Question

A student is given a small amount of unknown tan-colored liquid substance. This unknown liquid is placed into a glass of water and mixed. Despite mixing, the tan liquid remains separated from the water and collects as a large droplet at the top. Which of the macromolecule groups is this liquid MOST likely to be a member of? Select one of the following choices: nucleic acids. proteins. lipids. carbohydrates

Answer 1

lipids

Carbohydrates and nucleic acids are extremely polar due to the large number of oxygen atoms in these organic molecules. Polar organic molecules are able to form hydrogen bonds with the polar water molecules, allowing them to dissolve easily in water.

In contrast, lipids have very little oxygen, and are mainly nonpolar. Also, lipids are less dense than water. Due to these two characteristics, the lipids form a layer above the water in the mixture.

Answer 2

This liquid substance most probably be a member of the group of lipids. Liquids which do not dissolve in water are called hydrophobic substances. Nonpolar substances exhibit this effect. Lipids are a class of large molecules or macromolecules which are hydrophobic. Lipids include cholesterol, fat, and phospholipids.