Question

In a different species of plant, narrow leaf is dominant to broad leaf, and flower color can be either red, blue, or in combination purple. The two genes are not linked. Give a reasoned explanation along with the use of full genetic diagrams to prove your answer, to explain in terms of the simultaneous transmission of characteristics, the possible outcome of crossing a heterozygous narrow leaf plant with blue flowers and a broad leaf plant with purple flowers.

a) The outcome will be all narrow leaf plants with red flowers.
b) The outcome will be a mix of narrow and broad leaf plants with blue and purple flowers.
c) The outcome will be all broad leaf plants with purple flowers.
d) The outcome cannot be determined.

Answer 1

The outcome will be a mix of narrow and broad leaf plants with blue and purple flowers. Two separate Punnett squares for leaf width and flower color show the combination of traits will lead to a variety of plant phenotypes within the offspring.

Step-by-step explanation:

We are considering a cross between a heterozygous narrow leaf plant with blue flowers and a broad leaf plant with purple flowers. Let's designate narrow leaf as the dominant trait (N) and broad leaf as the recessive trait (n). For the flower color, blue (B) and red (R) are co-dominant alleles which produce purple (BR) when combined. The heterozygous narrow leaf, blue flowered plant can have genotypes NnBB, and the broad leaf, purple flowered plant with genotype nnBR.

Using a Punnett square for leaf width, the possible genotypes for the offspring are Nn and nn, meaning the offspring will be a mix of narrow (Nn) and broad leaf (nn) plants. Using a separate Punnett square for the flower color, the genotypes are BB, BR, and RB. This will result in a mix of blue (BB) and purple (BR, RB) flowers.

Therefore, the outcome of the cross will not produce uniform offspring but a mix of phenotypes for both leaf width and flower color.