FREE NEET Biology Practice MCQ Test: Breathing And Exchange Of Gases Exercise 1 Questions Answers With Detailed Explanations [PDF]

Answer: (a)

Answer: (b)

Answer: (d)

Answer: (c)

Answer: (a)

$CO_{2}$ enters RBC and reacts with water to form carbonic acid. Carbonic acid dissociates to form bicarbonate and hydrogen ions. Some bicarbonate ions are transported in erythrocytes while some diffuse into the blood plasma. The exit of bicarbonate ions change the ionic balance between the plasma and erythrocytes. To restore this balance chloride ions diffuse from plasma into erythrocytes. Due to this the pH of blood is maintained.

Answer: (c)

During the transport of $CO_{2}$ through the blood, bicarbonate ions diffuse out of RBCs while chloride ions from plasma enter the RBCs to maintain ionic equilibrium. This is called chloride shift.

Answer: (d)

Spirometer is a device used to measure the volume of air involved in breathing movements and it also helps in clinical assessment of pulmonary functions.

Stethoscope is a medical device used for listening to the internal sounds of an animal or human body.

Hygrometer is a device used for measuring the moisture content in the atmosphere, or humidity.

Sphygmomanometer is a device that is used to measure blood pressure.

Answer: (b)

All animals require a medium for cellular respiration. Cellular respiration is the process of oxidizing food molecules, like glucose, to carbon dioxide and water. The energy released is trapped in the form of ATP for use by all the energy-consuming activities of the cell.

Answer: (c)

When systemic arterial blood flows through capillaries, carbon dioxide diffuses from the tissues into the blood. Some carbon dioxide is dissolved in the blood. Some carbon dioxide reacts with haemoglobin to form carbaminohaemoglobin. The remaining carbon dioxide is converted to bicarbonate and hydrogen ions. Most carbon dioxide is transported through the blood in the form of bicarbonate ions.

Answer: (d)

Answer: (c)

Answer: (c)

In certain industries, especially those involving grinding or stone breaking so much dust is produced that the defence mechanism of the body cannot fully cope with the situation. Long exposure can give rise to inflammation leading to fibrosis (proliferation of fibrous tissues) and thus causing serious lung damage. Workers in such industries should wear protective masks.

Answer: (c)

In the disease emphysema, alveolar surface area is reduced due to destruction of alveolar walls.

Answer: (a)

Inhaled air has not yet exchanged gases with lung capillaries, therefore it contains the highest concentration of oxygen.

Answer: (a)

Answer: (a)

Thin layer of water on the inner surface of alveoli serves to contract the alveoli and makes them behave like unfilled balloons that resist inflation. This would mean tremendous effort to inhale and expand the alveoli and therefore to overcome this, cells of the alveoli secrete pulmonary surfactant to decrease the surface tension of water lining the alveoli.

Answer: (d)

Answer: (d)

Answer: (d)

Trachea is a straight tube which extends up to the mid-thoracic cavity. The trachea divides at the level of 5th thoracic vertebra into right and left primary bronchi. Each bronchus undergoes repeated divisions to form secondary and tertiary bronchi and bronchioles. They finally end up in very thin terminal bronchioles. The tracheae, bronchi and the initial bronchioles are supported by incomplete cartilaginous rings.

Answer: (d)

Myoglobin has the greatest affinity for oxygen and does not unload the oxygen until very low partial pressures of oxygen (below 20 mmHg). Foetal haemoglobin has a higher affinity for oxygen than adult haemoglobin, thus facilitating the transfer of oxygen from maternal haemoglobin to fetal, haemoglobin at the placenta. When respiration is occurring a fast rate, more oxygen is needed. High levels of respiration are associated with high levels of carbon dioxide, hence the affinity of haemoglobin for oxygen decreases at higher carbon dioxide partial pressures so that oxygen can be released to respiring tissues.