What term refers to a condition where an organism has three sets of chromosomes?

The term that refers to a condition in which an organism has three sets of chromosomes is triploidy. In a triploid organism, there are three complete sets of chromosomes instead of the usual two sets that occur in diploid organisms. This condition can occur in various species and is particularly noted in some plants and a few animal species.

Triploidy can result from errors during cell division, such as failure of the chromosomes to separate properly during meiosis, leading to gametes that have an abnormal number of chromosomes. When two such gametes come together during fertilization, the resulting zygote ends up with three sets of chromosomes.

Understanding triploidy is essential in genetics as it can lead to unique characteristics in the organism, and in many cases, triploid organisms may have reduced fertility or may be sterile. This condition is an important topic in the study of genetic variations and chromosomal abnormalities.