Q.How was Insulin obtained before the advent of rDNA technology? What were the problems encountered?

Step 1. State the pre-recombinant source: in the early years, insulin used to treat diabetic patients was isolated and purified from the pancreases of pigs and cows (slaughterhouse by-product), since a large-scale source of human insulin did not exist. Step 2. State the core problem: although animal insulin is structurally very similar to human insulin, the small differences between them meant it was recognised as foreign by some patients' immune systems, resulting in allergic reactions in some diabetics who used it long-term. Step 3. Note the broader practical limitations this implies, even though not spelled out as a separate list in the text — dependence on animal pancreas supply also constrained how much insulin could be produced and at what consistency, which is exactly the gap recombin …

State the pre-rDNA animal-pancreas source and the specific allergic-reaction pr …

• Failing to name the specific problem (allergic reactions from structural differences) and giving only a vague 'it was less effective' answer. …