Final answer:
A nullisomic individual of a species with 2n = 22 chromosomes would have 20 chromosomes, due to the loss of a pair of homologous chromosomes resulting in the formula 2n - 2.
Step-by-step explanation:
A nullisomic organism in species III, which has a diploid chromosome number of 2n = 22, would have 20 chromosomes. This occurs because 'nullisomic' refers to the loss of both members of a homologous pair of chromosomes. Normally, a diploid organism has pairs of homologous chromosomes, hence the designation 2n. If one pair is missing entirely, this would result in 2n - 2 chromosomes. Considering there are normally 11 pairs (22 chromosomes) and one pair is missing in a nullisomic individual, only 10 pairs (20 chromosomes) would be present.
This change in chromosome number can affect the viability of the organism. Considering the complexity of genetic information and the mechanisms of inheritance in eukaryotes, a change in chromosome number due to nondisjunction can have significant effects on an organism's survival and development. In species such as humans, the gametes produced through meiosis have immense genetic diversity due to the number of possible chromosome combinations and recombination events. Nonetheless, precise chromosome numbers are crucial for normal development and deviations can lead to conditions like aneuploidy, where there are extra or missing chromosomes.