Final answer:
A polyploid organism is one with more than two sets of chromosomes. In plants, polyploidy is associated with larger and more robust individuals, while in animals, it is rare and often leads to sterility due to meiosis disruption.
Step-by-step explanation:
Understanding Polyploidy
An organism that contains three or more sets of chromosomes is termed polyploid. This condition contrasts with diploid organisms, which contain two sets of chromosomes, and haploid organisms, which have only one. Polyploidy is rare in animals but quite common in plants where it can result in individuals that are larger and more robust than those with the standard two sets of chromosomes.
In animals, instances of polyploidy can lead to sterility because the presence of an odd number of chromosome sets can disrupt the normal process of meiosis, making sexual reproduction unfeasible. On the other hand, plants do not always face this constraint, and polyploid plants frequently exhibit advantages such as increased size and vigor.