Which class of enzymes catalyzes the covalent bonding of two substrates?

The enzyme which converts sucrose into glucose and fructose is:

Enzymes concerned with the transfer of electrons are known as:

Which of the following is not an enzyme?

Some nucleic acids behave like enzymes; these are called .........

Name the scientist who for the first time isolated and purified the enzyme urease in crystalline form from Jack bean (Canavalia ensiformis).