Heredity – Biology

Part 1:

Test the family members for the following hereditary traits. Each member of the family should complete all the tests. The tests will determine the phenotypes of the family members:

1. Tongue test: Try to roll your tongue into a tube. If you can do it, your phenotype is (T). If you cannot roll your tongue, your phenotype is (t).
2. Hair test: Do you have dark hair (H) or blond or red hair (h)?
3. Eyes test: Do you have blue eyes (b) or non-blue eyes (B)?
4. Ear test: Are your ear lobes unattached (E) or attached (e)?

Create a phenotype table in the submission box and report on the results of the tests. Your data table should look similar to this one. (but it will have different data in the boxes) Do not go on to part 2 until your teacher approves your data table.

Part 2:

Consider each of the Punnett squares below. They show the results of crossing different mother and father genotypes. In each case, “A” represents the dominant allele and “a” represents the recessive allele.

Two Punnett squares have been left out: the squares representing a cross between different phenotypes. What are the genotypes that would be crossed in each of the two missing tables? Submit your answer to your teacher but do not go on to part 3 until your teacher approves of your answer.
 

aa x aa: neither parent expresses dominant trait

children’s phenotypes are all a
 

Aa x Aa: both parents express dominant trait

children’s phenotypes are either A or a
 

AA x Aa: both parents express dominant trait

children’s phenotypes are all A
 

AA x AA: both parents express dominant trait

children’s phenotypes are all A

Part 3:

Create tables to show the two missing Punnett squares. Submit the tables to your teacher and do not go on to part 4 until your teacher approves of your tables.

Part 4:

For each of the four traits, decide which of the possible genotype crosses could represent the family you studied. For example, if both parents express the dominant trait, and only two of three children express the dominant trait, then the parents must be Aa and Aa. Otherwise, if the parents were (AA and Aa) or (AA and AA), all of the children would express the dominant trait. Only the AaxAa table is consistent with two dominant phenotype parents having children that are both dominant and recessive phenotypes.

Remember that in each case, the capitalized phenotype (T, H, B, E) represents expression of the dominant gene, and the lower-case phenotype (t, h, b, e) represents expression the recessive gene. Remember also that the phenotype T could be produced by the genotype TT or the genotype Tt, while the phenotype t can only be produced by the genotype tt.

Submit your conclusions about the genotypes of the parents for each of the four traits, and an explanation of how your data supports your conclusions. Use paragraphs with complete sentences and proper English grammar.

Not all browsers can use the form below to do the Punnett squares. You can create the a square on your computer (as a doc, rtf, gif or jpg file), and upload it to our server. Attach the punnet square here.