Pre-lab questions:

Published: 2020-10-12 12:00:34
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Pizza is mostly made from cheese, bread and tomatoes thus the macromolecules that may be found in pizza are carbohydrates from wheat used to make bread, proteins from the cheese and lipids probably from the oils. Bread is mainly made from grains such as wheat which are major sources of starch thus the macromolecules that may be present in bread would be carbohydrates and may be a little protein. Peanut butter is prepared from peanuts that are actually legumes so the macromolecules that I presume to be contained in peanuts would be proteins, a little carbohydrates and lipids from fats. I would presume the macromolecules found in eggs are proteins because they contain all the essential 9 amino acids.

A chemical indicator is a substance that gives a visible sign either by changing color, of the absence or presence of a verge concentration of a chemical type for example an alkali or an acid in a solution.

If starch is present, then adding iodine will turn the solution purple.

If the protein is present, then adding copper sulfate and sodium hydroxide will turn the solution black.

If lipids are present, adding Sudan III will turn the solution a bright red.

The control group incase we are testing for the presence of macromolecules would be water.

The variable that is independent in the test would be absence or presence of macromolecules.

The dependent variable would be color change.

Lab questions

Phase 1: Test for starch:


What color did the starch Control (water) turn? Yellowish-brown Color of iodine solution is retained thus absence of starch

What color did the Test for starch turn? Dark purple There is presence of starch because of the color change.

Phase 2: Test for proteins:

Protein Color Why?

Color of the control water Blue It retains the color of copper sulfate(blue) due to the absence of the peptide bonds thus there is absence of proteins

Color for test of protein Black The copper atom reacts with the peptide bond to change the color from blue to black thus there is presence of proteins.

Phase 3: Test for lipids

Lipid Color Why?

Color of the control water A red layer at the top of water Sudan III is insoluble in water and less dense than water thus the Sudan III forms red layer above the water. This shows there is absence of lipids

Color for test for lipid It turns bright red The oil will stain the Sudan III red since it contains triglycerides thus there is presence of lipids.

Phase 4: Test for unknown

Unknown Test tube Color Molecules present

Test tube that showed a completely positive response to an indicator solution Unknown starch Purple Starch



Unknown protein Black Unknown lipid Bright red Phase 5: Test for Milk

Milk Test tube Color Molecules present

Test tube that showed a completely positive response to an indicator solution Milk starch Yellowish-brown Proteins and lipids are the present macromolecules.

Milk protein Black Milk lipid Bright red Post lab questions

The control groups (water) do not contain any of the macromolecules (starch, protein, and lipid).

Control groups are used to give untouched examples of what the substance was before one tampered with it thus the two can be compared for any changes. Therefore water is used because it is purified and contains no macromolecules.

Pizza test tube Color of the solution

Starch Purple

Protein Black

lipid Bright red.


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