Part 1
A: In the pea plant, the purple color is the dominant one while the white color is the recessive color. The F1 offspring that had purple colored flowers were 445 while those that had white colored flowers were 437. This gives a phenotypic ratio of almost 1:1. To attain this ratio, a parent with white colored flower (pp) had to be crossed with a heterogeneous purple colored parent (Pp). This can be confirmed by crossing the two patents as shown in the Punette square below.
B: The pattern observed can be explained using the first law of inheritance also called the Law of Segregation. The law hypothesizes that every individual has a pair of alleles expressing a particular trait, and each offspring receives a copy or allele that is randomly selected from each of the two parents. This results in the offspring getting two copies of the same trait from each parent to make a pair of the alleles. In the process of cell division, the alleles separate from each other and form gametes each with one copy of the allele. The gamete from one parent joins together with the gamete from the other parent during reproduction bringing the two alleles together to form a diploid cell.
Part 2
The purple flowered plants resulting from the above F1 generation are all heterogynous (Pp). A cross of these plants through self-fertilization results in both white and purple flower colored pea plants at a phenotypic ratio of purple: white of 3:1 and a genotypic ratio of PP: Pp: pp of 1:2:1. The crossing may take place as shown in the punette square below.
Part 3
A: When the a heterozygous purple tall plant (PpTt) is crossed with a white dwarf plant (pptt), the F1 generation offspring include purple tall plants, purple short plants, white purple plants and white dwarf plants. The probability that a white dwarf pea plant will be produced is 25% as shown in Punette square below.
- This prediction works using the law that is known as the Independent Assortment Law. The law is also called the Inheritance Law and states that genes responsible for different traits are passed independently from the parents to the siblings. This means that the gene of a particular trait does not affect the selection of another gene for a different trait. During cell division, separation of alleles for a particular trait takes place independently and are then assorted independently during gamete fusion to form a diploid cell that forms an individual. Therefore, the color and height alleles separated independently and later assorted themselves independently to form the 16 possible outcomes.
