Question

1. two parent plants are crossed. parent 1 has the genotype anl/anl, ygr/ygr. parent 2 has the genotype anl/anl, ygr/ygr the punnett square for the cross is shown below. about what percentage of the offspring plants will have purple stems and green leaves?

parent 1: anl/anl, ygr/ygr
parent 2: anl/anl, ygr/ygr
100%
75%
25%
0%

Explanation:

Step1: Determine the alleles for purple stems

Purple stems are determined by the \(ANL\) allele. Parent 1 has genotype \(anl/anl\) (no \(ANL\) allele for purple stems). Parent 2 has genotype \(ANL/anl\). When crossed, the possible combinations for the stem - related allele:
From Parent 1: \(anl\)
From Parent 2: \(ANL\) or \(anl\)
The combinations are \(ANL/anl\) (purple) and \(anl/anl\) (not purple). But for the offspring to have purple stems, they need at least one \(ANL\) allele. However, looking at the cross:
Parent 1 can only give \(anl\) for the stem - related gene (since it is \(anl/anl\)). Parent 2 can give \(ANL\) or \(anl\). But when we consider the cross in terms of the Punnett square (assuming a dihybrid - like cross, but focusing on the stem - related gene first). Since Parent 1 is \(anl/anl\) (homozygous recessive for the stem - related gene), and we are looking for purple stems (\(ANL\) - containing genotype). The \(ANL\) allele is dominant. But Parent 1 cannot contribute an \(ANL\) allele.

Step2: Analyze the leaf - related gene

For green leaves, assume \(YGR\) is the allele for green leaves. Parent 1 is \(YGR/ygr\) (heterozygous) and Parent 2 is \(ygr/ygr\) (homozygous recessive). The possible leaf - related genotypes of offspring: \(YGR/ygr\) (green) and \(ygr/ygr\) (not green). But since we already saw from the stem - related gene analysis that Parent 1 (\(anl/anl\)) cannot contribute to the purple - stem genotype (because purple stems need \(ANL\) and Parent 1 has no \(ANL\) alleles).

Answer:

D. 0%