When it triggers an abnormal or vigorous immune responce, treating the antigen that would normally cause no threat as something harmful.
Answer:
Good oral health and diet
fruits. vegetables. lean sources of protein such as lean beef, skinless poultry and fish; dry beans, peas and other legumes. low-fat and fat-free dairy foods.
Explanation:
The ratio of 
indicates the purity of nucleic acid.For pure DNA it should lie between 1.8-2.0.Whereas for RNA it should be greater than 2.
This is calculated for DNA using the given values of absorbance-
= 2.71
As the value is greater than 2.0,it reflects the RNA contamination in the sample.
