Question

extension questions

1. using the concepts of osmosis, explain why water is sprayed over produce in a grocery store. how might this change the appearance of the produce and why would this change be desirable?
2. suppose you made a lettuce salad in the afternoon, added salt and other seasonings, and then put the salad in the refrigerator. when you took the salad out of the refrigerator for dinner, the lettuce looked wilted and some water was in the bottom of the bowl. use the principles of osmosis to explain what happened.
3. in extreme cases, it is possible to die from drinking too much water. ingesting several liters of water in a short amount of time can lead to brain edema (swelling) and death. explain the effect of ingesting an extremely large amount of water at the level of the brain cells, including the role of osmosis in this process.
4. the diagram below shows a single - celled organism called paramecium, which lives in freshwater environments. this organism contains a specialized organelle called a contractile vacuole that helps maintain osmotic balance. predict how this organelle might help the organism survive given that it is constantly immersed in a hypotonic solution.

Explanation:

1. Osmosis is the movement of water across a semi - permeable membrane from an area of lower solute concentration to an area of higher solute concentration. When water is sprayed on produce, if the solute concentration inside the plant cells is higher, water will move into the cells by osmosis, making the produce appear fresher. If the water has contaminants, they could also enter the cells through osmosis and be detrimental.
2. In the salad, the salt and other seasonings create a hypertonic environment outside the lettuce cells. Through osmosis, water moves out of the lettuce cells into the surrounding environment, causing the lettuce to wilt. The water at the bottom of the bowl is the water that has left the lettuce cells.
3. When a large amount of water is ingested quickly, the extracellular fluid becomes hypotonic relative to the brain cells. Water moves into the brain cells by osmosis. This causes the cells to swell, leading to brain edema, which can be life - threatening as it can increase intracranial pressure and disrupt normal brain function.
4. Since the Paramecium is in a hypotonic solution, water will constantly enter the cell by osmosis. The contractile vacuole collects the excess water that enters the cell and periodically contracts to expel the water out of the cell, thus maintaining osmotic balance and preventing the cell from bursting due to excessive water intake.

Answer:

1. Osmosis can affect produce freshness and introduce contaminants.
2. Osmosis causes lettuce in a salad to wilt and water to accumulate in the bowl.
3. Ingesting too much water leads to osmotic water influx in brain cells causing edema.
4. The contractile vacuole expels excess water to maintain osmotic balance in Paramecium.