Question

how do phospholipids arrange themselves?
phospholipids arrange in two layers, called a ______________.

• the heads face ____________ (toward water).
• the tails face ____________ (away from water).

this arrangement creates a ____________ barrier that protects the cell.
why is the bilayer important?
the phospholipid bilayer:

• helps the cell keep its internal ____________ stable (homeostasis).
• allows some molecules to pass through but blocks others. this is called ______________.
• provides ____________ for the cell.

what can pass through the bilayer easily?

• small, non - polar molecules (like ______ and ______) can pass through easily.
• large or charged molecules (like ______ or ______) need help to cross.

Explanation:

• Phospholipids form a bilayer. The hydrophilic (water - loving) heads face outward (toward water), and the hydrophobic (water - fearing) tails face inward (away from water). This creates a selectively permeable barrier.
• The bilayer helps maintain internal environment (homeostasis), has selective permeability (allowing some molecules and blocking others), and provides protection.
• Small non - polar molecules like oxygen (\(O_2\)) and carbon dioxide (\(CO_2\)) pass easily. Large or charged molecules like glucose or ions (\(Na^+\), \(Cl^-\) etc.) need help.

Answer:

1. bilayer
2. outward (toward water)
3. inward (away from water)
4. selectively permeable
5. environment
6. selective permeability
7. protection
8. oxygen (\(O_2\))
9. carbon dioxide (\(CO_2\))
10. glucose
11. ions (e.g., \(Na^+\), \(Cl^-\))