Final answer:
Polyploidy is the condition in which an organism has more than the normal number of chromosome sets. It can be found in animals and plants.
Step-by-step explanation:
An individual with more than the correct number of chromosome sets (two for diploid species) is called polyploid. For example, fertilization of an abnormal diploid egg with a normal haploid sperm would yield a triploid zygote. Polyploid animals are extremely rare, with only a few examples among the flatworms, crustaceans, amphibians, fish, and lizards. Polyploid animals are sterile because meiosis cannot proceed normally with an odd number of chromosome sets. In contrast, polyploidy is very common in the plant kingdom, and polyploid plants tend to be larger and more robust than euploids of their species.