Lab 1: Carbohydrate Detection Tests

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What is the general composition of carbohydrates?

Carbon, hydrogen, and helium
Carbon, oxygen, and nitrogen
Carbon, oxygen, and hydrogen (correct)
Oxygen, hydrogen, and nitrogen

Which functional group is present in carbohydrates?

Ether functional group
Aldehydic or ketonic functional group (correct)
Carboxylic acid functional group
Amine functional group

What is the purpose of Molisch's Test?

To detect proteins in a solution
To detect nucleic acids in a solution
To detect carbohydrates in a solution (correct)
To detect lipids in a solution

What is the reaction underlying Molisch's Test?

Formation of Furfural and its derivatives (B) Signup and view all the answers

What is the purpose of Fehling's Test?

To detect the presence of reducing sugars and non-reducing sugars (B) Signup and view all the answers

Who developed the Fehling's Test?

H.C. Von Fehling (D) Signup and view all the answers

What is the typical colour of Fehling's A solution?

Blue (C) Signup and view all the answers

What is the role of tartrate tetra-anions in Fehling's solution?

Chelating agent (D) Signup and view all the answers

How are Fehling's A and B solutions mixed to prepare the final Fehling solution?

In equal volumes (B) Signup and view all the answers

What is the purpose of the control tube in the Fehling's test?

To contain distilled water (B) Signup and view all the answers

What is the expected outcome of the Fehling's test?

Formation of a red precipitate (A) Signup and view all the answers

In which condition are the tubes containing the sample and Fehling's solution placed?

In a water bath (B) Signup and view all the answers

What is the primary purpose of the Biuret test?

To demonstrate the presence of the peptide bond (A) Signup and view all the answers

What is the expected outcome of the Iodine test if starch is present?

A blue-black colored complex (B) Signup and view all the answers

What is the purpose of the control sample in the Iodine test?

To compare the results with the test sample (C) Signup and view all the answers

What is the initial step in the Biuret test procedure?

Add 2 cm3 of the liquid food sample to a clean, dry test tube (B) Signup and view all the answers

What is the effect of heating the test tubes in the Iodine test?

The color that develops in the test tubes disappears (B) Signup and view all the answers

What is the quantity of the liquid sample required for the Iodine test?

1 ml (A) Signup and view all the answers

What is the indicator of a positive Benedict's test?

Formation of a reddish brown precipitate (B) Signup and view all the answers

What is the purpose of heating the solution in a boiling water bath during Benedict's test?

To facilitate the reaction between the sample and Benedict's reagent (D) Signup and view all the answers

Which of the following sugars does not give a positive Benedict's test?

Sucrose (A) Signup and view all the answers

What is the function of CuSO4 in Benedict's test?

To act as an indicator for the presence of reducing sugars (C) Signup and view all the answers

What is the purpose of Barfoed's test?

To distinguish between monosaccharides and disaccharides (A) Signup and view all the answers

What happens to sucrose when it undergoes Barfoed's test?

It undergoes hydrolysis in the presence of an acid (D) Signup and view all the answers

What is the primary purpose of Barfoed's test?

To differentiate between monosaccharides and disaccharides (A) Signup and view all the answers

What is the role of the acidic medium in Barfoed's test?

It enhances the reduction of cupric ions to cuprous ions (C) Signup and view all the answers

What is the outcome of the test if red precipitates are formed after the initial 5 minutes?

The presence of a monosaccharide is indicated (C) Signup and view all the answers

Why is it necessary to allow the solution to cool gradually at room temperature?

To prevent the decomposition of the test solution (D) Signup and view all the answers

What happens to disaccharides when the heating period is increased?

They are converted to monosaccharides (D) Signup and view all the answers

What is the name of the test that is often used to detect the presence of protein in a given solution?

Biuret test (D) Signup and view all the answers