High levels of acid in blood are toxic to cells. Acidic blood or acidosis is toxic to your cells and can reduce their abilities to function properly. When your cells are impaired, they have a hard time fighting bacterias and virus. In addition, they carry less oxygen and cannot effectively utilize nutrients.
Fertilization of the egg by the sperm restores the diploid number of 46 chromosomes. We have 46 chromosomes that, if you lined them up by size and shape (karyotyped them), are actually 23 pairs of chromosomes - one was originally from mom and the other from dear 'ol dad.
Prophase 1 and 2 occur in meiosis which is the process of creating haploid cells. In prophase 1, there are two copies of each chromosome and the cell is said to be diploid (one copy from mum and one copy from dad). The two copies of each chromosome come into contact with each other and swap parts of the chromosome. This introduces genetic diversity.