A cross between true breeding tall red flowered plants and true breeding short white flowered plants. Tall and red are dominant traits. What would be the expected ratios of phenotypes in the f1 and f2 generations? what is the exoected ohenityouc ratui if F2 ganeration if red and white are codominant?
Work out the punnett squares, compute the ratios. We can critique your work.
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I don't know how though
See your text on punnett squares, or
http://www.athro.com/evo/gen/punexam.html
1:2:1
To determine the expected ratios of phenotypes in the F1 and F2 generations, we can use Punnett squares. Punnett squares are a visual tool used to understand the genetic outcomes of a cross between two individuals.
In this scenario, we have a cross between true breeding tall red-flowered plants (RR) and true breeding short white-flowered plants (rr). The tall and red traits are dominant, while the short and white traits are recessive.
1. F1 Generation:
To determine the phenotypes of the F1 generation, we need to create a Punnett square by crossing one parent with two alleles for tall and red (RR) with another parent with two alleles for short and white (rr).
Punnett square:
| R | R |
-----------------
r | Rr | Rr |
From the Punnett square, we can see that all offspring in the F1 generation (100%) will have the genotype Rr, which represents the tall and red phenotype.
2. F2 Generation:
To determine the phenotypes of the F2 generation, we will need to cross the F1 generation individuals with each other. Remember that the F1 generation plants have the genotype Rr.
Punnett square:
| R | r |
----------------
R | RR | Rr |
r | Rr | rr |
From the Punnett square, we can see that the phenotypic ratio in the F2 generation will be 3:1. This means that approximately 75% of the offspring will exhibit the tall and red phenotype (either RR or Rr), while about 25% will have the short and white phenotype (rr).
Now, if red and white are codominant traits, it means that the heterozygotes (Rr) will exhibit a third phenotype of having both red and white flowers.
Punnett square for codominant traits:
| R | r |
----------------
R | RR | Rr |
r | Rr | rr |
In this scenario, the phenotypic ratio in the F2 generation would be 1:2:1. This means that approximately 25% of the offspring will have the tall and red phenotype (RR), 50% will have the heterozygous phenotype with both red and white flowers (Rr), and the remaining 25% will have the short and white phenotype (rr).
Remember to always consult additional resources, such as the Punnett square example you provided, to validate your work and ensure accuracy.