The dissociation curve is associated with

The graph plotted between the percentage saturation of hemoglobin with oxygen and the partial pressure of oxygen $(pO_2)$ is known as:

If haemoglobin is replaced by haemocyanin,the blood will carry

$A$ major percentage $(97 \%)$ of $O_{2}$ is transported by RBCs in the blood. How is the remaining percentage $(3 \%)$ of $O_{2}$ transported?

$A = CO_2$ is carried in the plasma mainly as $HCO_3^-$ ions.
$R =$ Carbonic anhydrase catalyzes the formation of $HCO_3^-$ ions.

The following statements refer to the transportation of gases. Read them carefully and choose the correct option containing the incorrect statements.
$(i)$ After leaving the lungs, each litre of blood contains about $20 \ ml$ of oxygen.
$(ii)$ When $PCO_2$ rises, the affinity of haemoglobin for oxygen is increased.
$(iii)$ Each litre of arterial blood contains about $4 \ ml$ of $CO_2$.
$(iv)$ The role of oxygen in the regulation of respiratory rhythm is quite significant.