Find the correct statements from the following:
$I.$ Gene therapy is a genetic engineering technique used to treat diseases at the molecular level.
$II.$ Calcitonin is a medically useful recombinant product in the treatment of infertility.
$III.$ Bt toxin is a biodegradable insecticide obtained from $Bacillus \text{ } thuringiensis$.

$A$: Recombinant $DNA$ technology is less effective in therapeutic drug production.
$R$: Recombinant therapeutics induce unwanted immunological responses.

What is the demerit of using bovine insulin (from cow) and porcine insulin (from pig) in diabetic patients?

Some of the steps involved in the production of humulin are given below. Choose the correct sequence.
$(i)$ Synthesis of gene $(DNA)$ for human insulin artificially.
(ii) Culturing recombinant $E. coli$ in bioreactors.
(iii) Purification of humulin.
(iv) Insertion of human insulin gene into plasmid.
$(v)$ Introduction of recombinant plasmid into $E. coli$.
(vi) Extraction of recombinant gene product from $E. coli$.

Statements related to human insulin are given below. Which statement$(s)$ is/are correct about genetically engineered insulin?
$(a)$ Pro-hormone insulin contains an extra stretch of $C$-peptide.
$(b)$ $A$-peptide and $B$-peptide chains of insulin were produced separately in $E. coli$,extracted,and combined by creating disulfide bonds between them.
$(c)$ Insulin used for treating diabetes was extracted from cattle and pigs.
$(d)$ Pro-hormone insulin needs to be processed for converting into a mature and functional hormone.
$(e)$ Some patients develop allergic reactions to the foreign insulin.
Choose the most appropriate answer from the options given below:

How many of the following statements are correct?
$(i)$ Mature insulin is made up of $A, B$ and $C$ peptides.
$(ii)$ Removal of $C$-peptide helps in the maturation of insulin.
$(iii)$ In mature insulin,$C$-peptide is present.
$(iv)$ In insulin,chains $A$ and $B$ are linked by disulphide bonds.