NURSING ANM AND GNM

NURSING EXAM QUESTIONS

BIOCHEMISTRY

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which of the following sugars will not test positive in Molisch’s test?
A
Triose
B
pentose
C
ketohexose
D
aldohexose
Explanation: 

Detailed explanation-1: -Although almost all carbohydrates and even some glycoproteins and nucleic acids can be detected in a substance by Molisch’s test, a few carbohydrates are exceptions. Such as tetrose and triose sugars don’t give Molisch’s test.

Detailed explanation-2: -Fructose is sugar so it will give a positive result for Molisch’s test and it is a monosaccharide, so it has a free ketone functional group, so it will have a positive result for Benedict’s test.

Detailed explanation-3: -The limitations of the Molisch Test can be given as follows. Due to the lack of the five carbon atoms required for furfural synthesis, trioses and tetroses do not yield a good result in this reaction. The Molisch test is not a carbohydrate-specific test.

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