Question

what step is unique to calculating crossing over in sordaria fungi? dividing by the total number of chromatids matching parental and offspring chromatids counting recombinant chromatids counting parental chromatids

Explanation:

When calculating crossing over in Sordaria fungi, a key step is counting recombinant chromatids. This is because Sordaria has an ordered ascus, and by counting recombinant (non - parental) chromatids (spores in the ascus), we can determine the frequency of crossing over. Dividing by the total number of chromatids is a general step in calculating recombination frequency in many organisms. Matching parental and offspring chromatids is a step in understanding inheritance but not unique to Sordaria. Counting parental chromatids is also a common step in genetic analysis.

Answer:

counting recombinant chromatids