Essay on Biology Lab 6

Certain substances are able to diffuse across plasma membranes under the right conditions through selective permeability. The selection of these certain substances allows for cells to maintain homeostasis, as these substances move from higher concentration to lower concentration. The purpose of this experiment is to see whether or not Lugol’s will be able to diffuse across dialysis tubing, which acts as a membrane. Lugol’s turns black when it interacts with starch, which will make the diffusion easy to see. This is all based off of a caterpillar eating a plant. The starch present in the leaves causes the caterpillar to produce amylase, which breaks down starch. In one experiment, the tubing will contain starch and amylase, while the other tubing

1.Discuss the structure of the plasma membrane and explain the process of active and passive transport through the membrane.

If the solution in the left beaker contained both urea and albumin, which membrane(s) could you choose to selectively remove the urea from the solution in the left beaker? How would you carry out this experiment?

In this lab experiment, we were testing diffusion across a plasma membrane using starch, amylase and Lugol's. The results from the experiment supported my hypothesis. The amylase did in fact digest the starch. The control in our experiment without the amylase confirmed this. In the original beaker, filled with 2/3 water and 4 pipettes of Lugol's, was a tied off plastic tubing (dialysis tubing) filled with starch and amylase. In the control beaker, filled with 2/3 water and 4

The dialysis bag experiment resulted with beaker one having relatively similar numbers, showing as an isotonic medium. Beaker two’s solution gradually increased within an hour which caused the product to

3. Explain your prediction for the effect Na+ Cl- might have on glucose transport. In other words, explain why you picked the choice that you did. How well did the results compare with your prediction?

7. Explain how incubation plant tissues in a series of dilutions of sucrose can give an

The dialysis tubing will be clamped at one end in order to fill it and then clamped at the other end to seal the filled bag. If the bag is not soft and floppy, the experiment will not work. Blot a bag with a paper towel to absorb the moisture and weigh it, if this blotting process is not done it could interfere with the weight readings creating inaccurate information. After the bags of the solutions are prepared, they will be placed into five different beakers with different solutions. Beakers 1-4 will be filled with tap water and the fifth beaker is filled with 40% sucrose and water. Fill each beaker with just enough water or solution so that the bag is covered and place the bags in the beakers simultaneously and record each time. Every 10 min the bags are to be taken out, blotted, and weighed again before returning them back into their respective beaker for another 10 min. The process is repeated until you have reached 90 min. The weights should be recorded in grams (g).

In this lab we found out that the dialysis bag contained more fluids inside it. This can happen because sucrose is small enough to pass through the selectively permeable membrane. Some errors that might have been encountered during the lab could have been the fact that some of the dialysis bags were not tightly tied with the dental floss, or that the wrong substance was used. Another possible source of error was if the carrot strips had been dehydrated from the beginning of the experiment or were already

Three peaks are observed in Figure 1 (concentration of glucose vs. elution volume) which was expected due to the results in table 4 that show intervals of elution. The intervals of the elution are represented as peaks on the graph. The intervals are due to the glucose molecules that enter the beads of the column causing the glucose molecules to elute slowly. Two peaks are observed in Figure 2 (concentration of starch vs. elution volume), which was not expected. One peak was expected for the

The hypothesis states that if the solution is hypotonic the results will decrease, if the solution is hypertonic the results will increase and if the solution is isotonic the solution will vary and or remain constant. In order to test the predictions of the hypotonic, hypertonic, and isotonic hypothesis for the solution  made during the study,  four samples of sucrose were taken and placed into two different beakers each containing a different concentration. Then dialysis tubing A was placed into beaker 1 with B, C, and D placed into beaker 2 for 45 minutes and weighted at 15 minute intervals. My finding in the study was that each of the four samples changed from their initial weight and for the most part accurately proved the hypothesis.

Which materials diffused from the left beaker to the right beaker? NaCl, Urea, and Glucose at MWCO 200

There were several steps completed to prepare for the experiment. Three dialysis tubes were filled with approximately the same volume of distilled water and then were tied shut. The initial mass (in grams) of the tubes was taken using a triple beam scale. I then filled three 500 mL beakers with 400 mL of water each and dissolved different masses of solute (table sugar) in each beaker in order to make 5%, 10%, and 20% solutions. The beakers were labeled accordingly, and then 20 g, 40 g, and 80 g (respectively) of table sugar was weighed out using a digital scale and placed into the corresponding beakers. The sugar was stirred in using a stirring rod until all of the solute was completely dissolved.

Do you think urea will diffuse through the 20 MWCO membrane? Your answer : c. No, not at all.

Diffusion is the spontaneous movement of particles from where they are more concentrated to where they are less concentrated. For this experiment, a 14 cm glass was filled with cold tap water. A drop of red food coloring was dropped in the cup. A stopwatch was used to measure the time it took for the food coloring to get to the bottom of the cup. The average diffusion rate was .78 cm a second. If a different color was used, I do not think it would have made a difference in the results. The mood of the person experimenting could possibly alter the results. For example, if a person is under stress, they may accidentally squeeze too much altering the rate of diffusion. If the water was warmer, this may have sped the