Joana Ricou

This exhibit represents four planted Punnett Squares. The two on the top represent self-reproduction of white and yellow plants (G0); the bottom left represents the cross-fertilization of a white and yellow plant (their offspring is G1); the bottom-right square represents the cross- or self-fertilization of G1.

This display illustrates basic inheritance in the first two squares, dominance in the third and recessive traits in the last.

The Punnett square (left) allows us to determine the ratio of genotypes of the offspring based on the genotypes of the parents. In the simplified version, all possible genotypes are included in each section.

This display introduces a simplified version of the Punnett square. The simplification includes the grouping of genotypes and also the assumption that the trait in question is only determined by one gene.

This simplification allows us to illustrate the Punnett square with planted flowers were alleles would normally go. Casual visitors are challenged to interpret the patterns found, and discover the basic laws of inheritance.

The interpretation of the squares is helped by signage as represented by the image to the top right.

Squares numbered from left to right:
- Squares 1 and 2 represent self-fertilization of white or purple flowers. These squares show that the offspring look like the parents, suggesting that the offspring inherit all their traits from its parents.
- Square 3 presents cross-fertilization of purple and white flowers. The offspring are all purple, showing that some traits are dominant over others. Ie, the purple color is dominant over the white color.
- Square 4 presents a challenge to the visitor, how can two purple flowers produce a white flower? Due to recessive genes! A purple flower can carry a dominant purple allele that hides a white allele. When two such flowers are crossed, one fourth of the time Crossing two flowers of this kind would create a white flower.

The magnetic Punnett square board installed at Phipps Conservatory.

Punnett Square Magnetic Board
This tool lets teachers guide their students in translating their understanding of what is happening at the phenotype level to the genotype level.

Darwin2009: Magnetic Punnett Square Magnetic Board

During special education events or for class tours, the magnetic board was made available.

Re-Inforcing Exhibits
A teacher can introduce Mende’s inheritance with the Plant Pyramids then delve deeper into Punnett’s genetics with the Genetic Garden. The color scheme re-enforces the theme presented in the reproduction pyramids.

Education Extension
The lesson plan “Family Trees,“ a class can create or plant their own Genetic Garden and a magnetic Punnett Square board.

Grades 4- 7
CONCEPTS
Self- and cross- fertilization
Inheritance
Dominance
Reproduction and variation

Darwin2009: Exhibit at Phipps Conservatory