The tortoise beetle, Chelymorpha alternans, is an insect found in Panama that has several different colour patterns. [Figure 3.1] Researchers have identified a gene, L, that controls colour pattern in the pronotum and elytra. Gene L has four different alleles: LV, LT, LR and Lr. [Table 3.1] shows five different colour pattern phenotypes of tortoise beetles and their genotypes.

1. (a)Explain why the inheritance of colour pattern in tortoise beetles can be described as involving multiple alleles.[1]
2. (b)A tortoise beetle with dfm-b phenotype was crossed with another tortoise beetle with dfm-b phenotype. Construct a genetic diagram to show the results of this cross, including the ratio of offspring phenotypes. parental phenotypes: dfm-b x dfm-b parental genotypes: gametes: offspring genotypes: offspring phenotypes: ratio of offspring phenotypes:[4]
3. (c)Colour pattern phenotype involves alleles that show codominance. There is also an order of dominance of alleles (dominance hierarchy). Use the information in Table 3.1 to: • identify the codominant alleles • list the dominance hierarchy with alleles from the most dominant to the least dominant. codominant alleles dominance hierarchy[2]
4. (d)Researchers carried out two crosses. Cross 1: female veraguensis tortoise beetles were crossed with male metallic tortoise beetles. The results are shown in [Table 3.2]. Cross 2: female veraguensis tortoise beetles were crossed with male veraguensis tortoise beetles. The results are shown in [Table 3.3].
5. (d)(i)Using Table 3.1, deduce the genotypes of each of the parental beetles used in cross 1 and cross 2. cross 1 cross 2[2]
6. (d)(ii)An assumption was made that female tortoise beetles have XX chromosomes and males have XY chromosomes. Gene L is not located on the X chromosome. It was concluded that colour pattern phenotype followed autosomal inheritance. Explain how the evidence in Table 3.3 supports this conclusion.[1]
7. (d)(iii)Name a statistical test that can be used to determine whether the ratio of observed phenotypes is significantly different from the expected ratio.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.