Answer to Question 1
2
Change in bowel habits is one of the seven danger signals for cancer. Changes in bowel habits and blood in the stool are common signs of colorectal cancer. Vomiting, decreased appetite, or recent blood infection could be symptoms of other health problems, but they are not necessarily colorectal cancer.
Answer to Question 2
4
An immunogen is any molecule that elicits an immune response. An antigen is any molecule that can bind with a specific antibody. An antigen that does not elicit an immune response by itself is called a hapten. An epitope is the reaction portion of an antigen.