Lab Activity — Blood Type Pedigree Mystery

“Easy,” said Leo. “If Ana and Carlos are both type A, they can’t have a type O child unless they’re both heterozygous AO.”

Therefore, the hypothesis that Claimant X is the biological offspring is as plausible. However, it is important to note that blood typing can only exclude paternity; it cannot confirm it with the certainty of DNA fingerprinting. This lab successfully demonstrated the predictive power of Punnett squares and the importance of understanding dominant, recessive, and codominant inheritance patterns in solving real-world biological problems.

The results of the lab activity present a complex genetic puzzle. Initially, the blood types of the parents (Type A and Type B) seem compatible with almost any blood type in the offspring, provided the parents are heterozygous.

Here’s a short draft for a lab activity story titled lab activity blood type pedigree mystery

However, many "mystery" variations of this lab present a twist. If the lab scenario stipulated that Mr. Rich had Type AB blood (a common variation of this mystery), the conclusion would be different.

“Punnett square,” Priya said. They worked it out: Possible offspring from AO x AB = AA, AB, AO, BO. That’s types A, AB, and B.

The Punnett square analysis confirms that if both parents are heterozygous ($I^A i$ and $I^B i$), there is a 25% probability of them producing a Type O child. Therefore, for Claimant X to be the biological son of Mr. and Mrs. Rich, provided the parents are heterozygous. “Easy,” said Leo

| | | $i$ (Mother) | | :--- | :--- | :--- | | $I^A$ (Father) | $I^A I^B$ (Type AB) | $I^A i$ (Type A) | | $i$ (Father) | $I^B i$ (Type B) | $ii$ (Type O) |

: Joseph intended to leave his fortune only to biological blood relatives . 🧬 Key Learning Concepts

Dr. Reeves handed them a sealed evidence bag. Inside: a worn hospital wristband labeled This lab successfully demonstrated the predictive power of

The purpose of this lab was to utilize ABO blood typing and pedigree analysis to resolve a familial mystery. Through the analysis of agglutination, the phenotypes of the subjects were determined. By applying Mendelian genetics and the laws of segregation, it was determined that a Type A father and Type B mother can produce a Type O child, provided both parents are heterozygous ($I^A i$ and $I^B i$).

This lab is a staple in high school biology for three reasons:

This laboratory activity investigates the principles of human genetic inheritance through the analysis of ABO blood types. By simulating a scenario involving a disputed inheritance, students utilize Punnett squares and pedigree analysis to determine the validity of a claimant’s biological relationship to a deceased individual. The experiment tests the predictability of Mendelian inheritance and codominance. Results indicate that the claimant’s blood type is genetically impossible given the phenotypes of the alleged parents, thereby disproving the biological relationship. This activity reinforces the practical application of immunology and genetics in forensic science.