Question

two layers of phospholipids make up the cell membrane. a single phospholipid is composed of one head and two tails. the two tails of the phospholipid face inward because
the tails are composed of phosphates and glycerol and position themselves away from polar substances.
the tails are composed of amino acids which are always hydrophobic.
the tails are composed of carbohydrates and therefore orientate themselves towards polar substances.
the tails are composed of fats and therefore orientate themselves away from polar substances.

Explanation:

1. Analyze each option:

• Option 1: Phospholipid tails are not made of phosphates and glycerol (the head has phosphate - glycerol). So this is wrong.
• Option 2: Amino acids are the building blocks of proteins, not phospholipid tails. So this is wrong.
• Option 3: Carbohydrates are not the components of phospholipid tails, and carbohydrates can be polar, but tails are non - polar. So this is wrong.
• Option 4: Phospholipid tails are made of fatty acid chains (fats), which are hydrophobic (non - polar). In the cell membrane, the aqueous (polar) environment is inside and outside the cell, so the non - polar tails face inward to avoid the polar substances. This is correct.

Answer:

the tails are composed of fats and therefore orientate themselves away from polar substances.