From given statements select the incorrect statement. (a) Proteins which are obtained by recombinant DNA technology are called recombinant proteins (b) Downstream processing include separation and purification of the desired product (c) After purification the product has to be formulated with suitable preservatives (d) Downstream processing and quality control testing do not vary from product to product

Answer

To solve the question, we need to analyze each statement provided and determine which one is incorrect. Let's go through the statements one by one.

1. **Statement A**: "Proteins which are obtained by recombinant DNA technology are called recombinant proteins."
- This statement is true. Recombinant proteins are indeed proteins produced through recombinant DNA technology.

2. **Statement B**: "Downstream processing includes separation and purification of the desired product."
- This statement is also true. Downstream processing is a crucial part of bioprocessing that involves the separation and purification of the product after it has been produced.

3. **Statement C**: "After purification, the product has to be formulated with suitable preservatives."
- This statement is true as well. After the purification of a product, especially in pharmaceuticals, it is common practice to add preservatives to ensure the product's stability and shelf-life.

4. **Statement D**: "Downstream processing and quality control testing do not vary from product to product."
- This statement is incorrect. Downstream processing and quality control testing can vary significantly depending on the specific product being processed. Different products may require different methods of purification, separation, and quality testing.

Based on this analysis, the incorrect statement is **Statement D**.

### Summary of Steps:
1. Analyze Statement A: True.
2. Analyze Statement B: True.
3. Analyze Statement C: True.
4. Analyze Statement D: Incorrect.

### Final Answer:
The incorrect statement is **(d)** Downstream processing and quality control testing do not vary from product to product.