Heterocyclic Chemistry & Natural Process - GATE Chemistry MCQ

Seliwanoff's test is a chemical test that distinguishes between aldose and ketose sugars. A mixture of concentrated HCl and resorcinol of 3ml is added to the sugar. Then the solution is boiled for a little time. If it is a ketose sugar like fructose and sucrose is the solution turns cherry red.  

Given, all the enzymes except pepsin cuts from the C-terminal side.

 
there are three π-bonds in pyridine ring. So, that total of 6π-electrons are invoved in delocalization. Hence, aromatic.

D-glucose, D-mannose and D-iodose all have aldehydic functional group and gives both positive tests.
While as D-fructose have ketonic functional group and gives negative bromine water test, but positive Tollen’s test.

 (mild nitrating agent) electrophilic addition on pyrrol takes place at second position then third  And Sn/HCI converts NO₂ to NH₂ group. 

It is a Reimer-Tiemann reaction and ring expansion is a major product in this reaction,

It is a solvent dependent reaction Br₂ in presence of alcoholic solvent gives diacetal but in absence of alcoholic solvent gives polybromination product.

Osazone of D-gulose and D-iodose.

Arg, His, and Lys are the basic amino acids