how does the structure of the phospholipid bilayer help the membrane function as a selective barrier?\na the…

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

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

Answer

Brief Explanations:

  • Option A: The phospholipid bilayer does not contain DNA. DNA is mainly in the nucleus (in eukaryotes) or nucleoid (in prokaryotes).
  • Option B: Hydrophobic tails repel water. Also, the bilayer does not allow all molecules to pass. Small non - polar molecules can pass more easily, while large polar molecules and ions cannot pass freely.
  • Option C: Hydrophilic heads do not have a role in allowing only large proteins through. Proteins pass through channels or carriers (if they are transmembrane proteins) or by endocytosis/exocytosis.
  • Option D: The phospholipid bilayer has a structure with hydrophilic heads (exposed to the aqueous environment, both inside and outside the cell) and hydrophobic tails (in the middle). This arrangement prevents most substances (especially large polar substances and ions) from passing freely through the membrane, making it a selective barrier.

Answer:

D. The arrangement prevents most substances from passing freely