TABLE 4.

Application of the DNA triangle to passages from introductory and middle/upper-level biology textbook passages

	Molecular	Chromosomal	Informational
Ploidy	Not found in any of the textbooks analyzed	The number of chromosome sets is termed the cell’s ploidy. Diploid cells or species are designated 2n, because two chromosomes of each type are present (Freeman et al., 2016).	Organisms can carry one or more copies of the individual genes. For example, yeast can survive indefinitely as a haploid organism, carrying a single copy of its genomes (Craig et al., 2010).
Homology	At the molecular level how, similar are homologous chromosomes? The answer is that the sequence of bases of one homolog usually differs by less than 1% compared with the sequence of the other homolog (Brooker, 2012).	The two chromosomes of a pair have the same length, centromere position, and staining pattern: These are called homologous chromosomes (Reece et al., 2013).	For example, if a gene for eye color is situated at a particular locus on a certain chromosome, then the homolog of that chromosome will also have a version of the same gene specifying eye color at the equivalent locus (Reece et al., 2013).
Mechanism of homologous pairing	In many organisms, the initial association—the process of pairing—seems to be mediated by an interaction between matching maternal and paternal DNA sequences at numerous sites that are widely dispersed along the chromosomes (Alberts et al., 2009).	Each pair of duplicated homologs is now held together by at least one chiasma… the connection that corresponds to a crossover between two non-sister chromatids. (Alberts et al., 2009).	Homologous chromosomes continue to condense and undergo synapsis (gene-for-gene pairing) (Morris et al., 2015).