AP BIOLOGY

Detailed explanation-1: -Polyploidy arises as the result of total nondisjunction of chromosomes during mitosis or meiosis. Polyploidy is common among plants and has been, in fact, a major source of speciation in the angiosperms. Particularly important is allopolyploidy, which involves the doubling of chromosomes in a hybrid plant.

Detailed explanation-2: -Polyploidy can occur when an error during meiosis leads to the production of unreduced (i.e., diploid) gametes rather than haploid ones, as shown in Figure 6.1. If two diploid gametes fuse, an autotetraploid will be created whose nucleus contains four copies of each chromosome.

Detailed explanation-3: -Errors can occur during meiosis producing gametes with an extra or missing chromosome. The consequences of this following fertilisation depend on which chromosomes are affected. Often the embryo is not viable, but some of these errors can lead to trisomy conditions or sex chromosome disorders.

Detailed explanation-4: -Polyploid mitotic divisions are error-prone.