WGU D311 Task 2 | Unknown Lab Manual 9 | Latest
2025/2026 Update with complete solutions.
MICROBIOLOGY WITH LAB: A FUNDAMENTAL
APPROACH
Task 2: Unknown Lab Manual 9
The goal in this Task 2 lab is to identify an unknown that learners might encounter in the real
world using the least number of instruments and tools as possible while still replicating the
problem-solving purpose of the lab experience. Learners will be provided with lab evidence and
will need to determine the next test steps until a final identification is confirmed. This lab will
encourage critical thinking, analysis, reasoning, and decision-making that forges connections
among complex systems while solving a problem.
Task Instructions
Welcome to Unknown 9 Lab! Your goal in this lab is to use various laboratory tests to identify
an unknown organism. Before proceeding, double check that you have selected the correct
group based on the first initial of your last/family name.
In a laboratory setting, your time and resources are limited. While the results of several tests are
provided in this manual, remember that you will not use every test to make an identification.
Instead, use the provided decision tree to choose each next step, narrow down your choices,
and identify your unknown organism.
In your lab report, you will only be discussing the Gram stain and two additional tests that you
selected based on the decision tree and your results. You will be asked to explain your
reasoning for each test that you select. Once you have identified your unknown organism, you
will use the results of the Kirby-Bauer diffusion test to select an antibiotic for treatment.
Important
1. Use the decision tree provided below. Refer to Section 4, Lesson 2.7 to reference the
decision tree directions and to view a larger image. As a reminder, the decision tree will
guide you in making decisions about which tests to explore along the journey to identify
your unknown organism.
2. Save your lab report as a Word document, titled D311 Task 2 Lab Report Last Name.
3. In your lab report, indicate which unknown organism number you will identify, or your
work will be returned to you without evaluation.
4. This lab manual can be used as a template for your lab report. Answer the questions as
you complete each test.
Western Governors University 1|Page
,Decision Tree
Lab Manual Navigation
Decision Tree (p2) Citrate test (p7) Coagulase test (p12)
Gram stain results (p3) Voges-Proskauer test (p8) Motility test (p13)
Endospore stain (p4) Glucose fermentation (p9) Kirby-Bauer (p14)
Capsule stain (p5) Lactose fermentation (p10)
Blood agar growth (p6) Catalase test (p11)
Western Governors University 2|Page
, Gram Stain
1. Identification of your unknown bacterial specimen will begin with the Gram stain.
2. Observe the Gram stain results.
Gram Stain Results
3. Describe the color and morphology of the cells.
· Is this organism Gram-positive or Gram-negative? What evidence supports your
reasoning?
· Is this organism's morphology bacillus- or coccus-shaped? What evidence
supports your reasoning?
4. In a laboratory setting, you would not be able to run all available tests on every
organism. Choose the next test based on the Gram stain results using the Decision
Tree. Explain why you chose the next test.
Lab Manual Navigation
Decision Tree (p2) Citrate test (p7) Coagulase test (p12)
Gram stain results (p3) Voges-Proskauer test (p8) Motility test (p13)
Endospore stain (p4) Glucose fermentation (p9) Kirby-Bauer (p14)
Capsule stain (p5) Lactose fermentation (p10)
Blood agar growth (p6) Catalase test (p11)
Western Governors University 3|Page
2025/2026 Update with complete solutions.
MICROBIOLOGY WITH LAB: A FUNDAMENTAL
APPROACH
Task 2: Unknown Lab Manual 9
The goal in this Task 2 lab is to identify an unknown that learners might encounter in the real
world using the least number of instruments and tools as possible while still replicating the
problem-solving purpose of the lab experience. Learners will be provided with lab evidence and
will need to determine the next test steps until a final identification is confirmed. This lab will
encourage critical thinking, analysis, reasoning, and decision-making that forges connections
among complex systems while solving a problem.
Task Instructions
Welcome to Unknown 9 Lab! Your goal in this lab is to use various laboratory tests to identify
an unknown organism. Before proceeding, double check that you have selected the correct
group based on the first initial of your last/family name.
In a laboratory setting, your time and resources are limited. While the results of several tests are
provided in this manual, remember that you will not use every test to make an identification.
Instead, use the provided decision tree to choose each next step, narrow down your choices,
and identify your unknown organism.
In your lab report, you will only be discussing the Gram stain and two additional tests that you
selected based on the decision tree and your results. You will be asked to explain your
reasoning for each test that you select. Once you have identified your unknown organism, you
will use the results of the Kirby-Bauer diffusion test to select an antibiotic for treatment.
Important
1. Use the decision tree provided below. Refer to Section 4, Lesson 2.7 to reference the
decision tree directions and to view a larger image. As a reminder, the decision tree will
guide you in making decisions about which tests to explore along the journey to identify
your unknown organism.
2. Save your lab report as a Word document, titled D311 Task 2 Lab Report Last Name.
3. In your lab report, indicate which unknown organism number you will identify, or your
work will be returned to you without evaluation.
4. This lab manual can be used as a template for your lab report. Answer the questions as
you complete each test.
Western Governors University 1|Page
,Decision Tree
Lab Manual Navigation
Decision Tree (p2) Citrate test (p7) Coagulase test (p12)
Gram stain results (p3) Voges-Proskauer test (p8) Motility test (p13)
Endospore stain (p4) Glucose fermentation (p9) Kirby-Bauer (p14)
Capsule stain (p5) Lactose fermentation (p10)
Blood agar growth (p6) Catalase test (p11)
Western Governors University 2|Page
, Gram Stain
1. Identification of your unknown bacterial specimen will begin with the Gram stain.
2. Observe the Gram stain results.
Gram Stain Results
3. Describe the color and morphology of the cells.
· Is this organism Gram-positive or Gram-negative? What evidence supports your
reasoning?
· Is this organism's morphology bacillus- or coccus-shaped? What evidence
supports your reasoning?
4. In a laboratory setting, you would not be able to run all available tests on every
organism. Choose the next test based on the Gram stain results using the Decision
Tree. Explain why you chose the next test.
Lab Manual Navigation
Decision Tree (p2) Citrate test (p7) Coagulase test (p12)
Gram stain results (p3) Voges-Proskauer test (p8) Motility test (p13)
Endospore stain (p4) Glucose fermentation (p9) Kirby-Bauer (p14)
Capsule stain (p5) Lactose fermentation (p10)
Blood agar growth (p6) Catalase test (p11)
Western Governors University 3|Page
