Before revealing the answer key, we must align on the updated (UPD) genetic rules. The old keys sometimes ignore the cis-AB or Bombay phenotype, but for standard high school level, we stick to the core rules:
| Blood Type (Phenotype) | Possible Genotypes | Antigen on RBC | Antibody in Plasma | | :--- | :--- | :--- | :--- | | A | IAIA or IAi | A antigen | Anti-B | | B | IBIB or IBi | B antigen | Anti-A | | AB | IAIB | A and B antigens | None | | O | ii | None (H antigen only) | Anti-A and Anti-B |
Critical Rule for Pedigrees:
The Blood Type Pedigree Mystery is more than just a puzzle; it is an exercise in deductive reasoning. By understanding the interaction of multiple alleles and utilizing pedigree charts, students can definitively prove or disprove biological relationships. In the case of the standard mystery scenario, the presence of a Type B child to Type A and O parents serves as the "smoking gun," revealing the fraudulent claim and solving the mystery.
Lab Activity: Blood Type Pedigree Mystery
Introduction
Have you ever wondered how blood type is inherited? Or how to determine an individual's blood type based on their family history? In this lab activity, we will explore the fascinating world of blood type genetics and solve a pedigree mystery.
Background
Blood type is determined by multiple alleles (forms) of the ABO gene. The ABO gene codes for an enzyme that modifies the carbohydrate molecules on the surface of red blood cells. The three main alleles are:
The possible genotypes and phenotypes for ABO blood type are:
| Genotype | Phenotype (Blood Type) | | --- | --- | | AA or AO | A | | BB or BO | B | | AB | AB | | OO | O |
The Pedigree Mystery
Meet the Smith family:
Can you determine the genotypes of each family member?
Step 1: Determine the Genotype of the Parents
John has blood type A, which means his genotype can be either AA or AO. Since Mary has blood type O, her genotype must be OO.
Step 2: Determine the Possible Genotypes of the Children
Using a Punnett square, we can predict the possible genotypes and phenotypes of the children:
| | O | O | | --- | --- | --- | | A | AO | AO | | A | AO | AO |
The Punnett square shows that John (A) and Mary (O) can have children with genotypes AO or OO.
Step 3: Analyze the Children's Blood Types
The Mystery Unfolds
It turns out that John's parents were both carriers of the B allele. John's mother had blood type B, and his father had blood type A. This means John inherited a B allele from one of his parents, making his genotype AB (not AA or AO).
The Complete Pedigree
Here is the updated pedigree:
Conclusion
In this lab activity, we solved a pedigree mystery by applying our knowledge of blood type genetics. We determined the genotypes of each family member and uncovered the unexpected inheritance of a B allele in John. This activity demonstrates the importance of understanding genetic principles to analyze and predict the inheritance of traits. lab activity blood type pedigree mystery answer key upd
Answer Key
Discussion Questions
Extension Activity
Create a pedigree for a fictional family with a mystery trait. Use genetic principles to determine the genotypes and phenotypes of each family member. Share your pedigree with the class and see if they can solve the mystery!
In the sterile glow of the Neo-Gene Lab, Dr. Aris Thorne stared at the digital pedigree chart glowing on his tablet. The family tree belonged to the Montgomerys, a lineage of old wealth, but it was currently telling a story of biological impossibility.
The patriarch, Arthur Montgomery, was an uncompromising man with blood type A. His wife, Eleanor, possessed the rare and elusive blood type O. By all the laws of basic Mendelian genetics, their children should have been either type A or type O. Yet, their youngest daughter, Clara, was sitting in the clinic with a confirmed blood type of AB.
"An absolute impossibility," Aris whispered to himself, pacing the narrow aisle between the centrifuges.
In any standard classroom lab activity, this was the classic "Pedigree Mystery." Students would immediately point fingers at infidelity or a mix-up at the hospital. But Aris knew this family. Arthur had shielded Clara since the day she was born, and the hospital records from twenty years ago were flawless.
Aris pulled up the raw data from Clara's deep gene sequencing. He wasn't looking at a simple Punnett square anymore. He was looking at the actual molecular structure of her chromosomes.
He scrolled past the standard markers, his eyes burning from hours of staring at the blue light. Then, he saw it. A strange, silent anomaly in her H-antigen locus.
He held his breath and opened the file for Clara's mother, Eleanor. On paper, Eleanor was blood type O. But as Aris looked at the specific alleles, the truth clicked into place with the chilling precision of a deadbolt.
Eleanor didn't actually have blood type O alleles. Genetically, Eleanor was blood type B.
She possessed the incredibly rare Bombay phenotype. Because she lacked the ability to produce the H-antigen—the chemical base required to make A or B antigens attach to red blood cells—her blood tests always defaulted to type O. She was a genetic chameleon. She carried the functional B gene, but it was masked, hidden in plain sight for her entire life.
Eleanor had passed that hidden B gene to Clara. Arthur had passed his dominant A gene. In Clara, who did not inherit the Bombay phenotype, both genes expressed themselves perfectly.
Aris leaned back in his chair, the mystery solved. It wasn't a story of betrayal or a clinical error. It was a masterpiece of recessive genetic camouflage. He saved the annotated pedigree file and closed his laptop, ready to deliver the news that would keep a family's history intact.
Blood Type Pedigree Mystery lab activity, the thief is identified as . Based on the clues provided in the scenario, has blood type attached earlobes , matching the evidence collected at the crime scene. Course Hero 1. Identify inheritance patterns
The lab focuses on two distinct inheritance patterns to solve the mystery: Ear Lobe Attachment : This is an autosomal recessive
trait. Free earlobes are dominant (F), while attached earlobes are recessive (f). Individuals with attached earlobes must have the genotype ABO Blood Types : This involves multiple alleles cap I to the cap A-th power cap I to the cap B-th power codominance cap I to the cap A-th power cap I to the cap B-th power
are codominant to each other and both are dominant over the recessive
: Inherited independently of the ABO group, where Rh+ is dominant over Rh-. 2. Determine Joseph's genotype
To solve the pedigree, you must work backward from the children's blood types to find the father's (Joseph) missing information: : Joseph has : His genotype is cap I to the cap B-th power i for blood type and (heterozygous) for the Rh factor. : Since Joseph and Rita (who is cap I to the cap A-th power cap I to the cap B-th power
) have a child with Type O blood or contribute to children with diverse types like A and B, Joseph must carry the recessive allele and the recessive allele to allow for Rh- offspring. 3. Analyze the suspects and family data
The following table summarizes the key family members and their traits used to narrow down the thief: Blood Type Earlobe Trait Genotype (Blood/Lobe) Father/Grandfather cap I to the cap B-th power i Mother/Grandmother cap I to the cap A-th power cap I to the cap B-th power cap I to the cap A-th power i Granddaughter cap I to the cap A-th power i 4. Solve the mystery The crime scene evidence consists of Type A- blood attached earlobes Course Hero Suspect Identification
: While several family members have Type A blood or attached earlobes, is the only one who possesses both traits simultaneously.
: The lab suggests her motive may involve her brother, Joey, who has O+ blood; she may have mistakenly believed he would be excluded from the inheritance and sought to take the money herself. Course Hero The thief of the money is
was determined to be the thief because her phenotype (Type A- blood and attached earlobes) matches the biological evidence found at the scene, and her genotype ( cap I to the cap A-th power i Before revealing the answer key, we must align
) is a mathematically possible outcome from her parents' (Claire and Paul) genetic cross. Course Hero to see the probability of specific genotype?
Blood Type Pedigree Mystery Analysis | PDF | Genotype - Scribd
Determine the genotypes for blood type of Joseph and his family members. Since you don't know Joseph's genotype, you will need to.
Blood Type Pedigree Mystery Analysis | PDF | Genotype - Scribd
Here’s a draft for a post announcing the update to your “Blood Type Pedigree Mystery” answer key. You can adjust the tone depending on your audience (e.g., teachers vs. students).
Option 1: For Teachers / Educator Group (e.g., Facebook group, blog, email)
Title: 🔬 Lab Activity: Blood Type Pedigree Mystery – ANSWER KEY UPDATED
Hi everyone,
I’ve just uploaded an updated answer key for the “Blood Type Pedigree Mystery” lab activity.
What’s new in this version:
Who is this for?
Grades 9–12 Biology / Honors Genetics
Download here: [Insert link to Google Doc, TpT, or Drive]
If you’ve purchased this before, just re-download the file for free. Let me know if you spot any issues!
Thanks,
[Your Name]
Option 2: For Students (after completing the activity – post only after they’ve submitted their work)
Title: 🧬 Blood Type Pedigree Mystery – Answer Key Now Available (UPDATED)
Hi class,
The updated answer key for our Blood Type Pedigree Mystery lab is now posted.
📌 Reminder: Please do not look at this until you’ve turned in your own work!
Use this to check your reasoning, especially:
👉 [Link to answer key PDF]
Let me know if you have any questions about the steps — happy to go over them in class tomorrow.
Mr./Ms. [Last Name]
Option 3: Short & Sweet (for LMS like Canvas, Google Classroom)
Subject: UPDATED – Blood Type Pedigree Mystery Answer Key
The answer key for the lab activity has been updated. Please download the latest version here: [link] The Blood Type Pedigree Mystery is more than
Changes: corrected genotype for individual I-2, added reasoning for question #5.
In the Blood Type Pedigree Mystery lab, the thief is identified as (or
). Her blood type is A+ and she has attached earlobes, which matches the evidence found at the scene. Joseph’s blood type is determined to be B+ with the genotype BOcap B cap O . 1. Determining Joseph’s Genotype
To find Joseph's blood type, you must work backward from his children's phenotypes. Joseph and Rita (Type AB-) have four children: (O-), Howard (AB-), (A+), and Danny (A-). is Type O- ( ): Since Rita is IAIBcap I to the cap A-th power cap I to the cap B-th power , she cannot provide an allele. However, the data lists
as a daughter of Joseph and Rita. In many versions of this mystery, Jane's Type O blood reveals she is either adopted or provides the key that Joseph must carry an is A+: Since Rita is Rh- ( ), the Rh+ allele ( ) must come from Joseph. Result: Joseph is Type B+ with the genotype . 2. Identifying the Inheritance Patterns The lab tracks two distinct genetic traits:
ABO Blood Type: Uses codominance (A and B are both expressed) and multiple alleles ( ). Type O is recessive.
Rh Factor & Earlobes: Both follow simple Mendelian inheritance. Rh+ ( ) and Free earlobes ( ) are dominant; Rh- ( ) and Attached earlobes ( ) are recessive. 3. Solving the Mystery
The crime scene evidence includes a blood smear (Type A-) and the thief's trait of attached earlobes. Suspect Analysis:
: Type A-, Attached earlobes. (Matches both evidence points). : Type A-, Attached earlobes. (Also matches, but
is often the designated "thief" in the answer key due to her specific motive). Motive:
motive is often linked to the belief that her brother (Justin, Type O+) would not inherit the family wealth due to his blood type being "different" from the rest of the family. Answer Key Summary Individual (Thief) Answer:The thief is because her blood type ( ) and attached earlobes (
) perfectly match the forensic evidence found at the Wexford estate safe. Blood Type Pedigree Mystery Lab Activity - TPT
For quick classroom reference, here is the clean answer key for the standard "Blood Type Pedigree Mystery Lab."
Case: Father (AB) x Mother (O)
Possible children: Type A or Type B only.
Excluded children: Type AB or Type O.
Claimant results:
Genotype assignments:
Pedigree reasoning: The AB father cannot contribute an i allele; therefore O child impossible.
Every year, biology teachers face the same challenge: how to make Mendelian genetics and immunology engaging without resorting to rote memorization. Enter the Blood Type Pedigree Mystery Lab Activity. This hands-on simulation combines the logic of a "whodunit" mystery with the rigorous science of ABO blood typing and pedigree analysis.
If you’ve searched for the phrase "lab activity blood type pedigree mystery answer key upd" , you are likely either:
This article serves as your ultimate resource. We will break down the mystery, provide the updated answer key, explain the science behind each conclusion, and discuss common student errors and how to correct them.
Answer: YES.
Mystery element: The servant claimed O is impossible. The servant is wrong – but wait, the lab says "Keep reading... the royal bloodline historically has never produced O."
So probability for an A− child = (25% for A) × (25% for −) = 6.25% per child under independent assortment.
Unlike simple Mendelian traits that have two alleles (e.g., tall vs. short), blood type is determined by three alleles: