number 3 and 5 In one of todays experiments we use beets Why

number 3 and 5

In one of today\'s experiments we use beets. Why not use white onions instead? In other words, what is the advantage of using beets? Think back to last week\'s lab using dialysis tubing. We will be using dialysis tubing again this week. How is a cell membrane similar to this dialysis tubing? In the experiments using dialysis tubing in a solution within a beaker, the main process that is taking place is osmosis. Why could we definitively say that this process is definitely not active transport?

Solution

Answer:

3. Since nothing have been mentioned about the experiment, it appears that the most probable experiment being referred to here is the investigation of the effect of temperatures on cell membranes and osmosis.

When a piece of fresh beetroot is left to stand in a beaker of cold distilled water, very little pigment is released from the beetroot. When, however, a similar piece is placed into a beaker of hot water, pigment release happens more quickly and the surrounding water soon becomes coloured red.

A possible explanation for these observations could be that the structure of the plasma membrane is affected by temperature. As temperature rises, the damage to the plasma membrane will result in an increase in the amount of pigment released from the beetroot cells through osmosis.

In case of white onions, there are no colored pigments that can be monitored to study the process of osmosis. So, beets are preferred over white onion for the experiment.

5. Dialysis Tubing is a type of semi or partially permeable membrane tubing made from regenerated cellulose or cellophane. It is used for diffusion, or more accurately osmosis. It allows the passage of small molecules but not larger ones.

For active transport to take place, specialized transport proteins are required to be present in the membrane to allow for the movement of molecules/ions against the concentration gradient. Dialysis tubings does not possess any transport proteins or carrier that can facilitate the process. Thus, in the experiments with dialysis tubing, active transport cannot take place.