Final answer:
Prophase I is characterized by the pairing of homologous chromosomes and the possibility of crossing-over, while Prophase II involves the preparation of sister chromatids for separation without homologous pairing.
Step-by-step explanation:
The characteristics that distinguish Prophase I from Prophase II in meiosis are primarily related to the behavior of chromosomes. In Prophase I, the most significant event is the pairing of homologous chromosomes, which is unique to this phase.
Homologous chromosomes consist of pairs of chromosomes, one from each parent, that are similar in shape and size and that carry genes controlling the same inherited characteristics.
Additionally, during Prophase I, crossing-over can occur, where homologous chromosomes exchange genetic material, thus increasing genetic diversity.
By contrast, during Prophase II, there are no homologous chromosome pairs to align — instead, the sister chromatids from each chromosome are prepared for separation.
Prophase II mimics Prophase I in terms of the nuclear membrane breaking down and spindle formation, but it lacks the unique pairing and crossing-over of homologous chromosomes.