A scientist used a light microscope to view images A and B of the same red onion epidermal cells in two solutions of different concentrations - Leaving Cert Biology - Question d - 2021

The cells in A maintain this shape due to turgor pressure. The vacuoles within the cells are filled with water, creating internal pressure against the cell wall. This pressure keeps the cells rigid and helps them maintain their structure, preventing wilting.

Solution B is more concentrated than solution A, meaning it has a higher solute concentration. As a result, the cells in solution B lose water to the surrounding solution, causing them to become plasmolyzed.

The process that has occurred to the cells in B is "Osmosis." This involves water moving from an area of high water concentration (inside the cell) to an area of low water concentration (the surrounding solution). The water moves through the selectively permeable membrane from the inside of the cell to the outside, leading to a decrease in cell turgor and causing the cells to shrink.

To restore the cells in B to the condition shown in A, they could be placed in a solution with a lower solute concentration. This would allow water to move back into the cells via osmosis, increasing turgor pressure and returning them to a turgid state.

Understanding the osmotic processes allows for better preservation techniques in food production. By controlling the concentration of solutions surrounding food, it is possible to minimize the growth of bacteria or fungi, thus extending the shelf life of food items. For instance, storing food in hypertonic solutions can draw out excess moisture, reducing spoilage.

A scientist uses a coverslip by lowering it slowly at an angle or lowering it with a needle to avoid introducing air bubbles into the specimen.

A coverslip is used to prevent the specimen from drying out or to protect the objective lens from contamination, as well as to hold the specimen in place during observation.