Question

how does the structure of the phospholipid bilayer help the membrane function as a selective barrier? a the dna in the bilayer blocks toxic molecules b the hydrophobic tails attract water, allowing all molecules to pass c the hydrophilic heads allow only large proteins through d the arrangement prevents most substances from passing freely

Explanation:

• Option A: DNA is not in the phospholipid bilayer. The bilayer is made of phospholipids.
• Option B: Hydrophobic tails repel water, not attract it. And not all molecules can pass.
• Option C: Hydrophilic heads do not allow only large proteins through. Small non - polar molecules can pass more easily.
• Option D: The phospholipid bilayer has a structure with hydrophilic heads (outer and inner surfaces) and hydrophobic tails (in the middle). This arrangement prevents most substances (especially large, polar, or charged ones) from passing freely, which is key for the membrane being a selective barrier.

Answer:

D. The arrangement prevents most substances from passing freely