Diseases And Their Spread Quiz, Questions and Answers. 4th, 5th, 6th, grade science quiz online. Learn about bacteria and virus infections through a disease trivia question and answer MCQ online. Learn about some human diseases and how they are transmitted e.g. through sexual contact, saliva or other means. Learn about how contageous and infectious diseases are spread. Learn how to prevent the spread of diseases in this quiz. This is an online biology test for practice.