The document discusses euploidy, or changes in the number of sets of chromosomes, in animals and plants. It notes that while most animal species are diploid, some natural variations exist, including polyploidy in certain tissues and endopolyploidy. Polyploidy is more common and tolerated in plants, with 30-35% of ferns and flowering plants being polyploid. Examples are given of polyploid crops like wheat, cotton, and strawberries that are important agricultural products.