Final answer:
If a germ cell fails to undergo mitosis or meiosis after DNA replication, nondisjunction may lead to gametes with an abnormal chromosome number, affecting offspring. Mutations contribute to genetic diversity but may also cause disorders.
Step-by-step explanation:
If a germ cell fails to undergo mitosis or meiosis after DNA replication, the doubling of the genome may be passed on to gametes and eventually to the progeny. This occurrence is due to nondisjunction, which happens when homologous chromosomes during meiosis I, or sister chromatids during meiosis II, fail to separate. As a result, gametes may contain an abnormal number of chromosomes, leading to genetic disorders in offspring. Alternatively, if mutations after DNA replication are not corrected before cell division, they can contribute to genetic diversity, which is a critical component of evolution. However, significant errors such as nondisjunction can have detrimental effects on the viability and phenotype of an organism.