1. Which of the following is NOT a phase of microbial growth? A. Lag B. Log C. Stationary D. Decline Answer: D. Decline Rationale: The decline phase is not typically considered a standard phase of microbial growth. The recognized phases are lag, log (or exponential), stationary, and death. 2. What is the primary purpose of using selective growth media? A. To support the growth of all microbes present B. To inhibit the growth of certain microbes C. To identify specific metabolic processes D. To count the number of colonies Answer: B. To inhibit the growth of certain microbes Rationale: Selective growth media are designed to favor the growth of particular microorganisms and inhibit the growth of others, allowing for isolation and identification of specific species. 3. MacConkey Agar is an example of which type of growth media? A. Universal B. Selective C. Differential D. Both B and C Answer: D. Both B and C Rationale: MacConkey Agar is both selective, as it inhibits the growth of Gram-positive bacteria, and differential because it distinguishes between lactose fermenters and non-fermenters based on colony color. 4. In the context of microbial growth, what does the term 'colony-forming unit' (CFU) refer to? A. A single cell or group of related cells that gives rise to a colony B. The initial inoculum size C. The total number of viable microbes D. A measure of bacterial motility Answer: A. A single cell or group of related cells that gives rise to a colony