1.A white flowered plants is crossed with a plant that is heterozygous for the trait. What percentage of he offspring will have purple flowers?
2.Two plants, both heterozygous for he gene that controls flower color are crossed. What percentage of their offspring will have purple flowers? What percentage will have white flowers?
25%
1 out of 4 chance
To answer both questions, we need to understand the principles of Mendelian genetics and the inheritance patterns of flower color.
1. In the first scenario, let's represent "W" as the dominant allele for white flowers and "w" as the recessive allele for purple flowers. The plant with white flowers is crossed with a plant that is heterozygous for the trait, which means it carries both the dominant and recessive alleles (Ww). Since the white-flowered plant is homozygous for the recessive allele (ww), all of its gametes will carry the recessive allele.
When these two plants are crossed, the possible genotypes of the offspring are: Ww and ww. The plants with the genotype Ww will display the white phenotype because the dominant allele masks the recessive allele, giving them white flowers. The plants with the genotype ww will have purple flowers since they lack the dominant allele to mask the expression of the recessive allele. Therefore, 50% of the offspring will have purple flowers and 50% will have white flowers.
2. In the second scenario, both plants are heterozygous for the flower color gene (Ww x Ww). The possible genotypes of the offspring are: WW, Ww, and ww. Again, the plants with the genotype WW and Ww will express the white phenotype, and those with the genotype ww will exhibit the purple phenotype. So, 75% of the offspring will have white flowers (WW and Ww) and 25% will have purple flowers (ww).
In Mendelian genetics, the percentage of offspring with a specific phenotype or genotype can be determined by understanding the inheritance patterns and the probability of different genotypes being produced through genetic crosses.