During meiosis i, assuming no crossing over, what chromatid combination(s) will be present at the completion of prophase i?

Answer

         Crossing over is the phenomenon in which exchange of chromtids occur between non sister chromatids  and result into recombinant chromatids, which is an important tool for evolution and bring about genetic changes in offsprings as compare to their parents.

No crossing over

                If no crossing over occurs, it means no exchange of chromatids between non sister chromatids of homologous chromosomes, then no recombinant chromatids will be formed.

Result

        At the end of meiosis II, when four haploid cells are formed, all these cell will contain similar chromosomes as present in parent. Thus chromosomes are non recombinant because of no crossing over.