Question

phospholipids are another type of lipid. they are the building blocks of cell membranes. the model shows the chemical structure of a phospholipid.
select the true statements.

• phospholipids contain only carbon and hydrogen atoms.
• cell membranes contain phospholipids.
• phospholipids have carbon atoms arranged in two long chains.

Explanation:

1. For the statement "Phospholipids contain only carbon and hydrogen atoms": Looking at the chemical structure, phospholipids have atoms like oxygen (O), phosphorus (P), nitrogen (N) too (e.g., the phosphate group has P, O; the choline part has N). So this statement is false.
2. For "Cell membranes contain phospholipids": The text says "They are the building blocks of cell membranes", so this is true.
3. For "Phospholipids have carbon atoms arranged in two long chains": From the structure, we can see two long hydrocarbon chains (the fatty acid tails), so this is true. So the true statements are "Cell membranes contain phospholipids" and "Phospholipids have carbon atoms arranged in two long chains". The first statement is false as phospholipids have other atoms (O, P, N) besides C and H.

Answer:

The true statements are:

• Cell membranes contain phospholipids.
• Phospholipids have carbon atoms arranged in two long chains.

(The statement "Phospholipids contain only carbon and hydrogen atoms" is false as phospholipids also contain oxygen, phosphorus, and nitrogen atoms.)