Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

What is the function of a catalyst in an anaerobic jar?

1. Keeps excessive condensation from forming

2. Keeps toxic levels of carbon dioxide from building up

3. Only works properly when damp

4. Combines residual oxygen with hydrogen to form water

The correct answer is: Combines residual oxygen with hydrogen to form water

A catalyst in an anaerobic jar plays a crucial role in the maintenance of anaerobic conditions by facilitating the chemical reaction that removes oxygen from the system. When residual oxygen is present in the jar, the catalyst promotes the reaction between this oxygen and hydrogen gas to form water. This reaction effectively decreases the oxygen concentration, which is essential for creating an environment suitable for the growth of anaerobic bacteria. The other options describe functions that do not accurately define the role of a catalyst in this context. For example, while keeping excessive condensation from forming is important for maintaining a stable environment, it is not the primary function of a catalyst. Similarly, preventing toxic levels of carbon dioxide is not a function attributed to the catalyst; rather, anaerobic jars typically rely on other mechanisms, like chemical reactions and gas absorption techniques, to manage gas levels. Lastly, while damp environments can influence the general effectiveness of reactions, a catalyst does not specifically require dampness to function in the context of reducing oxygen levels in the anaerobic jar.