Cell Entry & Internal Transport Breakdowns
3
Cell Gate Failure
A. Targeted Molecule(s):
Glucose (blocked from crossing cell membrane).
B. Missing Helper Protein:
Insulin (normally produced in the pancreas).
C. Cellular Delivery Roadblock (Mechanism):
Expected Response: Glucose enters blood normally from the gut, but the pancreas fails to produce insulin. Insulin acts like a key to unlock cell membranes. Without insulin, glucose cannot enter cells and stays trapped in the blood, leading to high blood glucose while cells starve for fuel.
D. Metabolic Impact:
Mitochondria inside cells lack fuel, halting cellular respiration and causing profound energy loss and fatigue.
E. Medical Treatment:
Injecting insulin supplies the missing key to unlock membranes, allowing glucose to enter cells and restoring normal metabolism.
4
Circulatory Transport Deficit
A. Targeted Molecule(s):
Oxygen (\(\text{O}_2\)) transport to body cells.
B. Deficient Blood Component:
Red Blood Cells (RBCs) / Hemoglobin; Iron mineral.
C. Cellular Delivery Roadblock (Mechanism):
Expected Response: The lungs take in plenty of oxygen from the air, but the circulatory system has too few red blood cells (due to lack of iron). There are not enough carriers to transport oxygen from the lungs to cells throughout the body.
D. Metabolic Impact:
Cells lack the oxygen needed to react with glucose to produce ATP, causing fatigue, dizziness, and fainting episodes.
E. Medical Treatment:
Iron pills and iron-rich foods (beans, meat, spinach) give the body the mineral needed to manufacture healthy red blood cells.
Diagnostic Comparison Matrix
| Condition | Blocked Molecule | Where Breakdown Occurs | How Cells Are Starved |
|---|---|---|---|
| Pancreas Injury | Glucose | Digestion in small intestine | Starch not broken down; cannot enter blood |
| Asthma | Oxygen | Lungs / Airway entry | Swollen tubes stop air from reaching alveoli |
| Diabetes | Glucose | Cell membrane entry gate | No insulin to unlock cell membrane |
| Anemia | Oxygen | Bloodstream transport delivery | Too few RBCs to carry oxygen to cells |
Metabolism Teacher Key • Cases 3 & 4 + Matrix Page 2 of 3
Part III
Scoring Guide • Scientific Explanation
Exemplar Student Response (Full Mastery) Model Answer
1. Exemplar Claim:
A breakdown in a single body system causes whole-body energy failure because cellular respiration requires both glucose and oxygen to produce ATP energy; if either molecule is blocked from reaching cells, cells cannot release energy.
2. Exemplar Evidence:
In diabetes, the patient ate normally and had high glucose in the blood, but without insulin to unlock the cell membrane, glucose could not enter the cells. In asthma, the patient breathed deeply, but swollen bronchial tubes choked off airflow, drastically reducing oxygen entering the blood. In both cases, cells failed to receive one of the needed molecules, resulting in severe fatigue.
3. Exemplar Reasoning:
Inside cells, mitochondria carry out cellular respiration: Glucose + Oxygen → Energy (ATP) + CO2 + H2O. This chemical reaction requires both reactants to work together. If a digestive breakdown (or membrane block) stops glucose, the cell has no fuel. If a respiratory or circulatory failure stops oxygen, the chemical reaction cannot release energy. Missing either molecule stops ATP production, causing the exact same symptom of cellular exhaustion.
CER 3-Level Evaluation Rubric
| Component | Mastery (3 pts) | Developing (2 pts) | Beginning (1 pt) |
|---|---|---|---|
| Claim | Accurately states that blocking either glucose or oxygen stops cellular energy production. | States that systems are connected or molecules are needed, but vague about energy. | Incomplete claim or simply states that diseases make people tired. |
| Evidence | Cites specific story data from at least 2 conditions (one glucose, one oxygen). | Cites only 1 condition or provides general descriptions without specific story evidence. | Does not cite story evidence or references incorrect molecules. |
| Reasoning | Explicitly links evidence to cellular respiration equation and why both reactants are needed for ATP. | Mentions cellular respiration or energy, but does not explain the biochemical reactant connection. | Simply restates evidence without connecting to scientific principles. |
Metabolism Teacher Key • CER Exemplar & Rubric Page 3 of 3
Cell Membrane Barrier
Case Profile
The Roadblock
Discussion: How can blood have too much sugar, while cells are starving for sugar?
4
Blood Transport Deficit
Case Profile
The Roadblock
Discussion: The lungs are full of oxygen. Why are the patient's brain cells still suffocating?
Summary Grid
Pancreas Injury Digestive Gut
Glucose
Starch not digested into glucose
Asthma Respiratory Entry
Oxygen
Swollen tubes choke off airflow
Diabetes Cell Membrane
Glucose
No insulin to unlock cell gate
Anemia Blood Highway
Oxygen
Too few red blood cells to deliver
Two conditions block Glucose • Two conditions block Oxygen
Whole-Class Challenge
Driving Question
4 patients have 4 completely different organ conditions.
Why do ALL FOUR suffer from the exact same symptom: extreme exhaustion?
Respiration Needs BOTH Reactants
Mitochondria cannot release energy with only glucose or only oxygen. Missing either reactant halts ATP production!
Targeted Medical Treatments
Treatments restore molecular delivery: enzyme pills, inhalers, insulin shots, or iron supplements!
Next: Use your table evidence to complete the CER Argument on Page 3!
Page 3 Checklist
1. CLAIM
Answer the Question
State directly how blocking either molecule stops cellular energy release throughout the body.
2. EVIDENCE
Cite 2 Patient Stories
Include real facts from 1 glucose case (Pancreas/Diabetes) AND 1 oxygen case (Asthma/Anemia).
3. REASONING
Explain the Science
Connect evidence to the cellular respiration equation in mitochondria (Glucose + Oxygen → ATP Energy).
Remember: Strong reasoning explains WHY the evidence supports the claim! Printable Page 3
