Final answer:
Oral-fecal transmission is the mode of transmission represented by the entry of pathogenic microorganisms or their toxins through the oral cavity and gastrointestinal tract. It occurs when pathogens in feces from an infected host enter the mouth of a new human host, commonly through contaminated food or water.
Step-by-step explanation:
The mode of transmission represented by the entry of pathogenic microorganisms or their toxins through the oral cavity and gastrointestinal tract is oral-fecal transmission. This type of transmission occurs when pathogens in feces from an infected host enter the mouth of a new human host through contaminated food or water, or on contaminated fingers. This mode of transmission is commonly associated with diseases like cholera and various types of gastroenteritis.