Biology

Inheritance of genes explains all of the traits expressed in organisms, from the colors in pea plant flowers to patterns of baldness in adult humans. The work of Gregor Mendel (1822–1884) paved the way toward understanding dominant and recessive traits, and helped geneticists analyze the influence of genes on health, appearance, and sex.

Generation 1 (F1)

1. Drag one flower of pure breeding stock to each position next to the Punnett Square. The pure breeding stock serves as the parental generation. It is either dominant (PP) or recessive (pp). Use the mouse to place the cursor into each position on the Punnett Square and type in the correct genotype.
2. Click on the data table icon in the menu bar to open the data table. Fill in the table to record the genotype and phenotype for Generation 1 (F1) plants produced by the pure breeding flowers.

Generation 2 (F2)

1. Drag one flower from the F1 generation to each position next to the Punnett Square. Use the mouse to place the cursor into each position on the Punnett Square and type in the correct genotype.
2. Open the data table. Fill in the table to record the genotype and phenotype for Generation 2 (F2) plants produced by the F1 flowers.

1. In the F1 generation, what percentage of the plants had the purple phenotype? In the F2 generation?
2. If you wanted to raise all purple flowers for several generations, what breeding stock would you use? Why?
3. What breeding stock would produce white flowers for several generations? Why?
4. Besides color of flowers, there are thousands of other genetic traits in plants, including height of stem, shape of fruit, and color of fruit. What are some of the genetic traits in humans?

1. 100%; 75%.
2. PP; If "p" (white flower) genes are present, they will begin appearing after two or three generations.
3. pp; any P (purple flower) genes would mask the white flower genes.
4. Answers will vary; students might mention hair color, height, color of eyes, freckles, and attached or free earlobes.