Haemoglobin has maximum affinity with

Oxygen is transported to every cell of the body through:

Why is $CO$ (carbon monoxide) poisonous to humans?

What is the shape of the oxygen dissociation curve of hemoglobin?

Which of the following conditions is not responsible for shifting the oxygen-hemoglobin dissociation curve towards the left?

What are $P$ and $Q$ in the given reaction?
$CO _2+ H _2 O \underset{Q}{\stackrel{P}{\rightleftharpoons}} H _2 CO _3 \underset{Q}{\stackrel{P}{\rightleftharpoons}} HCO _3^{-}+ H ^{+}$