Exemplar Dish environments are extremely simple. Researchers needed to see if cellular reprogramming would safely work inside a complex, living creature with real blood flow, internal systems, and active immune defenses without causing adverse reactions.
Rubric: Mentions "complex living body systems" 2 PTS
4
The results were incredible! The livers of infected armadillos grew 50% larger... they had no signs of scars or tumors.
Exemplar First, the expanded livers were completely healthy and worked perfectly (they maintained normal metabolic functions). Second, there were absolutely no signs of cellular scars or dangerous tumor growths.
Rubric: Must mention BOTH "functional" & "no tumors/scars" 2 PTS
5
No one wants to infect humans with leprosy... if we can understand exactly how these bacteria trick the liver, we might copy this cellular process without using bacteria at all!
Exemplar Scientists can study the specific genetic pathways/signals the bacteria use. By copying or "mimicking" these cellular commands, doctors could someday stimulate safe liver regeneration in humans using safe synthetic therapies, completely bypassing the leprosy bacteria itself.
Rubric: Mimicking the pathways without the pathogen 2 PTS
Teacher Key • Cellular Biology & Regeneration Page 2 of 4 6th Grade Science Lesson Resource
Organ Hackers Answer Key Part 3: Data Analysis Guide
Figure 2 Data Reference Points:
Uninfected Control Group: Average Liver-to-Body Weight Ratio: 0.018
Infected Experimental Group: Average Liver-to-Body Weight Ratio: 0.027
1. Analyze the Averages: What was the average liver-to-body-weight ratio for uninfected armadillos? What was it for infected ones? Which group had a higher average ratio?
Exemplar The average liver-to-body-weight ratio was 0.018 for the uninfected control group and 0.027 for the infected experimental group. The infected group had a significantly higher average ratio (50% greater).
Teacher Note: Ensure students read the dashed averages directly off the vertical axis labels.
2. Variables & Purpose: Why did scientists measure the liver-to-body-weight ratio instead of just weighing the liver on a scale by itself?
Exemplar Living armadillos come in different overall sizes. A larger armadillo will naturally have a heavier liver simply due to its body size. By using a ratio (liver weight divided by body weight), scientists controlled for body size, ensuring they measured relative organ growth rather than just the natural size differences of individual animals.
Teacher Note: This checks understanding of standardized variables and controls in animal biology.
3. Claim, Evidence, Reasoning (CER): Write a claim answering: Does leprosy bacteria make armadillo livers grow larger? Use specific evidence (numbers) from the graph to support your answer.
Claim: Yes, infection with leprosy bacteria triggers massive, healthy liver growth in armadillos.
Evidence: The average liver-to-body-weight ratio for infected armadillos (0.027) is 50% higher than the control group (0.018). The highest individual infected ratio is roughly 0.045, whereas control animals never exceed 0.031.
Reasoning: Because the body size was controlled via ratio, and the only experimental difference was the bacterial infection, the dramatic increase in the liver-to-weight ratio proves the leprosy bacteria induced organ growth.
Teacher Note: Give partial credit if evidence (numbers) or logical reasoning is absent.
Teacher Key • Cellular Biology & Regeneration Page 3 of 4 6th Grade Science Lesson Resource
Organ Hackers Answer Key Part 4: Understanding & Synthesis Solutions
Use these rubric-level exemplars to score the critical-thinking questions. Encourage peer grading discussions based on these responses.
On a genetic level, the bacteria alter the cell's gene expression. It effectively hacks the cells' DNA to turn on (activate) specific youth and growth-related genes that are usually dormant in adult animals, while simultaneously turning off (suppressing) genes that drive cellular aging.
Adult cells have fixed, specialized structures and cannot easily replicate to build new tissues. Reverting them back into young, unspecialized stem cells restores their ability to multiply rapidly and specialize into any type of cell required, allowing scientists to "build" new, functional organ layers.
Regenerating organs solves two massive clinical problems: first, it bypasses the severe organ donor shortage so patients don't have to wait years. Second, because the regenerated organ would be grown from the patient's own reprogrammed cells, it would be a perfect genetic match, completely eliminating the risk of immune rejection.
(Accept any scientifically sound proposal) Exemplar: Scientists should isolate the specific chemical compounds or proteins released by the leprosy bacteria during infection and try to apply them to adult human liver cells in a petri dish. This would test if the chemical trigger works on human tissue without introducing the actual pathogen.
Teacher Note: Highly encourage student creativity. Ensure they include "Reasoning" explaining what their proposed experiment intends to prove.
Teacher Key • Cellular Biology & Regeneration Page 4 of 4 6th Grade Science Lesson Resource
