Question

The enzyme that converts starch into maltose is called:
(A) Zymase
(B) Maltase
(C) Invertase
(D) Amylase

Answer 1

Hint: Starch is a polysaccharide and it is made up of two parts, one is helical amylose and the other is amylopectin. Generally, we name the enzyme that degrades certain compounds by putting the suffix –ase behind the name of the compound that gets degraded.

Complete step by step answer:
- It is a rule in the nomenclature of the enzymes that if they convert big molecules into smaller ones, then the suffix ‘-ase’ is used behind their name. Let’s see which enzyme can convert starch into maltose.
- Starch is made up of amylose chains. So, the enzyme that degrades amylose chains is called amylase. So, enzyme amylase degrades the starch molecules into sugars like maltose.
- Enzyme amylase is found in the saliva of humans and it is responsible for the digestion of the starch eaten by us.
- Zymase catalyses the degradation of sugar (sucrose). It produces ethanol and carbon dioxide as the end products. Zymase was first isolated from the yeast cell.
- The enzyme that degrades the maltose molecule is called maltase. It degrades maltose into two glucose units. This enzyme is found in plants, bacteria and yeast.
- Invertase is the enzyme that hydrolyses the sucrose into two monosaccharide units, glucose and fructose. The name of this enzyme was given as an invertase because the optical rotation of the mixture gets inverted from positive value to negative value during the reaction.
So, the correct answer to this question is (D).

Note: Note that diastase can also convert starch into maltose. So, it can also degrade the starch molecule. Diastase was the first enzyme discovered by the scientists. The enzyme diastase can be extracted from the sources like saliva, plants and milk.