BIOL 1107 In each of the two tests (starch and sugar)

12 Jun BIOL 1107 In each of the two tests (starch and sugar)

Question
Biological Macromolecules
Hands-On Labs, Inc.
Version 42-0291-00-02

Lab Report Assistant
This document is not meant to be a substitute for a formal laboratory report. The Lab Report
Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data
tables that should be addressed in a formal lab report. The intent is to facilitate students’
writing of lab reports by providing this information in an editable file which can be sent to an
instructor.

Exercise 1: Starch and Sugar
Data Table 1. Benedict’s Reagent Data.
Sample

Initial Color

Final Color

Reducing Sugar Present
in Sample? Y or N

Final Color

Starch Present in Sample?
Y or N

dH2O
Albumin
Unknown
Milk
Glucose

Data Table 2. Lugol’s Iodine Data.
Sample

Initial Color

dH2O
Albumin

1

Unknown
Milk
Starch
Raw Potato

Questions
A. In each of the two tests (starch and sugar) a positive and negative control was used. What
was the positive control in each of the tests and what was the negative control. Explain
your answers.
B. Did the Benedict’s test for reducing sugars net a positive or negative result for milk?
Research the sugar content of milk and the definition of a reducing sugar to explain if your
result is what you would expect.
C. Based on your results, is sugar and/or starch present in your Unknown? Use your results to
explain your answer.

Exercise 2: Proteins and Lipids
Data Table 3. Biuret’s Reagent Data.
Sample

Initial Color

Intermediate Color

Final Color

Protein Present
in Sample? Y or
N

dH2O

Clear

Light blue

Light blue

No

Albumin

Mainly cloudly;
a little clear

Light Purple

Light purple

Yes

2

Unknow
n

Slightly cloudy; a
little clear

Purple

Purple

Yes

Milk

A clear white

Purple

Purple

Yes

Data Table 4. Lipid Observations.
Sample

Sample Observations

Lipid Present in
Sample? Y or N

Distilled water

Red on the pencil

No

Albumin

Red on a pencil

No

Unknown

Not a lot of red on the pencil

Not much

Milk

Not a lot of red on the pencil

Not much

Vegetable oil

Red on a pencil

Yes

Questions
A. Review the Data Tables in Exercises 1 and 2. Compare the results of the Unknown for all
tests to the results for the various known samples to determine the identity of the
Unknown. Explain the identity of the Unknown using your experiment results in the
exercises to help explain and support your answer.
B. Eggs are known to contain cholesterol which is a lipid. Did your experiment results indicate
a presence of lipids in the albumin solution? Think about this result and where cholesterol
is present in eggs to explain how your results support or reject cholesterol in eggs. How
could you test this? Explain the experiment that you would perform to test this.
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