cells of a mammal. They play a very vital role in locomotion. They are used to filter out and keep the mucus and dirt away from the lungs allowing us to easily breathe without any irritation.

Ans. b) Carbon dioxide

Explanation. Respiration refers to the biochemical process through which the glucose that is present in the cell is broken down into simpler substances to further release energy and carbon dioxide. Therefore, oxygen is used during this process and the products include energy, water, and carbon dioxide gas which is exhaled.