Proteins which catalyse biochemical reactions in the living world are known as

What is ribozyme?

Which of the following enzymes is $NOT$ regulated by calcium?

The following graph shows the effect of substrate concentration on enzyme activity. What does the $Y$-axis represent?

$X$: All enzymes act in a unidirectional manner.
$Y$: All enzymes are amphoteric in nature.

What does $Q$ represent in the given figure?