Question

this passage describes the shell banding trait in cepaea snails: cepaea snails live on land in many parts of europe. the shells of cepaea snails can have different colors and patterns. banded shells have dark bands, or stripes, that spiral around their surfaces. unbanded shells do not have bands. in a group of cepaea snails, some individuals have a banded shell and others have an unbanded shell. in this group, the gene for the shell banding trait has two alleles. the allele b is for a banded shell, and the allele b is for an unbanded shell. a certain cepaea snail from this group has a banded shell. this snail has one allele for a banded shell and one allele for an unbanded shell. based on this information, click the blue words to correct any errors in the text. this cepaea snails phenotype for the shell banding trait is an unbanded shell. this cepaea snails genotype for the shell banding gene is bb. this cepaea snail is homozygous for the shell banding gene.

Explanation:

• Phenotype refers to the observable physical or biochemical characteristics of an organism. Since the snail has a banded shell, its phenotype should be a banded shell, not an unbanded shell.
• Genotype \(Bb\) is correct as the snail has one allele for a banded shell (\(B\)) and one allele for an unbanded shell (\(b\)).
• Homozygous means having two identical alleles for a particular gene. Since the snail has two different alleles (\(B\) and \(b\)), it is heterozygous, not homozygous.

Answer:

• Click on “unbanded shell” and change it to “banded shell”.
• Click on “homozygous” and change it to “heterozygous”.