Biology Lab

8 August 2016

Biology Lab 6 Please answer these questions then place them in the drop box for this lab. Use Microsoft word if possible. Lab 6: Diffusion 65 Questions 1. Which dye diffused the fastest in corn syrup? Red Dye In your chosen material? Lemon Concentrate, Blue Dye 2. Does the rate of diffusion correspond with the molecular weight of the dye? The the density of the medium and the molecular weight of the dye will determine the rate of diffusion. 3. Does the rate of diffusion change over time?

How might this affect your calculated diffusion rate compared to the actual diffusion rate? Yes, because the rate of diffusion is faster until the equilibrium is reached; after equilibrium the rate of diffusion begins to decrease. 4. Cells receive vital nutrients and rid toxic waste with the help of the circulatory system. What is the critical distance a cell must maintain from a capillary (the point of nutrient/waste exchange) in order to survive? Explain the role diffusion plays in this process.

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The cell has to maintain a distance of 40 to 200 micrometers. The diffusion maintains the concentration gradient that’s required by the cell in order to complete the process. 5. Describe why the medium the dyes diffuse through can affect the rate of diffusion. How does this relate to nutrient transport into cells? The rate of diffusion is affected by the characteristics of the medium such as the temperature and the density. The dye might be restricted in its movements and take longer to diffuse, but that depends on the characteristics of the medium.

This also relates to the nutrient transportation into the cells in the type of cell and structure. It also depends on the cell because different cells contain different properties and/or characteristics, so it may take shorter or longer when comparing different types of these cells. Questions 1. Which substance crossed the dialysis membrane? What evidence from your results proves this? The glucose crossed the dialysis membrane. The glucose test strip had changed colors which indicated there was a presence of glucose in the beaker.

What molecules remained inside of the dialysis bag? The starch had remained inside of the dialysis bag. 3. Of the substances that diffused through the bag, did all of the molecules diffuse out? About half of the glucose did diffuse through the bag. 4. Does the dialysis bag or the beaker contain more starch? What about glucose? The dialysis bag does contain more of the glucose and starch than the beaker does. 5. Is the bag hypotonic with regards to the Lugol’s solution, or the beaker? What about the starch solution?

Lugol’s: beaker and the starch; bag 6. What results would you expect if the experiment started with glucose and Lugol’s Solution inside of the bag, and starch and water in the beaker? Why? The starch would stay in the beaker and the glucose and Lugol’s solution would be inside and outside of the bag. The glucose would then able to diffuse because the molecules are now small enough to pass through it. 7. Draw a diagram of this set up. Use arrows to depict the movement of each substance in the dialysis bag and the beaker.

What type of membrane does the dialysis tubing represent? Give an example of this type of membrane that can be found inside the body. Semipermeable membrane; an example of this type in the human body can be found in the kidney. The kidney doesn’t allow the protein molecules to pass through the membrane. 9. How does the glucose concentration affect diffusion rate? The glucose concentration affects the diffusion rate by allowing for more rapid initial diffusion.

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