Biochemical Lab Reagents: Functions and Tests Quiz

1. What do Benedict's Solution test for?

Test for Reducing Sugars like: Glucose or FructoseNegative: BluePositive: Ranges from Green to Reddish Orange

Test for presence of proteins in the solution.

Test for the presence of fats in the solution.

Test for the acidity of the solution.

Benedict's Solution is specifically used to test for reducing sugars like glucose or fructose by changing its color from blue to green to reddish-orange based on the presence and amount of the sugar.

Explanation

Benedict's Solution is specifically used to test for reducing sugars like glucose or fructose by changing its color from blue to green to reddish-orange based on the presence and amount of the sugar.

2. What is the test for Starch?

Benedict's

Biuret

Test for Starch (due to coil shape of starch)Negative: Yellowish BrownPositive: Blueish Black

Sudan IV

Iodine is used as a test for Starch due to the coil shape of starch molecules. It gives a positive result of blueish black coloration and a negative result of yellowish brown coloration.

Explanation

Iodine is used as a test for Starch due to the coil shape of starch molecules. It gives a positive result of blueish black coloration and a negative result of yellowish brown coloration.

3. What is the purpose of Sudan IV?

PH testing

Test for Lipid (reacts with Amino tail of chains)Negative: doesn't mix (powder)Positive: Red

Vitamin C detection

Blood type determination

Sudan IV is specifically used as a test for lipids by reacting with the amino tail of chains. It produces a red color when positive, and does not mix when negative, appearing as a powder.

Explanation

Sudan IV is specifically used as a test for lipids by reacting with the amino tail of chains. It produces a red color when positive, and does not mix when negative, appearing as a powder.

4. What is Biuret test used for?

Test for Lipids (Positive: Red color)

Test for Simple Sugars (Positive: Brick-red precipitate)

Test for Protein (Peptide Bonds of Protein chains)Negative: BluePositive: Pink to Violet

Test for Starch (Positive: Blue-black color)

The Biuret test is specifically used to test for the presence of proteins by detecting the peptide bonds in protein chains. The color change observed is from blue (negative result) to pink to violet (positive result).

Explanation

The Biuret test is specifically used to test for the presence of proteins by detecting the peptide bonds in protein chains. The color change observed is from blue (negative result) to pink to violet (positive result).

5. What is the role of Pepsin in the body?

Carbohydrate that helps in digestion of fats.

Protein that breaks down Proteins into smaller amino acid chains.

Vitamin that enhances calcium absorption.

Enzyme that synthesizes Proteins from amino acids.

Pepsin is an enzyme that is responsible for breaking down proteins into smaller amino acid chains in the stomach during digestion.

Explanation

Pepsin is an enzyme that is responsible for breaking down proteins into smaller amino acid chains in the stomach during digestion.

6. What is the function of Salivary Amylase?

Enzyme that breaks down Starch to Glucose

Enzyme that breaks down Protein to Amino Acids

Enzyme that breaks down Fats to Fatty Acids

Enzyme that breaks down Nucleic Acids to Nucleotides

Salivary amylase is responsible for initiating the digestion of carbohydrates by breaking down starch into simpler sugars like glucose.

Explanation

Salivary amylase is responsible for initiating the digestion of carbohydrates by breaking down starch into simpler sugars like glucose.

7. What does Disch diphenylamine test for?

Test for lipids

Test for carbohydrates

Test for DNA (the dioxyribose sugar)Negative: ClearPositive: Blue (intensity indicative of amount of DNA)

Test for protein

Disch diphenylamine is a chemical reaction that specifically detects DNA by producing a color change. When DNA is present, the solution turns blue based on the intensity of the color, indicating the amount of DNA. Therefore, options related to protein, carbohydrates, and lipids are not correct as they do not involve the Disch diphenylamine test for DNA.

Explanation

Disch diphenylamine is a chemical reaction that specifically detects DNA by producing a color change. When DNA is present, the solution turns blue based on the intensity of the color, indicating the amount of DNA. Therefore, options related to protein, carbohydrates, and lipids are not correct as they do not involve the Disch diphenylamine test for DNA.

8. Does the sample test positive or negative for Starch?

3. Negative for Starch

6. Negative for Starch

1. Negative for Starch

The correct answer is 2. A positive result for starch indicates the presence of starch in the sample being tested.

Explanation

The correct answer is 2. A positive result for starch indicates the presence of starch in the sample being tested.

9. What is the result when testing for the presence of starch?

3. Negative for Starch

2. Negative for Reducing Sugar

4. Positive for Reducing Sugar

The correct result for testing the presence of starch is a positive reaction, indicating the presence of starch molecules.

Explanation

The correct result for testing the presence of starch is a positive reaction, indicating the presence of starch molecules.

10. Biuret Test Tubes (for Proteins): Which one of the following substances will give a positive result for proteins?

2) Honey

1. Positive for Protein2. Negative for Protein3. Negative for Protein4. Negative for Protein (Neg. Control)5. Positive for Protein (Pos. Control)

3) Amino Acid Solution

4) Distilled Water

The Biuret test is a biochemical test used for detecting the presence of proteins. Egg Albumen, being a source of proteins, will give a positive result when subjected to the Biuret test.

Explanation

The Biuret test is a biochemical test used for detecting the presence of proteins. Egg Albumen, being a source of proteins, will give a positive result when subjected to the Biuret test.

11. Biuret Test Tubes (Protein Digestion by Pepsin)

Negative for Polypeptides

Positive for Lipids

Positive for Carbohydrates

In the Biuret Test Tubes, a negative result indicates the absence of protein or polypeptides. Option 2 is incorrect as a negative result does not indicate the presence of polypeptides. Option 3 and 4 are incorrect as they suggest positive results for carbohydrates and lipids, which are not detected by the Biuret test.

Explanation

In the Biuret Test Tubes, a negative result indicates the absence of protein or polypeptides. Option 2 is incorrect as a negative result does not indicate the presence of polypeptides. Option 3 and 4 are incorrect as they suggest positive results for carbohydrates and lipids, which are not detected by the Biuret test.

12. What are the results of Sudan IV Test Tubes on different samples?

5. No layers formed

4. Positive for Lipid

2. Positive for Lipid

3. Negative for Lipid

Sudan IV Test Tubes show layers of polar and non-polar liquids, which indicates the presence of lipids. Samples that are positive for lipids will show this layer formation, while samples negative for lipids will not exhibit this characteristic. Therefore, options 2 and 4 are incorrect as they suggest positive results for lipids, and option 3 is incorrect as it indicates a negative result for lipids, which should show the formation of layers. Option 5 is incorrect as it suggests no layers formed, which is not the expected outcome of the test.

Explanation

Sudan IV Test Tubes show layers of polar and non-polar liquids, which indicates the presence of lipids. Samples that are positive for lipids will show this layer formation, while samples negative for lipids will not exhibit this characteristic. Therefore, options 2 and 4 are incorrect as they suggest positive results for lipids, and option 3 is incorrect as it indicates a negative result for lipids, which should show the formation of layers. Option 5 is incorrect as it suggests no layers formed, which is not the expected outcome of the test.

13. What are the results of Dische Diphenylamine Tests Tubes with different solutions?

2. Positive for DNA (Incorrect quantity)

1. Negative for DNA (incorrect interpretation)

3. Positive for DNA (Contaminated sample)

The Dische Diphenylamine Tests Tubes should result in positive for DNA with large quantity, positive for DNA with lesser quantity, negative for DNA (in the case of contaminated sample, which should be interpreted as positive), and negative for DNA as a negative control.

Explanation

The Dische Diphenylamine Tests Tubes should result in positive for DNA with large quantity, positive for DNA with lesser quantity, negative for DNA (in the case of contaminated sample, which should be interpreted as positive), and negative for DNA as a negative control.