This is a direct question from NCERT Class 12 Biology (Chapter: Biotechnology and Its Applications). Proteases (enzymes that break down proteins) and nucleases (enzymes that break down nucleic acids) are NOT present in blood plasma. Proteases are found in the digestive tract where they help digest food proteins. Nucleases are present inside cells. This is significant because protein-based pharmaceuticals (like insulin) can be injected into the bloodstream and remain functional since these degrading enzymes are absent. This concept is related to Question 13 in the context about orally active protein pharmaceuticals - the major problem encountered is that if taken orally, these proteins would be degraded by proteases in the digestive system, which is why they must be injected instead.