Final answer:
Option (1), The configuration of the alleles in the parental double heterozygote is likely in cis configuration, indicated by the high percentage of progeny with parental genotypes and the low percentage with recombinant genotypes, suggesting linked genes with minimal recombination.
Step-by-step explanation:
To determine the configuration of the alleles in the parental double heterozygote based on the progeny percentages given, we need to consider how gene linkage and recombination affect inheritance patterns. Recalling that linked genes tend to be inherited together unless crossing over during meiosis separates them, we can analyze the data provided.
The progeny are:
- 42% TD/td
- 42% td/td
- 8% Td/td
- 8% tD/td
Most of the progeny (84%) exhibit parental genotypes (TD/td and td/td), which indicates linkage between the genes with few recombinants (8% Td/td and 8% tD/td). Based on these percentages, it appears that the alleles are in cis configuration (1), where both dominant alleles (T and D) or both recessive alleles (t and d) are on the same chromosome and tend to be inherited together.
Since the nonparental (recombinant) genotypes are much less frequent, this suggests genes are linked and that crossovers between these genes during meiosis are relatively rare events, leading to a comparatively small proportion of progeny with recombinant genotypes.