PSI Texas State Board Nail Tech practice exam

Which of the following is an example of a parasite?

1. Fungi

2. Bacteria

3. Viruses

4. Scabies

The correct answer is: Scabies

The identification of scabies as a parasite is based on its biological characteristics and behavior. Scabies is caused by the Sarcoptes scabiei mite, which is a tiny organism that lives on or in the skin of its host. This mite burrows into the skin, where it feeds on the host's skin cells, resulting in itching and discomfort. This relationship is a hallmark of parasitism, where the parasite benefits at the expense of the host. In contrast, the other options—fungi, bacteria, and viruses—can be grouped differently based on their classifications. Fungi are primarily saprophytic or can be parasitic, but they do not specifically fall under the definition of a parasite in the context typically associated with disease. Bacteria can be classified as beneficial, commensal, or pathogenic; however, they are not exclusively parasites like scabies. Viruses are obligate intracellular pathogens that rely entirely on host cells for replication and survival, but they do not have the typical traits associated with parasitic organisms, such as prolonged live-in behaviors seen with mites. Thus, scabies is appropriately categorized as a parasite due to its direct dependency on the host for survival and nourishment.