Final answer:
An organism with three sets of chromosomes is called a triploid, and an organism with four sets of chromosomes is called a tetraploid. Polyploidy can cause issues in meiosis for animals but can result in larger, more robust plants.
Step-by-step explanation:
An organism that has three sets of chromosomes is called a triploid, while one with four sets is called a tetraploid.
Most animals and plants are diploid, meaning they have two sets of chromosomes in their somatic cells. Polyploidy refers to the condition of having more than two sets of chromosomes.
Polyploid organisms can have issues with meiosis, the process of sexual cell division, which can lead to sterility, especially in triploid animals. In contrast, polyploid plants are common and can be larger and more robust than their diploid counterparts.