Final Answer:
The primary difference between meiosis I and meiosis II can be identified by the number of chromosomes in the cells and the occurrence of recombination or crossing over.
Step-by-step explanation:
In meiosis I, homologous chromosomes pair up during prophase I and undergo crossing over, leading to genetic recombination. As a result, cells produced after meiosis I contain half the chromosome number but each chromosome consists of two chromatids. This means that cells at the end of meiosis I are haploid but still have duplicated genetic material.
In meiosis II, the sister chromatids separate, similar to mitosis, resulting in cells with half the chromosome number and one chromatid per chromosome. The key distinguishing feature between the two stages lies in the number of chromatids per chromosome. Meiosis II produces cells that are not only haploid but also have a single set of unreplicated chromosomes.
By examining the number of chromosomes and the structure of each chromosome (whether they consist of one or two chromatids), it's possible to differentiate between cells resulting from meiosis I, which are haploid but have duplicated genetic material, and cells from meiosis II, which are haploid and possess unreplicated chromosomes. This distinction allows for the identification of the two stages of meiosis based on the structural characteristics of the cells produced.