Workout a cross between a homozygous tall pea plant with axial flower (TTAA) and a homozygous dwarf pea plant with terminal flower (ttaa) Note:(a)considering the table that provides and summarize the contrasting character of pea plant,(1)state the phenotype ratio of the F1 generation,(2)state the genotype ratio of the F2 generation
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To determine the phenotype and genotype ratios of the cross between a homozygous tall pea plant with axial flower (TTAA) and a homozygous dwarf pea plant with terminal flower (ttaa), we need to understand the principles of Mendelian genetics.
Mendelian genetics states that inheritance is controlled by factors (genes) that come in pairs, one from each parent. These factors can exist in different forms called alleles, which determine the expression of specific traits.
In this case, the gene responsible for plant height has two alleles: "T" for tall and "t" for dwarf. The gene responsible for flower position has two alleles: "A" for axial and "a" for terminal.
The homozygous tall plant with axial flowers (TTAA) has two copies of the dominant alleles, "T" and "A." The homozygous dwarf plant with terminal flowers (ttaa) has two copies of the recessive alleles, "t" and "a."
To determine the phenotype ratio of the F1 generation:
1. We cross the two parental plants (TTAA x ttaa).
2. The gametes produced by the homozygous tall plant are TA, and the gametes produced by the homozygous dwarf plant are ta.
3. Combine the gametes to form the F1 generation: TtAa.
The F1 generation will have the genotype TtAa. In terms of the phenotype, the dominant alleles ("T" and "A") will be expressed, resulting in tall plants with axial flowers. Therefore, the phenotype ratio of the F1 generation is 100% tall with axial flowers.
To determine the genotype ratio of the F2 generation:
1. We self-cross the F1 generation plants (TtAa x TtAa).
2. The possible gametes produced by the F1 generation are TA, Ta, tA, and ta.
3. Combine the gametes to form the F2 generation: TTAA, TTAa, TtAA, TtAa, TTAa, Ttaa, ttAA, ttAa, Ttaa, and ttaa.
Counting the different genotypes in the F2 generation, we have:
- TTAA: 1
- TTAa: 2
- TtAA: 2
- TtAa: 4
- ttAA: 1
- ttAa: 2
- Ttaa: 2
- ttaa: 1
Therefore, the genotype ratio of the F2 generation is:
TTAA: 1:16
TTAa: 2:16
TtAA: 2:16
TtAa: 4:16
ttAA: 1:16
ttAa: 2:16
Ttaa: 2:16
ttaa: 1:16