AP Bio Insta-Review Topic 2.5: Membrane Permeability

Overview

• Platform: Quizizz
• Created by: Tiffany Jones
• Target Audience: 9th - 12th Grade Biology Students
• Type: Quiz (18 questions)
• Category: Biology, Science
• Difficulty: Medium

Key Concepts

Membrane Structure

• Membranes are composed of phospholipids, which make them nonpolar.
• Structure includes a double layer of phospholipids with:
  • Phosphate heads associating with extracellular/intracellular regions
  • Fatty acid tails associating with the interior of the membrane

Membrane Permeability

• Nonpolar Molecules: Small, nonpolar molecules pass easily through the membrane.
• Polar and Charged Molecules: Have difficulty crossing without assistance.
• Water: Can pass through in small amounts, often through channel proteins called aquaporins.

Transport Mechanisms

• Transport Proteins: Allow small and polar substances to cross:
  • Channel proteins (e.g., aquaporins for water)
  • Carrier proteins

Specific Substances

• Easiest to Cross: Small, nonpolar molecules
  • Example: Carbon Dioxide (CO2)
• Difficult to Cross: Polar or charged substances
  • Examples: Glucose (polar), Sodium ions (Na+, charged)

Questions Breakdown

1. Small & Nonpolar: Easiest to cross due to membrane composition
2. Carbon Dioxide: Easily passes due to being small and nonpolar
3. Sodium Ions: Difficulty crossing due to being charged and polar
4. Water Passage: True that some water crosses unassisted
5. Transport Proteins: Assist in crossing membranes, specific to substance type
6. Cell Wall Presence: Identifies which organisms have cell walls (Fungi, Plants, Prokaryotes)

Important Terms

• Phospholipid Bilayer: Provides selective permeability
• Aquaporins: Channel proteins for water
• Selective Permeability: Allows some substances to cross more easily than others

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