Answer:
1. skin forms a physical barrier against pathogens
2. lysozyme in saliva kills pathogens by ingestion
3. mucus is a pathogen trap
4. phagocyte kills pathogens by breaking down their cell walls
Step-by-step explanation:
1. Skin covers almost all around the body, protecting inner systems from being exposed to pathogens (bacteria). Also, skin is an unfavourable environment for pathogens.
2. lysozymes are organelles in saliva that ingest pathogens (by phagocytosis) and break them down
3. mucus lines the inside of the throat and trachea. With its sticky texture (and cilia), it is able to trap pathogens and move it up to the throat, where it can be swallowed and killed in the stomach by stomach acids.