Mendel found that flower color in certain pea plants obeyed the following scheme.
Pure red crossed with pure white produces red.
When pure red (RR) and pure white (rr) parents are crossed, the resulting Rr combination (one of each gene) produces second generation offspring with red flowers, since red is dominant. Suppose one of these second generation Rr flowers is crossed with a pure red. What is the probability that the resulting plant will have red flowers?
To determine the probability of the resulting plant having red flowers, we need to understand the principles of Mendelian inheritance and the genotype of the parent plants.
In Mendel's experiments, he observed that certain traits in pea plants are inherited according to specific patterns. One of the basic principles he discovered is the Law of Dominance, where one gene (allele) can be dominant over another. In this case, the red color allele (R) is dominant over the white color allele (r).
From the given information, we know that the parent plants being crossed are a pure red (RR) and a pure white (rr). When these parents are crossed, their offspring all carry one red allele and one white allele, making them heterozygous for flower color (Rr). Since red is dominant, all of the second-generation offspring have red flowers.
Now, we are asked about the probability of a resulting plant having red flowers when one of these second-generation Rr flowers is crossed with a pure red plant.
To determine the probability, we need to consider the possible combinations of alleles in the second-generation Rr plant. Let's denote the R allele from the second-generation plant as R' to distinguish it from the pure red parent's R allele.
When the second-generation Rr plant (R'r) is crossed with a pure red plant (RR), we can consider the possible combinations of alleles in the offspring:
1) The second-generation plant passes on its R' allele, and the pure red plant passes on its R allele. This results in offspring with the genotype R'R, which will have red flowers.
2) The second-generation plant passes on its R' allele, but the pure red plant passes on its other R allele. This results in offspring with the genotype R'r, which will also have red flowers.
Thus, both possible combinations will result in plants with red flowers.
Therefore, the probability that the resulting plant will have red flowers is 100% or 1.