Suppose you have monohybrid snapdragons in your garden and you find that they produce red seeds to white seeds in the ratio of 3:1. If the alleles are designated R (red seeds) and r (white seeds), what are the probable phenotypes of the parents (P1)?
Rr for both. Check with Punnett square.
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Suppose you have monohybrid snapdragons in your garden and you find that they produce red seeds to white seeds in the ratio of 3:1. If the alleles are designated R (red seeds) and r (white seeds), what are the probable genotypes of the snapdragons in your garden?
To determine the probable phenotypes of the parents (P1) in a monohybrid cross, we can use the observed ratio of red to white seeds in the offspring. In this case, the ratio is 3:1, meaning that for every 3 seeds with red alleles (RR or Rr), there is 1 seed with white alleles (rr).
From this information, we can make the following conclusions:
1. The ratio of red to white seeds suggests that one of the parents must have had two red alleles (RR), as one red allele from each parent is needed to produce red seeds.
2. The other parent must have had at least one white allele (rr), as they would contribute one white allele to the offspring.
Therefore, the probable phenotypes of the parents (P1) can be inferred as follows:
- The genotype of one parent is probably RR (two red alleles), meaning this parent has the phenotype of producing red seeds.
- The genotype of the other parent is probably Rr or rr (at least one white allele), meaning this parent has the phenotype of producing either red or white seeds.
To determine the probable phenotypes of the parents (P1) in this monohybrid cross, we can use the information provided about the ratio of red seeds to white seeds produced.
In this case, the ratio of red seeds to white seeds is given as 3:1. This tells us that for every 3 red seeds produced, there is 1 white seed. Since red seeds are designated by the dominant allele (R) and white seeds by the recessive allele (r), we can infer that the phenotype ratio in this case is also 3:1.
Let's consider the possible genotypes and phenotypes of the parents:
- The genotype of the first parent could be either RR or Rr. If it is RR, then all of its gametes will contain the dominant allele (R). If it is Rr, half of its gametes will contain the dominant allele (R), and the other half will contain the recessive allele (r).
- The genotype of the second parent must be rr since it produces only white seeds. All of its gametes will contain the recessive allele (r).
Combining the possible genotypes of both parents, we have two potential crosses:
1. RR x rr
- The first parent (RR) will produce only gametes with the R allele.
- The second parent (rr) will produce only gametes with the r allele.
- The offspring will inherit one allele from each parent, resulting in all Rr individuals (red phenotype).
2. Rr x rr
- The first parent (Rr) will produce half of its gametes with the R allele and the other half with the r allele.
- The second parent (rr) will produce only gametes with the r allele.
- The offspring will inherit one allele from each parent. This will result in 50% being Rr (red phenotype) and 50% being rr (white phenotype).
Therefore, the probable phenotypes of the parents (P1) are either RR or Rr, depending on whether there is a homozygous dominant individual (RR) or a heterozygous individual (Rr) in the mix.