0
Add your answer:
Earn +20 pts
What substrate gives a positive reaction for benedicts reagent?
Reduction of Benedict's reagent occurs with reducing sugars such as glucose, fructose, and galactose, giving a positive test result. This test is used to detect the presence of reducing sugars in various food products.
Will hydrolysed dextrine give positive response to Benedict test?
Yes, hydrolyzed dextrin will give a positive response to the Benedict test as it contains reducing sugars that can react with the Benedict's reagent to form a colored precipitate indicating the presence of reducing sugars.
Why fructose gives positive tollen reagent test?
Fructose is a reducing sugar due to the presence of a free ketone group. When fructose is exposed to Tollens reagent (ammoniacal silver nitrate), it undergoes oxidation, reducing the silver ions to metallic silver which forms a silver mirror on the walls of the test tube, giving a positive test result.
Will albumin give positive result to Benedict test?
No, albumin will not give a positive result to the Benedict test. The Benedict test is used to detect the presence of reducing sugars such as glucose, fructose, and maltose, not proteins like albumin.
Why does fructose give a positive Benedicts test?
Benedict's test detects the presense of the aldehyde group. Fructose is a ketose rather than an aldose, but it's converted to glucose or mannose (both of which are aldoses) by the base in Benedict's reagent. All monosaccharides give a positive Benedict's test because they're all either aldoses or alpha-hydroxy ketoses that get transformed into aldoses. Sucrose does not, because while it contains fructose and glucose, both of which do test postive, the saccharides in sucrose are "locked" into hemiacetal form and cannot undergo ring opening to expose an aldehyde group. (It's a very weak lock; dilute acid ... like, say, lemon juice ... will hydrolyse the saccharide linkage and allow the hemiacetal rings to open.)
Which of the following pairs give positive toollens test-hexanal,acetophenone and fructose,sucrose?
The simple sugars will not react with the test because they are not aldehydes.
Why sucrose does not give a positive Benedict's test but hydrolyzed sucrose does give a positive beneditcts test?
Sucrose does not contain a free aldehyde or ketone group needed to reduce Benedict's reagent, so it does not give a positive Benedict's test. When sucrose is hydrolyzed into glucose and fructose by acid or enzymes, the resulting glucose can then react with Benedict's reagent due to the presence of the free aldehyde group, producing a positive test result.
Do eggs test positive in benedicts test?
Yes, eggs can test positive in the Benedict's test because they contain glucose, which is a reducing sugar that reacts with the reagent in the test to form a colored precipitate.
Is fructose gives positive test with tollens reagent?
Fructose does not give a positive test with Tollens' reagent because it is a reducing sugar that does not have a free aldehyde group capable of reducing the Tollens' reagent. Tollens' reagent is typically used to detect the presence of aldehydes but may not react with fructose due to its ketone functional group.
After hydrolysis did sucrose give a positive test with fehlings test why orwhy not?
Sucrose would not give a positive test with Fehling's reagent after hydrolysis because sucrose is a non-reducing sugar. During hydrolysis, sucrose is broken down into its monosaccharide components (glucose and fructose), which are reducing sugars and can react with Fehling's reagent to give a positive test for reducing sugars.
Would sucrose test positive or negative with benedicts reagent?
No, surcose is a disaccharide without a hemiacetal group
Which is more sensitive test fehlings test or Benedicts test?
Benedict's test is more sensitive than Fehling's test for detecting reducing sugars in a sample. Benedict's reagent has a lower detection threshold and is known to give more accurate results compared to Fehling's reagent.
