This answer key provides solutions for a typical cell transport worksheet, covering key concepts like diffusion, osmosis, active transport, and facilitated diffusion. Remember that specific questions on your worksheet might vary slightly, but the underlying principles remain consistent. This guide will not only provide answers but also explain the reasoning behind each, strengthening your understanding of cell transport mechanisms.
Note: Since I don't have access to your specific worksheet, I'll provide answers and explanations for common cell transport questions. Adapt these to your worksheet's specific questions.
Section 1: Diffusion and Osmosis
1. Define diffusion.
Answer: Diffusion is the passive movement of particles from an area of high concentration to an area of low concentration until equilibrium is reached. This movement doesn't require energy input.
2. Explain osmosis.
Answer: Osmosis is a specific type of diffusion involving the movement of water across a selectively permeable membrane from a region of high water concentration (low solute concentration) to a region of low water concentration (high solute concentration). The goal is to equalize the water concentration on both sides of the membrane.
3. What will happen to a red blood cell placed in:
* **a) Hypotonic solution:**
* **b) Hypertonic solution:**
* **c) Isotonic solution:**
Answer:
* **a) Hypotonic solution:** The red blood cell will swell and potentially lyse (burst) because water will move into the cell due to the higher water concentration outside the cell.
* **b) Hypertonic solution:** The red blood cell will shrink (crenate) as water moves out of the cell into the surrounding solution with a higher solute concentration.
* **c) Isotonic solution:** The red blood cell will remain unchanged as the water concentration is equal inside and outside the cell. There is no net movement of water.
4. Draw and label a diagram illustrating osmosis.
Answer: (This requires a drawing. The diagram should show a selectively permeable membrane separating two solutions with different water concentrations. Arrows should indicate the net movement of water from the area of high water concentration to the area of low water concentration.) Clearly label the hypotonic and hypertonic solutions and the direction of water movement.
Section 2: Active and Facilitated Transport
1. Define active transport.
Answer: Active transport is the movement of molecules across a cell membrane against their concentration gradient (from low concentration to high concentration). This process requires energy, typically in the form of ATP.
2. Explain facilitated diffusion.
Answer: Facilitated diffusion is the passive movement of molecules across the cell membrane with the help of transport proteins. Although it's passive (doesn't require energy), it still requires a protein channel or carrier to facilitate the movement of the molecule across the membrane. The movement is still from high to low concentration.
3. Give an example of each type of transport (active and facilitated).
Answer:
* **Active Transport:** The sodium-potassium pump in nerve cells, which moves sodium ions out of the cell and potassium ions into the cell against their concentration gradients.
* **Facilitated Diffusion:** The transport of glucose into cells using glucose transporter proteins.
4. How does active transport differ from passive transport?
Answer: Active transport requires energy (ATP) and moves molecules against their concentration gradient, while passive transport (diffusion, osmosis, facilitated diffusion) does not require energy and moves molecules down their concentration gradient.
Section 3: Application and Critical Thinking
(This section would contain application-based questions specific to your worksheet. Examples are below.)
1. How does the surface area to volume ratio affect cell transport efficiency?
Answer: A larger surface area to volume ratio increases the efficiency of cell transport because there is more membrane area available for transport processes relative to the volume that needs to be supplied. Smaller cells have a higher surface area to volume ratio and are more efficient at transport.
2. Explain the importance of cell transport in maintaining homeostasis.
Answer: Cell transport is crucial for maintaining homeostasis because it regulates the movement of substances into and out of cells, ensuring the internal environment of the cell remains stable despite changes in the external environment. This includes maintaining proper water balance, nutrient levels, and waste removal.
This expanded answer key provides a more comprehensive understanding of cell transport mechanisms. Remember to adapt this information to your specific worksheet questions. If you have specific questions from your worksheet, feel free to provide them, and I will do my best to help.
