Question

the semipermeable, or selectively permeable, cell membrane only allows certain substances to pass through it. the cell membrane is able to carry out this function because of its structure. the cell membrane is made of a lipid bilayer. the type of lipids that form the cell membrane are called phospholipids. phospholipids consist of a charged, polar head and two uncharged, nonpolar tails. this diagram shows the structure of the lipid bilayer. select the true statements. phospholipid tails touch the cytoplasm inside the cell. phospholipid heads touch the intracellular environment. phospholipid heads touch the extracellular environment. the cell membrane is made of two layers of phospholipids.

Explanation:

1. Analyze "Phospholipid tails touch the cytoplasm inside the cell": Phospholipid tails are non - polar and hydrophobic. The cytoplasm is an aqueous (polar) environment inside the cell. Hydrophobic tails avoid polar environments, so they do not touch the cytoplasm. So this statement is false.
2. Analyze "Phospholipid heads touch the intracellular environment": Phospholipid heads are polar and hydrophilic. The intracellular environment (cytoplasm) is aqueous (polar). So the polar heads of phospholipids in the inner layer of the lipid bilayer will interact with the intracellular (cytoplasmic) environment. This statement is true.
3. Analyze "Phospholipid heads touch the extracellular environment": Phospholipid heads are polar and hydrophilic. The extracellular environment is aqueous (polar). So the polar heads of phospholipids in the outer layer of the lipid bilayer will interact with the extracellular environment. This statement is true.
4. Analyze "The cell membrane is made of two layers of phospholipids": The cell membrane is a lipid bilayer, which means it is composed of two layers of phospholipids. This statement is true.

Answer:

• Phospholipid heads touch the intracellular environment.
• Phospholipid heads touch the extracellular environment.
• The cell membrane is made of two layers of phospholipids.