Genetics Puzzles

·        Solve the following genetics puzzles, writing neatly, showing your work. Use your own paper if you need more room. Show your “letter” alleles under the word Key

·        Scan or photograph, submit a PDF, PNG, or JPG (not HEIC) check after you submit that the file is easy to read/view

Example Problem: Gregor Mendel crossed garden peas to figure out patterns of heredity. One of the traits he examined was pea height. When he crossed pure-breeding tall peas with pure-breeding short peas, all of the resulting peas were tall. Show how this is possible.

Key                        Parental Genotype:                                                                                        Phenotype Ratio:

T=tall                                     TT x tt

T = short              Gametes possible from each parent:                                                                      100% Tall

                                TT will produce T gametes; tt will produce t gametes

                                Genotype Resulting From Cross:

                                                Tt

Key

1.  Garden peas exhibit dominance of purple flower petals over white petals.  What will result from a cross between a homozygous dominant pea flower and a homozygous recessive pea flower?  Show the genotype (the gene pairs possible) and the phenotype ratio (the physical appearance).

Key                                        Parents Genotype:                                                                                         Phenotype Ratio:

2. You are growing flowers for a homecoming event and need to have displays with 50% of the zinnias blue and 50% of the zinnias white.  What are the possible phenotypes of the cross between heterozygous blue zinnias and white zinnias (homozygous recessive)? Will this cross give you the correct percentage of flower colors needed? Show the genotype and phenotype ratio.

Key                                        Parents Genotype:                                                                                         Phenotype Ratio:

3. Albinism is recessive and a pair of albinism alleles prevents the production of melanin; this is the pigment that creates brown coloration. Show how two parents that appear normal in their skin pigmentation could have a child with albinism. What is the probability of this couple having a child with albinism?

Key                        Parents Genotype                                                                                           Probability:                       

4. Color blindness is a recessive X-linked trait.  If the father is colorblind and the mother is a carrier (heterozygous), could this couple have any colorblind girls?

Key                        Parents Genotype:                                                                                         Probability:

5. It is not common but it does happen, there has been a suspected baby mix-up at a rural hospital. A woman has type AB blood. Could this woman be the mother of a child with type B blood? If so, what blood type(s) could the father have (if the man IS the father and the child has type B blood)?

Key