Breathing and exchange of gases practice · Mixed difficulty

Option A (Alveoli) is correct because alveoli are the primary sites of gas exchange between air and blood in the lungs.

Option A (5) is correct because the trachea divides into the right and left primary bronchi at the level of the 5th thoracic vertebra.

Option C (${O_2}$ tension is low and $C{O_2}$ tension is high) is correct because these conditions promote the dissociation of oxygen from hemoglobin at the tissue level.

Option C (CO) is correct because carbon monoxide binds to hemoglobin with a much higher affinity than oxygen, forming a stable compound and preventing oxygen transport.

Option C ($pCO_2$ in tissues – 40 mm Hg) is the mismatch because the partial pressure of $CO_2$ in tissues is higher than 40 mm Hg.

Option C (A-$\mathrm{C}{\mathrm{O}_2}$, B-breathing, C-respiration) is correct because the process involves exchanging oxygen from the atmosphere with carbon dioxide produced by cells, which is called breathing or respiration.

Option C (RBC) is correct because carbonic anhydrase, the enzyme that catalyzes the conversion of carbon dioxide and water to carbonic acid, is primarily found in red blood cells.

Option B (Earthworms) is correct because earthworms use their moist skin (cuticle) for gas exchange.

Option D (Epiglottis) is correct because the epiglottis prevents food from entering the trachea during swallowing, and improper movement can lead to coughing.

Option D (Transport ${O_2}$ the cells) is correct because cellular respiration requires a continuous supply of oxygen to the cells.

Option B (${N_2}$) is correct because nitrogen is an inert gas and does not directly participate in the regulation of respiration rhythm.

Option B (Statement I is correct but Statement II is wrong) is correct because expiratory capacity depends on the volume of air expired, and expiratory capacity includes tidal volume and expiratory reserve volume, not inspiratory reserve volume.

Option C (Neural system) is correct because the respiratory rhythm is primarily controlled and modulated by neural centers in the brain.

The incorrect match is B (Volume of air remaining in the lungs even after a forcible expiration – 1000 – 1100 mL) because the residual volume is actually around 1100-1200 mL.

Option A (If both Assertion and Reason are true and Reason is the correct explanation of Assertion) is correct because the reason correctly explains the assertion.

Option C (20-25 %) is correct because 20-25% of carbon dioxide is transported by RBCs as carbaminohemoglobin.

Option C (Nostrils – Pharynx – Larynx – Trachea – Bronchi – Bronchioles – alveoli) is correct because it represents the correct sequence of air passage during breathing.

Option D (All of these) is correct because high partial pressure of oxygen, low partial pressure of carbon dioxide, and low hydrogen ion concentration (high pH) all favor the formation of oxyhemoglobin.

Option C (inability to respire) is correct because fish rely on gills to extract oxygen from water, and they cannot efficiently obtain oxygen from the air.

Option A (Arachnids) is correct because book lungs are a characteristic respiratory structure found in arachnids.

Option D (Some snakes) is correct because some species of snakes have only one functional lung, while the other is reduced or absent.

Option A (Anoxia) is correct because anoxia refers to a complete lack of oxygen, which would inhibit the respiratory center.

Option B (Haemoglobin is necessary for transport of oxygen and carbonic anhydrase for transport of carbon dioxide) is correct because haemoglobin binds and transports oxygen, while carbonic anhydrase facilitates the conversion of carbon dioxide into bicarbonate for transport.

Option A (Cockroach) is correct because cockroaches have an open circulatory system and use a tracheal system for oxygen transport, not blood with respiratory pigments.

Option A (TLC) is correct because Total Lung Capacity (TLC) includes the residual volume.

Option B (Expiration) is correct because relaxation of the diaphragm and intercostal muscles decreases the thoracic volume, leading to expiration.

Option B (${O_2}$ binds with RBC) is correct because oxygen binds to hemoglobin within red blood cells to form oxyhemoglobin.

Option B (vital capacity) is correct because vital capacity is the maximum amount of air that can be expired after a maximal inspiratory effort.

Option B (Low temperature and high pH) is correct because these conditions increase hemoglobin's affinity for oxygen, shifting the curve to the left.

Option C (If Assertion is true but Reason is false) is correct because aerobic respiration involves gas exchange at the lungs and tissues, but the reason incorrectly describes the exchange process.