Biological Membranes: Practice Problems

Membrane Transport

Problem 1: Large Polar Molecule Transport

• Mechanism: Passive transport (no energy required).
• Likely Type: Facilitated diffusion (uses transport protein/channel).
• Answer: C (Facilitated diffusion)

Problem 2: Sodium-Potassium ATPase Inhibition

• Scenario: Poison (oben) interferes with sodium-potassium pump; cell lyses.
• Key Points:
  • Sodium-potassium pump moves 3 sodium out, 2 potassium in.
  • Inhibition increases sodium inside the cell.
  • Increased sodium causes water influx, cell swells, and lyses.
• Answer: C (Increases intracellular sodium)

Resting Membrane Potential

Problem 3: Factors Affecting Resting Membrane Potential

• Key Factors:
  1. Differential distribution of ions
  2. Active transport processes
  3. Selective permeability of phospholipid bilayer
• Answer: G (All three factors)

Problem 4: Function of Cell Membrane

• Question: Identify non-function of cell membrane.
• Non-Function: Protein synthesis (performed by ribosomes).
• Answer: B (Protein synthesis)

Problem 5: Dynamic Properties in Cell Membrane

• Most Rapid Movement:
  • Phospholipids moving within the plane of the membrane.
• Reason: Size and non-polarity ease the movement.
• Answer: A (Phospholipids within the plane)

Problem 6: Least Contribution to Membrane Fluidity

• Least Contributing Lipid: Trans glycerophosphate lipids (increase melting point, decrease fluidity).
• Answer: B (Trans glycerophosphate lipids)

Problem 7: Membrane Receptor

• Characteristics: Transmembrane, catalytic activity.
• Answer: D (Transmembrane protein with catalytic activity)

Cell Junctions and Diffusion

Problem 8: Non-Animal Cell Junction

• Non-Animal Junction: Plasmodesmata (found in plants).
• Answer: C (Plasmodesmata)

Problem 9: Diffusion and Osmosis

• Rely On: Electrochemical gradient of the specific compound of interest.
• Answer: A (Specific compound gradient)

Problem 10: Bulk Movement of Liquid into Cell

• Process: Pinocytosis
• Answer: B (Pinocytosis)

Resting Membrane Potential and Mitochondrial Membranes

Problem 11: Least Likely Resting Membrane Potential

• Leas Likely Value: 0 (wouldn't maintain gradients for activity).
• Answer: C (0 mV)

Problem 12: Inner vs Outer Mitochondrial Membrane

• Inner Membrane: Less permeable, lacks cholesterol.
• Answer: B (Less permeable and lacks cholesterol)

Final Remarks

• Comprehensive practice including various key concepts of biological membranes.
• Ensures understanding of both theoretical and practical aspects. Good luck!