Graded Assignment

Lab Report: Investigating Biological Compounds

Answer the questions below. When you are finished, submit this assignment to your teacher by the due date for full credit.

Total score: __ of 25 points

Identifying Organic Compounds

(Score for Question: _ of 6 points)

Record the results of this lab in the following data table.

Answer:

Material Indicator: Iodine Indicator: Copper Sulfate and Sodium hydroxide Indicator Sudan III

Starch

Albumin

Vegetable oil

Unknown

Milk

Forming Conclusions

(Score for Question 1: _ of 9 points)

1. Which macromolecules were present in the unknown solution? In the milk?

Answer:

Type your answer here.

Identifying Parts of a Scientific Process

(Score for Question 2: _ of 5 points)

2. What was the role of the water test tube in each phase?

Answer:

Type your answer here.

Communicatin

For presence of starch in biological molecules, iodine test is used. Few drops of iodine solution are added to the sample (containing starch carbohydrate). If the color turns blue-black, it will indicate the presence of starch in the solution and vice versa.

Iodine test is commonly used for identification starch.

Sodium hydroxide/Copper sulfate test for detection of Albumin

This test is called as Biuret performed for the detection of proteins (Albumin in this case). In this experiment, Biuret reagent is used which is combination of copper sulfate and sodium hydroxide. Few ml of biuret reagent is added to the unknown sample for detection of albumin. A colour change from blue to violet or dark blue will indicate the presence of albumin (protein).

Sudan III Test for identification of lipids.

Sudan III is a dye used to give colour to non-polar substances. Sudan III test is used in general lab for detection of lipids in unknown solution. Sudan III is red brown in colour and will stain the oil red when comes in contact in a solution. It will form 2 layers, one will be oil with red layer and the other is water layer.

1. Which macromolecules were present in the unknown solution? In the milk?

As pure milk composed of Fat, carbohydrate’s and Proteins. So for detection of milk all tests are recommended.

Biuret test for detection of protein

Benedicts test for carbohydrates

Sudan III test for detection of fats.

So positive results for all above will indicate the presence of milk.

. 2.What was the role of the water test tube in each phase?

Water is used as a negative control in each step and will give negative results as compared to all the colour change results. Water role in all phases is its comparison with all the other unknown samples as we know that there are no macro molecules in water sample.