Question

select all of the following that are true of the phospholipid bilayer. check all that apply the fatty acid chains of the phospholipids make the middle section hydrophobic. the hydrophobic phosphate heads allow the membrane to be selectively permeable to nonpolar molecules. steroids embedded in the bilayer allow the membrane to remain fluid at various temperatures. glucose can easily diffuse through the membrane. the bilayer would function similarly if composed of triglycerides instead of phospholipids. some proteins embedded in the membrane help with transporting large molecules through the bilayer. plasmodesmata in plant cells and gap junctions in animal cells allow for direct exchange of material between adjacent cells.

Explanation:

1. Fatty acid chains (hydrophobic middle): Phospholipid fatty acid tails are nonpolar/hydrophobic, creating a hydrophobic core.
2. Hydrophobic phosphate heads: Phosphate heads are hydrophilic (not hydrophobic), so this is incorrect.
3. Steroids (membrane fluidity): Cholesterol (a steroid) maintains membrane fluidity across temperatures.
4. Glucose diffusion: Glucose is polar; it requires transport proteins (facilitated diffusion), so simple diffusion is not easy.
5. Triglycerides vs. phospholipids: Triglycerides lack a hydrophilic head, so they can’t form a bilayer with selective permeability.
6. Transport proteins: Embedded (integral) proteins facilitate transport of large/polar molecules.
7. Plasmodesmata/gap junctions: These structures directly connect adjacent cells for material exchange.

Answer:

• The fatty acid chains of the phospholipids make the middle section hydrophobic: ✔️
• The hydrophobic phosphate heads allow the membrane to be selectively permeable to nonpolar molecules: ❌ (Phosphate heads are hydrophilic)
• Steroids embedded in the bilayer allow the membrane to remain fluid at various temperatures: ✔️
• Glucose can easily diffuse through the membrane: ❌ (Glucose is polar, needs transport proteins)
• The bilayer would function similarly if composed of triglycerides instead of phospholipids: ❌ (Triglycerides are not amphipathic)
• Some proteins embedded in the membrane help with transporting large molecules through the bilayer: ✔️
• Plasmodesmata in plant cells and gap junctions in animal cells allow for direct exchange of material between adjacent cells: ✔️