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 for a banded shell (b) is dominant over the allele for an unbanded shell (b). the punnett square below shows a cross between two cepaea snails. consider the genotypes of the offspring shown. select all the boxes that represent offspring with a homozygous genotype. b b b bb bb b bb bb

Explanation:

Step1: Define Homozygous

A homozygous genotype has two identical alleles (e.g., \( BB \) or \( bb \), not \( Bb \)).

Step2: Analyze Each Box

• \( BB \): Two \( B \) alleles (homozygous dominant).
• \( Bb \): One \( B \), one \( b \) (heterozygous).
• \( Bb \): One \( B \), one \( b \) (heterozygous).
• \( bb \): Two \( b \) alleles (homozygous recessive).

Step3: Identify Homozygous Boxes

The boxes with \( BB \) and \( bb \) are homozygous.

Answer:

The boxes with \( BB \) (top - left) and \( bb \) (bottom - right) represent offspring with a homozygous genotype.