$ELISA$ method works on which of the following principles?

In which year did the company Eli Lilly prepare two $DNA$ sequences corresponding to $A$ and $B$ chains of human insulin?

The two polypeptide chains of human insulin are linked together by which of the following?

Consider the following statements about therapeutic drugs:
$I$. The recombinant $DNA$ technology is used for the production of therapeutic drugs which are safe and effective.
$II$. It avoids unwanted immunological responses,commonly observed with similar products isolated from non-human sources.
$III$. About $30$ recombinant therapeutics have been approved for human use in the world,including India.
Which of the statements given above are correct?

What is gene therapy? Illustrate using the example of adenosine deaminase $(ADA)$ deficiency.

Which protein production was successfully introduced in $E. coli$?