Final answer:
In a sexually-reproducing organism with 6 chromosomes at generation 0, under the process of meiosis and subsequent fertilization, the number of chromosomes will remain 6 in generation 4. Meiosis halves the chromosome number in gametes, and fertilization restores it, ensuring a consistent chromosome number across generations.
Step-by-step explanation:
The question revolves around the number of chromosomes present in a sexually-reproducing organism across generations under the typical model of meiosis. Meiosis is a form of cell division that reduces the chromosome number by half to produce haploid gametes, ensuring that when fertilization occurs, the resulting zygote has the correct number of chromosomes. Therefore, regardless of the number of generations, the number of chromosomes stays consistent as meiosis and fertilization cycle through each generation.
In generation 0, if the organism starts with 6 chromosomes, each gamete after meiosis will have 3 chromosomes (haploid). After fertilization, the resulting zygote will also have 6 chromosomes, restoring the diploid state. This cycle repeats itself in each generation, maintaining the chromosome number at 6. Thus, in generation 4, the organism would still have 6 chromosomes.