BIOLOGY (Basic) – Substance Exchange Across the Cell Membrane

Substance Exchange Across the Cell Membrane

Learning Time: 4-12 hours

Content: This topic covers the role and mechanisms of the cell membrane in substance exchange. Processes such as passive transport (diffusion, osmosis, facilitated diffusion) and active transport (pump systems, endocytosis, exocytosis) are explained in detail. The importance of selective permeability of the cell membrane and concentration gradients is emphasized. In the TYT, this topic is tested through problem-solving and concept questions related to substance exchange. Current curricula may also include the relationship of these processes to health (e.g., drug absorption) and the environment. Student learning about this topic is essential for understanding the mechanisms of cell survival.

• Passive Transport:
  • Simple Diffusion (Movement of Oxygen Molecules)
  • Filtration (Filtration in the Kidneys)
• Active Transport:
  • Pump Systems (Na+/K+ Pump, Ion Transport)
  • Endocytosis (Phagocytosis: Uptake of Bacteria)
  • Exocytosis (Hormone Release)
• Diffusion and Osmosis:
  • Concentration Gradient (Distribution of Sugar)
  • Isotonic, Hypotonic, Hypertonic Solutions (Red Blood Cell Swelling)
• Facilitated Diffusion:
  • Carrier Proteins (Glucose Transport)
  • Channel Proteins (Ion Channels)