Which of the following ARE characteristics of the horizontal laminar flow hood?

The horizontal laminar flow hood is designed primarily to provide a sterile work environment by directing filtered air in a unidirectional flow, creating a barrier against airborne contaminants. This flow protects the work area, tools, and cultures from contamination while also maintaining a controlled environment for handling sensitive biological materials.

This characteristic of safeguarding cultures against contaminants is critical in laboratory settings where maintaining sterility is essential for the integrity of experiments or cell cultures.

The other options do not accurately describe the functions or characteristics of a horizontal laminar flow hood. For example, although some hoods may influence air pressure, a horizontal laminar flow hood does not increase air pressure; it operates by maintaining a low-pressure air flow to prevent contamination. Refrigeration is not typically required for the functioning of these hoods, as their primary role is not temperature management but rather maintaining a clean air supply. Lastly, while horizontal laminar flow hoods support many types of materials, they are not limited to only transformed cell lines; they can be used for a variety of non-transformed and transformed biological samples.