Final answer:
True, biological matter such as serum, blood, or urine can decrease the effectiveness of germicides by interfering with their antimicrobial action.
Step-by-step explanation:
Biological matter such as serum, blood, or urine indeed lowers the effectiveness of a germicide. Organic materials present in these fluids can interfere with the chemical action of disinfectants and antiseptics, making them less effective at killing microorganisms.
This can require higher concentrations or longer exposure times for these germicidal agents to achieve their intended level of microbial control. Various factors influence the effectiveness of a germicide, including the presence of organic matter, the type of microorganisms present, the concentration and type of germicide used, temperature, and duration of exposure.