Final answer:
Polyploidy is a chromosome mutation characterized by the addition of one or more sets of chromosomes, often resulting in larger and more robust plant individuals compared to their normal counterparts. It is distinct from aneuploidy or other structural chromosome mutations such as inversions.
Step-by-step explanation:
The type of chromosome mutation in which one or more sets of chromosomes are added is known as polyploidy. This condition leads to an individual acquiring more than the typical number of chromosome sets. For example, should an abnormal diploid egg become fertilized by a normal haploid sperm, it could result in a triploid zygote which is a form of polyploidy. Another relevant term is autopolyploidy, which refers to an individual that has two or more complete sets of chromosomes from its own species due to an error in meiosis where all chromosomes end up in one cell. Polyploidy is fairly common in plants and these plants usually exhibit increased size and robustness compared to their diploid counterparts.