BIOD 171 Module 004 Notes | Anatomy & Physiology I Exam Prep 2026

BIOD 171 ESSENTIAL MICRO BIOLOGY

MODULE 004 COMPREHENSIVE EXAM

PORTAGE LEARNING

GENAVA COLLEGE

,THIS DOCUMENT CONSISTS OF THE
FOLLOWING
 Module 4 Exam

 True & False Questions

 Multiple Choice Questions and Answers

 Expert-Verified Explanations

, BIOD 171 MODULE 004 COMPREHENSIVE
EXAM

1. A researcher is asked to determine which of two vials contains *E. coli* and which contains
*Salmonella*. Knowing both are Gram-negative and only one can ferment lactose, which type of
media would be best suited?
Answer choices:
A. Selective media
B. Differential media
C. Enriched media
D. Minimal media
Correct Answer: B. Differential media
Expert Rationale: Differential media such as MacConkey agar incorporate lactose and a pH indicator,
enabling the differentiation of lactose fermenters (*E. coli*, producing pink colonies) from non-fermenters
(*Salmonella*, producing colorless colonies). This property makes differential media ideal for distinguishing
these two Gram-negative species based on metabolic activity.


2. True or False: Differential media is best suited for distinguishing between two similar species of
bacteria.


Answer choices:
- True
- False
Correct Answer: True
Expert Rationale: Differential media contain specific indicators (such as pH indicators or chromogenic
substrates) that exploit subtle metabolic differences between related microbes. Unlike simple growth media,
differential media enable visualization of phenotypic differences (e.g., fermentation of specific sugars),
thereby facilitating differentiation of closely related species.