Final answer:
The number of crossovers present in the food have been found to change the degree of crossing over in animals. Crossing-over occurs during prophase I of meiosis, where there is an exchange of genetic material between non-sister chromatids of homologous chromosomes. This process, also known as recombination, leads to unique combinations of genes and is the first source of genetic variation produced by meiosis.
Step-by-step explanation:
The number of crossovers present in the food have been found to change the degree of crossing over in animals. Crossing-over occurs during prophase I of meiosis, where there is an exchange of genetic material between non-sister chromatids of homologous chromosomes. This process, also known as recombination, leads to unique combinations of genes and is the first source of genetic variation produced by meiosis.