Question

Which one of the following is non-reducing carbohydrate?
a. Maltose
b. Sucrose
c. Lactose
d. Ribose 5 – phosphate

Answer 1

On-reducing sugar is a carbohydrate which is not oxidized by a weak oxidizing agent that is an oxidizing agent that oxidizes aldehydes but there is no alcohols, like the Tollen's reagent in a basic aqueous solution. The characteristic property of non-reducing sugars is that, in normal aqueous medium, they do not generate any type of compounds containing an aldehyde group. For instance: sucrose, which contains neither a hemiacetal group nor a hemiketal group, therefore, it is stable in water.

Complete answer:

Option A – Maltose
Maltose, also named as maltobiose or known as malt sugar, is a disaccharide created from two units of glucose joined with an α bond. In the isomer isomaltose are the two glucose molecules which are joined with an $\alpha$ bond. Maltose is considered as the two-unit member of the amylose homologous series, the main structural motif of starch

Option B – Sucrose
Sucrose is regular sugar. It is considered as disaccharide, a molecule composed of two monosaccharides: glucose as well as fructose. Sucrose is formed naturally in plants, from which table sugar is refined. It has the molecular formula- $C_{12}H_{22}O_{11}$.

Option C – Lactose
Lactose is also a disaccharide. It is a sugar composed of galactose as well as glucose subunits along with it has the molecular formula $C_{12}H_{22}O_{11}$. Lactose forms up around 2–8% of milk. The name Lactose comes from lac, the Latin word to describe milk, plus the suffix -ose used to refer to sugars.

Option D – Ribose 5 –phosphate.
Ribose 5-phosphate is both a product as well as an intermediate of the pentose phosphate pathway. The last step of the oxidative reactions in the pentose phosphate pathway is the Formation of ribulose 5-phosphate. Depending on the body's state, ribulose 5-phosphate can be reversibly isomerized to ribose 5-phosphate.

Hence, the correct answer is option (B).

Note: For human consumption, sucrose is extracted as well as refined from either sugarcane or sugar beet. Sugar mills are typically located in tropical regions where sugarcane is grown, crush the cane along with raw sugar which is shipped further to refine into pure sucrose.