Response The weight differences support the hypothesis because the solution

Response the weight differences support the

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Response: The weight differences support the hypothesis because the solution that had relatively similar sucrose concentration level to the one in the beaker 1 had a minor weight change. Also, both hypotonic and hypertonic solutions in the dialysis showed weight changes. Therefore, I believe the hypothesis and prediction were supported by the experiment result. 5. From your results, which of your “unknown” solutions appears to contain more sugar (among other unknown solutes)? Response: The first solution seems isotonic whereas the second solution contains more sugar. Therefore, the second solution appears to contain more sugar than the first solution. 6. Do your “unknown” sugar solutions contain more or less sugar (among other unknown solutes) than the 3%, 15% and 30% sucrose solutions? Why? Response: The first solution contains about 15% sucrose solution because there was very small weight change occurred. In contrast, the second solution contains about 3%. 7. What characteristics of your “unknown” solutions besides sugar content might impact the amount of swelling (or lack of swelling) in your dialysis bags containing these solutions? How might this impact your conclusions about the amount of sugar present in your “unknown”? Response: Besides the concentration of sugar in a solvent, I think the level of concentration of sugar in the beaker or the environment will impact the amount of swelling or lack of welling in the dialysis bags. If the concentration has relatively lower level of sugar concentration then all the dialysis bags, then it will shirk all the bags. 8. Cells exchange many substances with their environments using simple diffusion through the lipid bilayer. Describe properties of the lipid bilayer and what properties block simple diffusion (via passive transport). Why is simple diffusion through the lipid bilayer not sufficient for all substances? Provide examples of two such substances. Response: Simple diffusion through the cell membrane is not sufficient because the membrane is designed to be selectively permeable. The non-polar hydrophobic molecules would be repelled. Also, the concentration and electronic gradients exist within the cell. Therefore, energy is required to transport large or ion molecules. For example, the sodium- potassium pump uses ATP to move sodium and potassium ions against the concentration gradient through the cell membrane. 9. A concentration gradient affects the direction that solutes diffuse. Briefly describe how molecules diffuse with respect to concentration.
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BI205: Introductory Biology II Week 4 Lab Page 9 of 9 Response: diffusion is a process where molecules are moved from higher concentration region to lower concentration region according to the concentration gradient rule. 10. What family of proteins facilitates the movement of water across the cell plasma membrane? Briefly describe the structure of these proteins, and relate this structure to their function. Response: Aquaporins are integral membrane proteins that form pores in the cell membrane. It appears to be channels which are small enough to prevent molecules larger than water molecule from passing.
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  • Spring '17
  • Andrew Bouwma
  • Osmosis, Introductory Biology II

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