Mendel also studied the trait of flower color. Some plants had white flowers, while others had purple flowers.
Consider the following cross:
P generation:
Plant with purple flowers= ____
Plant With purple flowers= ____
F1 generation:
75% plant with purple flowers= ____
25% plant with white flowers= ____
Options
Aa
aa
A_
AA
A note on genetic symbols. In some cases, an individual's genotype could be either "AA" or "Aa" and the data provided do not allow you to distinguish between these possibilities. In that case, we will use the shorthand "A_" to represent "AA or Aa".
To determine the possible genotypes of the parent plants in the P generation and the genotypes of the plants in the F1 generation, we can use the principles of Mendelian inheritance.
In this case, we are given that some plants had white flowers (recessive trait) and others had purple flowers (dominant trait). Let's assign the dominant trait as "A" for purple flowers and the recessive trait as "a" for white flowers.
The P generation consists of plants with purple flowers, so the genotype of these plants could be either "A_" (heterozygous) or "AA" (homozygous dominant). Since we don't have enough information to determine if they are heterozygous or homozygous, we can represent the genotype as "A_" (AA or Aa).
Now, let's move on to the F1 generation. We are informed that 75% of the plants have purple flowers and 25% have white flowers. This indicates that the purple flower trait is dominant and the white flower trait is recessive.
In genetics, when individuals with different genotypes for a trait are crossed, the resulting offspring will exhibit a phenotypic ratio that is based on their genotypes.
From the 75% that have purple flowers, we can deduce that their genotype must be at least "A_" (AA or Aa). Since the dominant trait is more common, it is highly likely that these plants are heterozygous (Aa). However, we cannot rule out the possibility of them being homozygous dominant (AA) given the information provided.
Therefore, the correct answer for the F1 generation would be "A_".
From the 25% that have white flowers, we know that their genotype must be homozygous recessive (aa), as the recessive trait only appears when both alleles are present.
Therefore, the correct answer for the 25% plant with white flowers would be "aa".
Hence, the correct options for the P generation are "A_" and "A_" (AA or Aa), and for the F1 generation are "A_" (AA or Aa) and "aa".
Based on the given information, the possible genotypes for the P generation plants with purple flowers are:
Plant with purple flowers = A_
Plant with purple flowers = A_
For the F1 generation, the possible genotypes and phenotypes are:
75% plant with purple flowers = A_
25% plant with white flowers = aa