Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow.
At the beginning of the 21st century, the rapid rise of multidrug-resistant bacteria, such as MDR-TB (Mycobacterium tuberculosis), has renewed interest in bacteriophages—viruses that infect and destroy specific bacterial species. Phage therapy involves using these natural viral predators to treat bacterial infections.
Phage therapy is highly specific; a particular phage will only target a specific strain of bacteria, leaving beneficial gut bacteria unharmed. However, bacteria can develop resistance to phages. One mechanism of resistance involves the mutation of bacterial surface receptors, preventing the virus from attaching. Another mechanism is the bacterial CRISPR-Cas system, which recognizes and cuts viral DNA.
When bacteriophages bind to a bacterium, they inject their genetic material, which uses the host's machinery to replicate. Eventually, the phages produce enzymes, such as endolysins, which digest the bacterial cell wall from within, causing the cell to lyse (burst) and release new phages to search for more hosts.
State what is meant by the term pathogen.
Name the type of pathogen that is targeted and destroyed by bacteriophages in phage therapy.
Suggest why bacteriophages used in patients must be purified to remove bacterial toxins and contaminants.
Based on the passage, why are bacteriophages chosen over broad-spectrum antibiotics to treat infections?
Suggest the name of a digestive enzyme that breaks down the proteins or amino acid linkages in bacterial cell walls.
Describe how the body's white blood cells, specifically phagocytes, destroy bacterial pathogens.
Use your knowledge of natural selection to explain how a population of bacteria can become resistant to bacteriophages.
