Practice question

Question

Radioimmuno assay (RIA) can be employed for the detection of insulin in blood plasma. For this, 125I labelled insulin is mixed and allowed to bind with a known concentration of anti-insulin antibody. A known volume of patients' blood plasma is then added to the conjugate and allowed to compete with the antigen binding sites of antibody. The bound antigen is then separated from unbound ones and the radioactivity of free antigen is then measured by gamma counter. Following are some of the statements made about this assay. (i) The ratio of radioactive count for unbound antigen to the bound one is more at the end of reaction. (ii) The ratio of radioactive count for unbound antigen to the bound one is less at the end of reaction. (iii) For a diabetic patient, the radioactive count for free antigen is less than that for a normal individual. (iv) For a diabetic patient, the radioactive count for free antigen is more than that for a normal individual. Which of the above statements are true?