A geneticist examines the karyotype of a diploid cell from a particular species of frog and determines that 12 chromosomes are present. If a germ-line cell from this species divides by meiosis, then at the end of meiosis I each cell will have

6 chromosomes each

Explanation:

Meiosis is the cell division that results in daughter cells with a reduced number of chromosomes (by half). Meiosis is used only by sexually-reproducing organisms to produce gametes. Since meiosis reduces the chromosomal number, it occurs in a two-step division process viz: Meiosis I and Meiosis II.

Meiosis I involves separation of homologous chromosomes (similar but non-identical chromosomes received from each parent). In the Anaphase stage of meiosis 1, each homologous pair of chromosomes that makes the organism diploid (2n) is separated. Hence, the resulting cells of meiosis I will have a reduced chromosome number (haploid, n).

In this case of a diploid frog with 12 number of chromosomes. If a germline cell or reproductive cell divide by meiosis, in meiosis I, each pair of the 6 pairs of homologous chromosomes of the frog will separate into opposite cells. Hence, at the end of meiosis I, each daughter cell will have 6 chromosomes in a haploid state.

In meiosis II, sister chromatids (replicated chromosomes) separate instead. Each separated chromatid becomes a full chromosome in each gamete.