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.

diagram of lipid bilayer structure with extracellular environment (outside the cell), phospholipid, head, tails, intracellular environment (inside the cell)

select the true statements.

• the cell membrane is made of two layers of phospholipids.
• phospholipid heads touch the extracellular environment.
• phospholipid tails touch the cytoplasm inside the cell.
• phospholipid heads touch the intracellular environment.

Explanation:

1. For "The cell membrane is made of two layers of phospholipids": The text says the cell membrane is a lipid bilayer made of phospholipids, so two layers (bilayer) of phospholipids form it. This is true.
2. For "Phospholipid heads touch the extracellular environment": From the diagram and text, the top layer (extracellular side) has phospholipid heads facing out, so heads touch extracellular environment. True.
3. For "Phospholipid tails touch the cytoplasm inside the cell": The tails are between the two layers of heads. The intracellular environment (cytoplasm is inside) has the bottom layer of heads, and tails are in the middle, not touching cytoplasm. This is false (original check might be incorrect, but based on structure: tails are hydrophobic, heads are hydrophilic. So heads face water - based environments (extracellular and intracellular), tails face each other. So tails do not touch cytoplasm (intracellular water - based), so this statement is false. Wait, but maybe the original check was wrong. Wait, let's re - check. The intracellular environment is inside the cell (cytoplasm). The phospholipid tails are in the middle of the bilayer. The heads face the extracellular (top) and intracellular (bottom, cytoplasm) environments. So tails are between the two layers of heads, so tails do not touch cytoplasm. So this statement is false. But the original has a check. Maybe a mistake. However, following the text: "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." And the diagram: top heads face extracellular, bottom heads face intracellular (cytoplasm), tails are in between. So "Phospholipid tails touch the cytoplasm inside the cell" is false. But maybe the question's original check is wrong. But according to the content, let's analyze each:

Wait, maybe I misread. Let's do each:

1. "The cell membrane is made of two layers of phospholipids": True (bilayer = two layers of phospholipids).
2. "Phospholipid heads touch the extracellular environment": True (top layer heads face extracellular).
3. "Phospholipid tails touch the cytoplasm inside the cell": False (tails are between the two head layers, cytoplasm is water - based, tails are non - polar, so they avoid water, so tails do not touch cytoplasm).
4. "Phospholipid heads touch the intracellular environment": True (bottom layer heads face intracellular (cytoplasm) environment).

But the original has checks on all, but maybe that's a mistake. But according to the content, the true statements are:

• The cell membrane is made of two layers of phospholipids (because it's a lipid bilayer of phospholipids).
• Phospholipid heads touch the extracellular environment (top layer heads face outside).
• Phospholipid heads touch the intracellular environment (bottom layer heads face inside, cytoplasm is inside).

The statement "Phospholipid tails touch the cytoplasm inside the cell" is false because tails are hydrophobic and face each other, not the water - based cytoplasm.

But maybe the question's options have some errors, but based on the text and diagram:

True statements:

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

The third statement is false.

But the original image has checks on all, which might be an error. However, to answer based on the content:

Answer:

The true statements are:

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

(Note: The statement "Phospholipid tails touch the cytoplasm inside the cell" is false as phospholipid tails are hydrophobic and are oriented towards each other in the interior of the lipid bilayer, while the hydrophilic heads face the aqueous extracellular and intracellular (cytoplasm - containing) environments.)