AP Biology Questions on Endocytosis and Cell Transport

📚 Quick Study Guide

• 🧬 Cell Membrane: Acts as a selective barrier, regulating the passage of substances in and out of the cell.
• 🚀 Passive Transport: Requires no energy input from the cell (e.g., diffusion, osmosis, facilitated diffusion).
• ⚡️ Active Transport: Requires energy (ATP) to move substances against their concentration gradients.
• 📦 Endocytosis: Process by which cells engulf substances from their surroundings by forming vesicles.
  • 🍎 Phagocytosis: "Cellular eating" - engulfing large particles or cells.
  • 💧 Pinocytosis: "Cellular drinking" - engulfing extracellular fluid.
  • 🔑 Receptor-mediated Endocytosis: Highly specific process using receptor proteins to bind to specific molecules.
• 🚪 Exocytosis: Process by which cells release substances to the extracellular environment through the fusion of vesicles with the plasma membrane.
• ⚖️ Osmosis: The movement of water across a semipermeable membrane from an area of high water concentration to an area of low water concentration.
• 🌊 Tonicity: The ability of a surrounding solution to cause a cell to gain or lose water.
  • Isotonic: No net water movement.
  • Hypotonic: Water enters the cell (cell swells).
  • Hypertonic: Water leaves the cell (cell shrinks).

🧪 Practice Quiz

1. Which of the following is an example of active transport?
   1. Simple diffusion of oxygen across the cell membrane.
   2. Facilitated diffusion of glucose through a channel protein.
   3. The movement of sodium ions ($Na^+$) against their concentration gradient.
   4. Osmosis of water across a semi-permeable membrane.
2. What type of endocytosis is primarily involved in the non-selective uptake of extracellular fluid?
   1. Phagocytosis
   2. Pinocytosis
   3. Receptor-mediated endocytosis
   4. Exocytosis
3. A cell is placed in a hypertonic solution. What will happen to the cell?
   1. The cell will swell and possibly burst.
   2. The cell will shrink.
   3. There will be no change in the cell's volume.
   4. The cell will maintain a constant turgor pressure.
4. Which of the following processes involves the movement of substances from inside the cell to the extracellular fluid?
   1. Endocytosis
   2. Exocytosis
   3. Osmosis
   4. Diffusion
5. Receptor-mediated endocytosis is characterized by:
   1. The engulfment of large, undissolved particles.
   2. The non-specific uptake of extracellular fluid.
   3. The use of specific receptor proteins to bind to target molecules.
   4. The transport of water across a membrane.
6. Which transport mechanism is responsible for maintaining the high potassium ($K^+$) concentration inside animal cells?
   1. Simple diffusion
   2. Facilitated diffusion
   3. Active transport
   4. Osmosis
7. What is the primary role of vesicles in cellular transport?
   1. To provide energy for active transport.
   2. To maintain osmotic balance.
   3. To transport molecules within the cell or to the cell membrane for secretion.
   4. To facilitate the diffusion of small molecules.