Final answer:
A threshold dose-response curve shows a minimum dose needed for a response, while a non-threshold curve shows that any dose can cause a response.
Step-by-step explanation:
A threshold dose-response curve and a non-threshold dose-response curve are two types of curves used to represent the relationship between the dose of a substance and a biological response. The main difference between them lies in their shape and the way the response occurs.
A threshold dose-response curve shows that there is a minimum dose or level of exposure below which there is no detectable response. Once the threshold is reached, the response increases linearly with the dose. An example of a threshold dose-response curve is the relationship between the dose of a toxin and the occurrence of a specific symptom.
On the other hand, a non-threshold dose-response curve does not have a distinct threshold level. Instead, it shows that any amount of exposure to the substance can cause a response, but the severity of the response increases with the dose. An example of a non-threshold dose-response curve is the relationship between the dose of radiation and the likelihood of developing cancer.