General Biology Activity

The Baby Blunder


Early this morning, five baby boys were born at Gregor Mendel Hospital. The delivery ward was understaffed and overworked, and so the newborns were accidentally tagged with the names of the wrong parents.


To determine the blood types of the babies, and, using this information, reunite them with their real parents.


  1. Read the attached information about the ABO Blood Typing System, Antigens, Antibodies, and Cross Reactions.
  2. Examine the Standards for Blood Typing card. This card shows the results of mixing different types of blood with anti-A and anti-B antiserum (antibodies present in blood). Note the clumping of red blood cells that results when type A blood is mixed with anti-A serum, or type B blood is mixed with anti-B serum.
  3. Now examine the blood typing results for the five newborns. In each case, a drop of the baby’s blood was mixed with anti-A antibodies, and another drop was mixed with anti-B antibodies. If the baby’s red blood cells include the surface antigen A, the baby’s blood will agglutinate (RBCs will clump) when anti-A antiserum is added to the baby’s blood. This means the baby’s blood is type A. If the baby’s blood agglutinates when anti-B antiserum is added, then the baby has type B blood. If the baby’s blood agglutinates in both anti-A and anti-B, the baby has type AB blood, and if it doesn’t agglutinate in either antibodies, the baby has type O blood.
  4. Determine the blood type and possible genotypes of the five babies and enter this information in Table 1 .
  5. Now complete Table 2 on the next page by determining the genotypes of each of the parents, based on the information provided.
  6. Complete a  Punnett square for each couple, using the genotypes you determined in step 5.
  7. Finally, match each baby with his real parents. J


Text Box: Table 1. Blood Types of Newborns
Blood Type
Possible Genotypes
Baby 1
Baby 2
Baby 3
Baby 4
Baby 5


Results of Blood Tests Babies 1 – 5

Anti A        Anti B


Baby #1

Baby #2

Baby #3

Baby #4

Baby #5


Table 2. Information Obtained from Parents

Parents Names

Blood Types

Genotypes of the Parents

Carrie and Gene O’Type

Type O X Type O


Hettie and Homer Zygous

Type AB X Homozygous Type A


Allie and Leo Punnett

Heterozygous Type A X Heterozygous Type B


Polly and Otto Zome

Heterozygous Type B X Type O



To match parents with babies, complete the following Punnett squares for each couple using the genotypes in Table 2 above. Note: Baby #2 and Baby #3 are fraternal twins.



Carrie and Gene O’Type

____________ ´ ____________







Parents of _____________________


Allie and Leo Punnett

____________ ´ ____________







Parents of _____________________


Hettie and Homer Zygous

____________ ´ ____________







Parents of _____________________


Polly and Otto Zome

____________ ´ ____________







Parents of _____________________


This information may help with the above lab:

Standards for Blood Typing                                                                      

Blood being tested                               Blood Type


Text Box: Type O (contains neither A nor B antigen, clumps with neither antibody)
Text Box: Type A (contains antigen A, clumps with antibody A)
Text Box: Type B (contains antigen B, clumps with antibody B)
Text Box: Type AB (contains antigens A and B, clumps with both A and B antibodies)



ABO Blood Typing System

The major blood typing system used in the world.

Based on the presence of certain types of proteins on the surface of the red blood cells (RBCs)

These proteins are called antigens


In the ABO system

·         Type A blood has RBCs with A antigens

·         Type B has B antigens

·         Type AB has both A and B antigens

·         Type O has neither A nor B antigens


Type A (IA)  and Type B (IB) alleles are codominant

Type O (i) allele is recessive to A and B



Blood plasma contains proteins called antibodies which bind to antigens.

·         A antibodies (anti-A) bind to A antigens

·         B antibodies (anti-B) find to B antigens

Each particular blood type has the opposing antibody in the blood plasma (type A blood contains anti-B antibody, etc.)











Cross Reactions

When RBCs of one type are exposed to opposing antibodies, cross reactions occur.

The antibodies bind to the surface antigens, causing agglutination (clumping) of the RBCs.

The cells eventually hemolyze (blow apart)