A test cross of AaBb to aabb gives 950 parental and 50 nonparental offspring. What is the recombination frequency?

1. Add the classes to get the total progeny: 950 plus 50 gives 1000. 2. The nonparental offspring are the recombinants, since they carry new allele combinations. 3. There are 50 of them, arising as Aabb or aaBb. 4. Recombination frequency is recombinants divided by total, so 50 divided by 1000. 5. That gives 0.05, which is 5 percent. 6. Such a result shows the genes are definitely linked, since 0.50 would mean no linkage at all. 7. They are nevertheless far enough apart for crossovers to occur occasionally. 8. The value 0.95 is the parental fraction, which is the complement rather than the answer. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 13 "Modern Understandings of Inheritance", section 13.1 Chromosomal Theory and Genetic Linkage_