In a different species of plant, bell shaped flower is dominant to tube shaped flower and the gene controlling this trait is inherited in normal Mendelian fashion. Flower colour can be either red, white, or in combination pink. The two genes are not linked.
Give a reasoned explanation along with the use of full genetic diagrams to proof your answer, to explain in terms of the simultaneous transmission of characteristics, the possible outcomes of crossing a heterozygous bell flowered plant with pink flowers, and a tube flowered plant with white flowers. You should also clearly identify the phenotypic combinations that are not possible from this cross.
Assuming the flower form gene's dominant (bell shape) and recessive (tube shape) alleles, respectively, 'Y' and 'y'. Depending on the assignment, Y absolutely dominates y. Suppose the flower color gene's dominant (red color) and recessive (white color) alleles, respectively, 'R' and 'r'. According to the assignment, R incompletely dominates r, so the Rr combination leads to the pink color of flowers. R is dominant with r when they instead code proteins that are involved in pigment synthesis if they describe color. The lack of pigment stimulates the flower's white color. Instead, the loss of pigment is attributable to transcription of the defective gene product (in that case, r allele). Although if the functional product were coded by at least one allele (in that case R), the flower will have pigment and so would not have a recessive feature. The phenotypic variations that can not be made from this cross are cone- or bell-shaped red flowers. Only a combination of two R alleles will achieve the red color, but it is unlikely since one of the parents loses the R allele.
Possible effects by crossing pink flowers with a heterozygous bell-flowered plant and white flowers with a tube-flowered plant: pink flowers bell-shaped, white flowers bell-shaped, pink flowers tube-shaped, white flowers tube-shaped. The phenotypic variations that can not be made from this cross are cone- or bell-shaped red flowers.