What is true about RBCs in humans?
 

1.	They carry about 20-25 per cent of  CO2
2.	They transport 99.5 per cent of O2
3.	They transport about 80 per cent oxygen only and the rest 20 per cent of it is transported in dissolved state in blood plasma
4.	They do not carry  CO2  at all

An increase from pH 7.2 to pH 7.4 around hemoglobin causes:

1. hemoglobin to release all bound oxygen molecules.

2. an increase in the affinity of hemoglobin to bind oxygen molecules.

3. hemoglobin to denature.

4. an increase in the binding of H⁺ by hemoglobin.

Increased asthmatic attacks in certain seasons are related to:

1. hot and humid environment

2. eating fruits preserved in tin containers

3. inhalation of seasonal pollen

4. low-temperature 

The 'blue baby' syndrome results from:

1. excess of chloride

2. methaemoglobin

3. excess of dissolved oxygen

4. excess of TDS (Total Dissolved Solids)

The majority of carbon dioxide produced by our body cells is transported to the lungs:

1. dissolved in the blood

2. as bicarbonates

3. as carbonates

4. attached to haemoglobin

Pneumotaxic centre which can moderate the functions of the respiratory rhythm centre is present at:

1. Pons region in brain

2. Thalamus

3. Spinal cord

4. Right cerebral hemisphere

Haemoglobin is:

1. An oxygen carrier in human blood

2. A protein used as a food supplement

3. An oxygen scavenger in root nodules

4. A plant protein with high lysine content

The exchange of gases in the alveoli of the lungs takes place by:

1. osmosis

2. simple diffusion

3. passive transport

4. active transport

Dead space air in man is:

1. 500 mL

2. 150 mL

3. 250 mL

4. 1.5 L

Amount of CO₂ in expired air is about:

1. 0.04%

2. 0.03%

3. 4.5%

4. 21%