Table 3.

Categories of explanations from students’ final research posters associated with the influence of genotypic variation (Gv) and environmental variation (Ev) on variation of the anthocyanin intensity phenotype^a

Explanation	Level	Example quotations from student final research posters.
Influence of genotypic variation (Gv)	High	“Anthocyanin is produced through the flavonoid biosynthesis pathway, which involves many gene loci suggesting that intensity of pigment is a quantitative trait. Plants with more intensely purple stems contain a higher proportion of alleles for high anthocyanin production and selection can increase these allelic frequencies in offspring.”
	Intermediate	“Intensity of anthocyanin pigmentation is controlled by multiple genes [coding for] biochemical intermediates, and it is heritable as a quantitative trait. Offspring show similar phenotypes [to] their parents in a common environment through artificial selection.”
	Low	“Anthocyanin is a quantitative trait where each gene involved in the biochemical pathway contributes a ‘dose’ of anthocyanin. When many genes influence a phenotype like anthocyanin in B. rapa, selection for purple genes creates purple offspring.”
		“[Anthocyanin is] influenced by number of doses of dominant alleles. If Fl is bred for the ANL allele, then offspring will have an increase in ANL alleles (F2s).”
Influence of environmental variation (Ev)	High	“Exposure to increased UVB [light] up regulates gene expression to aid in anthocyanin production.… significantly greater increase in F2s [pigmentation] as compared with F2d in UVB treatments was most likely due to F2s populations having a greater potential for expression due to selection in Fl for higher expressing alleles.”
	Intermediate	“Sucrose is the major form of soluble C for long-distance transport in plants. [Sucrose is] shown to up regulate anthocyanin-related genes by acting as a signal molecule and creating a C-surplus environment, stimulating Shikimate pathway to produce anthocyanin.”
	Low	“B. rapa has strong expression of anthocyanin in abundant light; anthocyanin production is less intense in reduced light. Ornamental grasses (similar to B. rapa) are purple in abundant light and pale violet/green in low-light environments.”

^aExample quotations of student explanations from final research posters are separated by level as high, intermediate, or low based on rubric coding schema.