Question

question 21 of 50
which molecules prevent cell membranes from dissolving in water?
a. polar phosphate groups
b. adenosine triphosphates
c. large globular proteins
d. nonpolar fatty acids

Explanation:

Cell membranes are made of phospholipids. Phospholipids have a polar phosphate head and non - polar fatty acid tails. Water is a polar molecule. According to the "like dissolves like" principle, polar molecules dissolve polar molecules and non - polar molecules dissolve non - polar molecules. The non - polar fatty acid tails of phospholipids prevent the cell membrane (which is made of phospholipids) from dissolving in water (a polar solvent). Polar phosphate groups (A) are hydrophilic (water - loving) and would interact with water. Adenosine triphosphates (B) are energy - carrying molecules and not directly related to preventing membrane dissolution. Large globular proteins (C) are part of the membrane but their main function is not preventing dissolution; it is the non - polar fatty acid part of phospholipids that plays the key role in preventing dissolution.

Answer:

D. Nonpolar fatty acids