0
What else can I help you with?
What mixture of sugars gives positive results for all five tests?
A mixture of glucose, fructose, sucrose, and lactose typically yields positive results for all five common sugar tests: Benedict's test (for reducing sugars), Barfoed's test (for monosaccharides), Molisch's test (for all carbohydrates), Seliwanoff's test (to differentiate between aldoses and ketoses), and the iodine test (for starch). This combination includes both reducing and non-reducing sugars, ensuring a positive outcome across the different tests.
What were negative and positive controls in the Benedict's test?
In the Benedict's test, the positive control typically involves using a known reducing sugar, such as glucose, which should produce a color change indicating the presence of reducing sugars. The negative control usually consists of water or a non-reducing sugar solution, which should not show any color change, confirming that the test is working correctly. These controls help validate the accuracy of the test results by ensuring that any observed changes are due to the presence of reducing sugars in the test sample.
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.
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.
What is barfoed test?
The Barfoeds test will allow us to make a distinction between reducing monosaccharides and reducing disaccharides. If the Red tetrazolium test is done first and is positive for a reducing sugar, then the Barfoeds test will tell us if it is mono or di.
Why is the Benedict test not exclusive to glucose?
The Benedict test will return a positive value for any reducing sugar. It will work with fructose, for example. Benedict solution oxidizes all the reducing sugars such as glucose, galactose and fructose. This implies that a positive result of Benedict's test can be any of the reducing sugars, not necessarily glucose. It will oxidize the carbonyl (which present in all type of sugar classes). So if we get a positive result in the Benedict test, it is not necessarily glucose; it could be galactose or fructose that also a reducing sugar. So Benedict test can't be used to assure glucose.
Will Maltose produce a positive Benedict's test?
Yes, maltose will produce a positive Benedict's test because it is a reducing sugar. Benedict's reagent oxidizes the aldehyde or ketone group in reducing sugars, causing a color change from blue to orange/red in the presence of a reducing sugar like maltose.
Why doesn't aspartame react in Benedict's soluion?
It's not a reducing sugar. In fact, it's not a sugar at all. Benedict's solution gives a positive test, brick-red precipitate, with reducing sugars such as glucose and fructose.
Why does glycoproteins reacts positively with Molisch reagent?
Glycoproteins give positive results for Molisch's test. This answer is true because Molisch test was a test for sugar.
Will hydrolysed dextrine give positive response to Benedict test?
Yes, it should. Benedicts test will be positive for reducing sugars, and since glucose is such a sugar, and would be a product of dextrin hydrolysis, you should get a positive result with Benedicts reagent.
Why cant table sugar be the positive control in test using Benedict's solution?
Table sugar (sucrose) cannot be used as the positive control in a test using Benedict's solution because sucrose does not contain reducing sugars. Benedict's solution is used to test for the presence of reducing sugars, such as glucose and fructose, which can reduce the copper ions in the solution and cause a color change. Since sucrose does not have a free aldehyde or ketone group to reduce the copper ions, it will not produce a positive result in the Benedict's test. A positive control is typically a substance known to produce a positive result in the test, so using table sugar would not be appropriate in this case.
How is the coloured precipitate that is responsible for the positive test formed for reducing sugars?
The colored precipitate in the positive test for reducing sugars is formed due to the reaction between reducing sugars (such as glucose) and copper ions in Benedict's or Fehling's solution. The reducing sugar reduces the copper ions from their +2 state to +1, leading to the formation of a colored precipitate of copper(I) oxide.
