Question

Consider the given statements:
I. Maltose is also known as malt sugar.
II. Sucrose is also known as cane sugar.
III. Lactose is also known as grape sugar.
IV. Starch is also known as amylum.
The correct statement(s) is/are:
A. I,II and IV
B. I,II and III
C. II,III and IV
D. All

Answer 1

Maltose is a disaccharide. Carbohydrates can be monosaccharide, oligosaccharides and polysaccharides. Monosaccharides have only one type of unit forming the whole structure unlike that in disaccharide. In disaccharide there are two types of structural unit present that make up the whole structure of the compound.

Complete step-by-step answer: Maltose is formed by two glucose units which are joined with an $\alpha \left( {1 \to 4} \right)\;$bond. There is an isomer called isomaltose which is present in maltose. The two glucose molecules are joined together by the bond. Maltose is the two-unit member of the amylose homologous series, the key structural motif of starch. When alpha-amylase breaks down starch, it removes two glucose units at a time, producing maltose. Glucose has a hexose structure which is a monosaccharide with six carbon atoms.
Maltose is a reducing sugar. It is because the ring of one of the two glucose units has an aldehyde group which is free. The other ring present cannot free the aldehyde as it is used up in the formation of glycosidic bonds. This bond is the main bond formation which occurs in glucose.
We know that,
(I) Maltose is also known as malt sugar.
(II) Sucrose is also known as cane sugar.
(III) Lactose is also known as milk sugar.
(IV) Starch is also known as amylum.

This means that I, II and IV are correct thus option $A$ is correct.

Note: Maltase enzyme is used to break down maltose to glucose. This occurs as the hydrolysis of the glycosidic bond happens in the presence of maltase enzyme. Maltose can easily be detected by the Woehlk test or Fearon's test on methylamine. Maltose is sweet but only $30 - 60\%$ as the sugar. Maltose can be obtained by allowing grain to soften in water.