The oxygen-hemoglobin dissociation curve shifts to the right due to a decrease in which of the following?

What are the favorable conditions in the alveoli for the formation of oxyhemoglobin?

Body tissues obtain $O_2$ from hemoglobin. The dissociation of oxyhemoglobin in the tissues is primarily caused by which of the following conditions?

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.

What are the major transport mechanisms for $CO_{2}$? Explain.

Name the enzymes $A$ and $B$ in the following equation:
$CO _2+ H _2 O \underset{B}{\stackrel{A}{\rightleftharpoons}} H _2 CO _3 \underset{B}{\stackrel{A}{\rightleftharpoons}} HCO _3^{-}+ H ^{+}$