A plant with red flowers is crossed with a white-flowered plant. All the seeds produce plants with red flowers. The flower colour is controlled by a single pair of alleles, which allele is dominant and which is recessive?

ANSWER: The allele for red-coloured flowers must be dominant if no white flowers appear in the first generation.EXPLANATION:First, let’s go through some definitions:Dominant Allele: an allele that produces the same phenotype whether its paired allele is identical or differentRecessive Allele: an allele that produces its characteristic phenotype only when its paired allele is identicalHomozygous: a particular gene that has identical alleles on both homologous chromosomes. It can be represented by two capital letters (XX) for a dominant trait, and two lowercase letters (xx) for a recessive traitHeterozygous: a particular gene that has different alleles on both homologous chromosomes. It can be represented in this (Xx) form.So let’s assume that the genotype of the red flowers is homozygous dominant and the genotype of the white flowers was homozygous recessive.Parental Genotypes:Red Flower: RRWhite Flower: rrWhen we draw out a punnet diagram to determine the phenotype of the offspring, we get this:(I would proceed to use the whiteboard)1^st Generation Offspring Genotype:Rr (100%)1^st Generation Offspring Phenotype:Red