How can paternal chromosomes be present in an egg cell during meiosis I or crossing over, if fertilisation has not yet occurred?
when they say paternal chromosome, they mean chromosome of the father of the organism. Not the father of the offspring of the specific organism. During meiosis ,in order to form the gametes, the chromosomes of the mother and the father of a specific organism interact, because homologous chromosome pairs consists of a pair of the organism's fathers chromosomes, and the mother's.
please tell if you still don't get it.