Which pathogen typically requires living tissue for its survival?

The correct answer is that a virus typically requires living tissue for its survival. Viruses are unique among pathogens because they cannot replicate or carry out metabolic processes on their own. Instead, they need to infect a host cell and hijack the host's cellular machinery to reproduce. This dependence on living cells for their lifecycle distinguishes viruses from other pathogens like fungi, bacteria, and yeast, which can often survive independently or on non-living organic matter.

Although fungi, bacteria, and yeast can be associated with living organisms and may cause diseases in them, they do not exclusively rely on living tissue for their survival. For instance, fungi can grow on decaying organic matter, bacteria can thrive in various environments, including soil and water, and yeast can ferment carbohydrates outside of a living host. This fundamental difference in survival strategies is what makes viruses distinct in their requirement for living tissue.