Forensic Serology

Concept: In forensic biology, identifying biological fluids such as blood, semen, and saliva is important for criminal investigations. Various biochemical tests are used to detect these fluids based on specific enzymes or chemical reactions.
Step 1: Understanding semen detection in forensic science.
Semen contains a high concentration of the enzyme acid phosphatase, which originates from the prostate gland. This enzyme is commonly used as an indicator for the presence of semen in forensic samples.
Step 2: Identifying the appropriate test.
The Acid Phosphatase Test is used as a presumptive test for semen detection. When the reagent reacts with acid phosphatase, it produces a rapid color change, indicating the possible presence of semen. Thus, the correct answer is:

Concept: In forensic science, blood identification is usually carried out in two stages:

• Presumptive tests – These tests indicate the possible presence of blood.
• Confirmatory tests – These tests confirm that the stain is actually blood.

Presumptive tests are quick screening methods, while confirmatory tests provide reliable proof of blood in a forensic sample.
Step 1: Understanding presumptive blood tests.
Examples of presumptive tests include:

• Kastle–Meyer Test
• Benzidine Test
• Phenolphthalein Test

These tests react with the enzyme-like activity of hemoglobin and give a color change, suggesting the possible presence of blood.
Step 2: Identifying the confirmatory test for blood.
A confirmatory test is required to prove the presence of blood. One such test is the Takayama Crystal Test, which produces characteristic pink hemochromogen crystals when blood is present. This microscopic crystal formation confirms the presence of blood in the forensic sample. Thus, the correct answer is: