When a man inhales air containing normal concentration of O₂ as well as CO he suffers from suffocation because

(1) CO reacts with O₂ reducing its percentage in air

(2) haemoglobin combines with CO instead of O₂ and forms carboxyhaemoglobin

(3) CO affects diaphragm and intercostal muscles

(4) CO affects the nerves of the lungs.

Respiration is controlled by

1. medulla oblongata

2. cerebellum

3. hypothalamus

4. cerebrum

Chemosensitive area of respiratory centre medulla is affected by

1. less CO₂ and H⁺ ions

2. less O₂ and H⁺ ions

3. excess CO₂ and H⁺ ions

4. excess O₂ and H⁺ ions.

Oxygen binding to haemoglobin in blood is

1. directly proportional to the concentration of CO₂ in the medium

2. inversely proportional to the concentration of CO₂ in the medium

3. directly proportional to the concentration of CO in the medium

4. independent of the concentration of CO in the medium.

Carbon dioxide (CO₂) diffuses into blood from tissue site and passes to alveolar site in the form of

1. bicarbonate; 70%

2. bicarbonate; 20 - 25%

3. carbaminohaemoglobin; 60 - 70%

4. carbaminohaemoglobin; 7%.

Hiccups can be best described as

(1) forceful sudden expiration

(2) forceful contraction of intercostal muscles during deep breathing

(3) vibration of the soft palate during breathing while sleeping

(4) jerky incomplete inspiration.

The given figure shows schematic plan of blood circulation in humans with labels A to D. Identify the labels along with their functions and select the correct option.

(1) C - Vena Cava - takes blood from body parts to right atrium, P_CO2 = 45 mm Hg

(2) D - Dorsal aorta - takes blood from heart to body parts, P_O2 = 95 mm Hg

(3) A - Pulmonary vein - takes impure blood from body parts to heart, P_O2 = 60 mm Hg

(4) B - Pulmonary artery - takes blood from heart to lungs, P_O2 = 90 mm Hg.

The volume of 'anatomical dead space’ air is normally

(1) 230 mL

(2) 210 mL

(3) 190 mL

(4) 150 mL.

Oxyhaemoglobin dissociates into oxygen and deoxyhaemoglobin at

1. low O₂, pressure in tissue

2. high O₂, pressure in tissue

3. equal O₂, pressure inside and outside tissue

4. all times irrespective of O₂, pressure

A person sitting at rest experiences a temporary cessation of breathing after forced deep breathing for a few minutes.This is due to:-

(1) too much CO₂ in the blood

(2) too much O₂ in the blood

(3) very little CO₂ in the blood

(4) both high O₂ and very little CO₂ in the blood