Mississippi Valley State University
Department of Natural Sciences and Environmental Health
Joseph M Wahome PhD
BI 111 General biology lab 5;
Properties of Solutions and Test of Biological Molecules

Summary
Water is a universal solvent making up between 65% and 85% of living cells. Many of the chemicals found in living things and their surrounding environment are found in solution. The purpose of the lab exercise is examining the property of solutions. The second part of the lab involving techniques used to identify and differentiate molecules that constitute a large part of a cell’s metabolism.

A. Properties of solutions
Materials
i. Distilled Water ii. pH Paper iii. pH Meters iv. Milk
v. Vinegar vi. Fruit Juice vii. Bleach viii. Hydrochloric Acid ix. Soap Solution
x. Mouthwash xi. Denatured Alcohol xii. Antacid

Procedure

Test the pH of the materials listed above using both pH test paper and an electronic pH meter. Measure the pH of those solutions again after adding an antacid. What happens to the pH?

Solution pH Acid
Base
Mouthwash
4
Yes
No
Soap Solution
6
Yes
No
Vinegar
2
Yes
No
Distilled Water
5
Yes
No
Milk
6
Yes
No
Fruit Juice
4
Yes
No
Bleach
0
Yes
No
pH Paper
5
Yes
No

Test for Biological Molecules

Biological molecules are large molecules or macromolecules that constitute a large proportion of living cells. They are mostly made up of the elements: Carbon, hydrogen, oxygen, nitrogen and sometimes sulfur with small quantities of other elements included. It is important to be able to test for these molecules in materials that biologists handle routinely

Materials

i. Glucose ii. Sucrose iii. Starch iv. Albumin
v. Vegetable Oil vi. DNA vii. Distilled Water viii. Methylene Blue ix. Benedicts Solution
x. Iodine xi. Biurets Solution xii. Sudan IV Solution xiii. Brown Butcher Paper

1. STARCH
Pour one ml of starch suspension in a test tube and one ml of water in another test tube. Add 5 drops of iodine solution to each test tube. Shake well and record your observations.

2. SIMPLE SUGARS
Add one ml of glucose to a test tube and one ml of water in another test tube. Add two ml of Benedicts’ solution to each test tube. Heat in boiling water for 10 minutes and record your observations.

3. PROTEINS
Add one ml of Albumin to a test tube and one ml of water in another test tube. Add two ml of Biuret’s reagent to each test tube. Record your observations.

4. LIPIDS
Place a small drop of water and a small drop of oil separately on a brown paper. Record your observations

Chemical Testing to Identify an Unknown
Biochemical Test
Color
Unknown Result

Sample Control
(+/-)
Benedict’s Test(Reducing Sugars)
Glucose
Water
N/A
Iodine(Starch)
Starch Suspension
Water
After adding 5 drops of iodine to each test tube the water changed to a bright orange/yellowish color, but the starch