Which of the following statements correctly completes the sentence: 'Biofilms are not _________.'?

• A. capable of forming on both living and non-living surfaces
• B. protected by an extracellular polymeric substance (EPS) matrix
• C. structured communities of microorganisms
• D. composed of a single type of microorganism

Answer: (D)

Verified step by step guidance

1. Understand the definition of a biofilm: Biofilms are structured communities of microorganisms that adhere to surfaces and are embedded within a self-produced matrix called extracellular polymeric substance (EPS).
2. Analyze each option in the context of biofilm characteristics: Biofilms can form on both living and non-living surfaces, so the first statement is true and does not complete the sentence correctly.
3. Recognize that biofilms are protected by an EPS matrix, which provides structural stability and protection, so the second statement is also true and does not complete the sentence correctly.
4. Note that biofilms are indeed structured communities of microorganisms, meaning the third statement is true and does not complete the sentence correctly.
5. Identify that biofilms are typically composed of multiple types of microorganisms, not just a single type, so the statement 'Biofilms are not composed of a single type of microorganism' correctly completes the sentence.