Question 1

Respiration in insects is called direct because

Accepted Answer

Insects have a network of tubes (tracheal tubes) to transport atmospheric air within the body. These openings lead to trachae. The cells exchange O2​/CO2​ directly with the air in the spiracles present on insects body.Spiracle

Question 2

A person suffers punctures in his chest cavity in an accident, without any damage to the lungs its effect could be

Accepted Answer

The movement of air into and out of the lungs is carried out by creating a pressure gradient between the lungs and the atmosphere. The pressure within the lungs is less than the atmospheric pressure so there is a negative pressure in the lungs with respect to atmospheric pressure. The puncture in the chest affects this pressure gradient maintained by the lungs and thus may cause cessation of breathing.

Question 3

It is known that exposure to carbon monoxide is harmful to animals because

Accepted Answer

Haemoglobin consist of a protein globin and pigment here. The four portion of iron in name combine with molecule of oxygen. It is an easy reversible reaction to form oxyhaemoglobin.Hb+O2​⇌HbO2​Whereas, the complex formed by the reaction of carbon monoxide and haemoglobin is incredibly strong (Haemoglobin) Hb+CO​⟶ (Carboxy  haemoglobin) ​HbCO​As a result of this strong between the haemoglobin and carbon monooxide the haemoglobin looses its affinity to oxygen thus may lead to choking or even death.

Question 4

Mark the true statement among the following with reference to normal breathing

Accepted Answer

Inspiration is a active process whereas expiration is a passive process. Inspiration occur when the muscles of diaphragm contract to increase the overall volume of thoracic cavity.Thus the pressure within the lungs (intra-pulmonary pressure) is less in comparison to the atmospheric pressure, i.e., there is a negative pressure in the lungs with respect to atmospheric pressure. As the muscles use energy for contraction inspiration is called active process.Whereas, during the expiration diaphragm muscles relax without the use of energy intra-pulmonary pressure becomes higher than the atmospheric pressure and air noshes out. Thus, it is a passive process.

Question 5

A person breathes in some volume of air by forced inspiration after having a forced expiration. This quantity of air taken in is

Accepted Answer

The maximum volume of air that a person can breathe in after forced expiration or the maximum volume of air that a person can breathe out after forced inspiration is called vital capacity.VC=IRV (Inspiratory reserve volume) ​+ERV (Expiratory reserve volume) ​+TV (Tidal volume) ​ The value of vital capacity varies from 3400 mL to 4800 mLOn the other hand, tidal volume is the air inspired or expired during normal breathing. Total lung capacity is the volume of air present in lungs and respiratory passage after maximum inspiration. Whereas, inspiratory capacity is total volume of air that a person can inspire after normal inspiration.

Question 6

Mark the incorrect statement in context to O2​ binding to Hb

Accepted Answer

Vital Capacity is the amount of air that a person forcefully breathes in. Binding of oxygen with haemoglobin is related to the partial pressure exhibited by O2​. In the alveoli, higher partial pressure of O2​, lower partial pressure of CO2​, and less H+ concentration facilitate the formation of oxyhaemoglobin.

Question 7

Mark the correct pair of muscles involved in the normal breathing in humans.

Accepted Answer

The diaphragm and a specialised set of muscles, called external muscles present between the ribs are involved in the normal breathing in humans. They are involved in generating pressure gradient of air between the lungs and the atmosphere, so as to facilitate the intake of air.

Question 8

Which of the following does not occur during breathing?

Accepted Answer

Diffusion of gases is a physical phenomenon that takes place between the tissue and blood vessels, and does not occur during breathing whereas bringing air to the body temperature, its cleaning and warming occurs during the process of breathing.

Question 9

Incidence of emphysema a respiratory disorder is high in cigarette smokers. In such cases

Accepted Answer

Emphysema is a chronic disorder in which alveolar walls are damaged due to the infection or autosomal distersion. It is a respiratory disorder caused by cigarette smoking and inhalation of other smoke or toxic substances over a period of time.

Question 10

Respiratory process is regulated by certain specialised centres in the brain. One of the following listed centres can reduce the inspiratory duration upon stimulation.

Accepted Answer

Pneumotaxic Centre: Located in the dorsal part of pons varolii of the brain can reduce the duration of inspiration and thus alter the respiratory rate.Apneustic Centre: Whereas is located in the lower part of pons varoli is responsible for promoting inspiration process.Chemosensitive Centre: is situated adjacent to the rhythm centre which is highly sensitive to CO2​ and hydrogen ions. Increase in CO2​ and H+in body and activates this centre for the elimination of CO2​ and HMedullary Inspiratory Centre is a specialised region present in medulla of the brain. and is primarily responsible for regulating the respiratory rhythm.

Question 11

CO2​ dissociates from carbamino haemoglobin when

Accepted Answer

When, the pCO2​ is low and pO2​ is high as in the lung alveoli, dissociation of CO2​ from carbamino-haemoglobin takes place, CO2​ which is bound to haemoglobin from the tissue is delivered at the alveoli, to maintain the concentration of CO2​ thus increasing pCO2​Exchange of gases takes place between tissue capillary and tissue cells. Capillary cells with high pO2​ causes diffusion of O2​ into tissue cells via tissue fluid on the other hand high pCO2​ in the tissue cells causes diffusion of CO2​ into tissue capillary via tissue fluid.

Question 12

In breathing movements, air volume can be estimated by

Accepted Answer

(d) Spirometer is the 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 the internal sounds of an animal or human body.Hygrometer is a device used for measuring the moisture content in the atmosphere, i.e., humidity.Sphygmomanometer is a device that is used to measure blood pressure.

Question 13

From the following relationships between respiratory volume and capacities, mark the correct option.(i) Inspiratory Capacity (IC) = Tidal Volume + Residual Volume(ii) Vital Capacity (VC) = Tidal Volume (TV) + Inspiratory Reserve Volume (IRV) + Expiratory Reserve Volume (ERV).(iii) Residual Volume (RV) = Vital Capacity (VC) - Inspiratory Reserve Volume (IRV)(iv) Tidal Volume (TV) = Inspiratory Capacity (IC) - Inspiratory Reserve Volume (IRV)Codes

Accepted Answer

(i) Inspiratory Capacity (IC) = Tidal Volume + Inspiratory Reserve Volume (TV + IRV).(ii) Vital Capacity (VC): Tidal Volume + Inspiratory Reserve Volume + Expiratory Reserve Volume. (TV + ERV + IRV)(iii) Residual Volume (RV): Volume of air remaining in the lungs after a forcible expiration.(iv) Tidal Volume (TV): Volume of air inspired or expired during a normal respiration.

Question 14

The oxygen-haemoglobin dissociation curve will show a right shift in case of

Accepted Answer

A sigmoid curve obtained when percentage saturation of haemoglobin with O2​ is plotted against the pO2​.The oxygen haemoglobin dissociation curve is shifted to right under following condition. (i) Decrease in partial pressure of oxygen. (ii) Increase in partial pressure of carbon oxide. (iii) Increase in hydrogen concentration. (iv) Decrease in pH activity. (v) Increased body temperature.

Question 15

Match the following columns.

Accepted Answer

Earthworms respire through their moist cuticle and aquatic arthropods, respire through the trachea. Fishes respire through gills, and birds/reptiles respire through lungs.

Question 16

Define the following terms? (a) Tidal volume (b) Residual volume (c) Asthma

Accepted Answer

(a) Tidal Volume (TV) is the volume of air inspired or expired during normal breath. This is about 500 mL, i.e., a healthy man inspire or expire about 6000 to 8000 mL of air per minute.(b) Residual Volume (RV) is the volume of air remaining in the lungs even after a forcible expiration. It is about 1100 mL to 1200 mL. (c) Asthma: It is a disease caused due to an allergic reaction to foreign substances. The major symptoms are difficulty in breathing causing wheezing and coughing. Due to the inflammation of bronchi.

Question 17

A fluid filled double membranous layer surrounds the lungs. Name it and mention its important function.

Accepted Answer

A fluid filled double membranous layer that surrounds the lungs is called pleura, and fluid is pleural fluid in between them. The outer pleural membrane is in close contact with the thoracic lining whereas, the inner pleural membrane is in contact with the lung surface. These collectively reduce friction on lung's surface.

Question 18

Name the primary site of exchange of gases in our body?

Accepted Answer

The primary site for the exchange of gases in our body is alveoli. There are 300 millions of alveoli collectively in both the lungs. These alveoli have very thin wall consisting of squamous epithelium. With extensive network of blood capillaries.The presence of blood capillaries in the alveoli, result in easy exchange of gases. Each alveolus is also called as miniature lung.

Question 19

Cigarette smoking causes emphysema. Give reason.

Accepted Answer

Emphysema is a chronic disorder of respiratory system, where inflation or abnormal distension of alveolar wall occurs. Cigarette smoking and the inhalation of other smoke or toxic substances over a period of time causes the damaging of septa between the alveoli, and of its elastic tissue is replaced by the connective tissue in lungs. Hence, the respiratory surface decreases, thus causing the emphysema. It causes shortness of breath, production of sputum, chronic bronchitis, etc.

Question 20

What is the amount of 02​ supplied to tissues through every 100 mL of oxygenated blood under normal physiological conditions?

Accepted Answer

Every 100 mL of oxygenated blood can deliver around 5 mL of O2​ to the tissue under normal physiological conditions.

Chapter 17 : Breathing and Exchange of Gases