<span>There are three major groups of mammals, categorized on the basis of their method of reproduction. Monotremes lay eggs to have children instead of having the mother bear them. The second type of mammal is the marsupial, which are non-placental animals who carry their young in their pouches. Eutherians are the third group who are placental mammals.</span>
Answer and Explanation:
Nondisjunction occurs when homologous chromosomes fail to segregate during anaphase I or sister chromatids fail to segregate during anaphase II. The result is an addition or loss of one or more chromosomes. Nondisjunction is associated with disorders like Down's syndrome due to an extra chromosome, Klinefelter's syndrome or Turner's syndrome. These phenomenon where one has three members of homologous chromosome is called trisomy.
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