Which method can be used to remedy the issue of cells settling in cultures?

Using shaking or stirring in cell cultures is an effective method to remedy the issue of cells settling. When cells are growing in a culture medium, especially in suspension cultures, they tend to sediment or settle at the bottom of the container due to gravity. This can lead to uneven distribution of cells, where some cells may receive less nutrients and oxygen.

By shaking or stirring the cultures, you create movement in the medium, which helps to keep the cells in suspension and ensures that they remain evenly distributed throughout the culture. This not only promotes better nutrient exchange but also helps in maintaining a consistent environment for cell growth. Additionally, this method can enhance gas exchange, which is vital for cellular respiration, further supporting healthier cell proliferation.

Other methods like freezing the cultures or leaving them undisturbed would not address the settling issue effectively, and increasing the temperature might stress the cells or alter growth conditions unfavorably. Therefore, shaking or stirring is a practical and widely used technique to maintain optimal growth conditions in cell cultures.