Question

1. zebra mussel genetics

zebra mussels are an invasive species to russia in the mid-1980s, zebra mussels were introduced into the great lakes region of the united states where they rapidly reproduced. females can produce up to one million eggs per year. in one zebra mussel population, most of the individuals have dark, zebra - striped shells (genotype aa). however, solid light - colored shells (genotype aa) occur in 1 of every 10,000 individuals. the solid light - colored shells indicate mussels that are not hardy in cold water temperatures (<15°c). heterozygous individuals (aa) have solid, dark - colored shells.
which cross would produce the greatest genetic diversity among the offspring?
a aa × aa
b aa × aa
c aa × aa
d aa × aa

Explanation:

Step1: Analyze each cross

• Cross A (AA × aa): Offspring will all be Aa (100% Aa).
• Cross B (AA × Aa): Offspring genotypes: AA (50%) and Aa (50%).
• Cross C (aa × Aa): Offspring genotypes: Aa (50%) and aa (50%).
• Cross D (Aa × Aa): Offspring genotypes: AA (25%), Aa (50%), aa (25%).

Step2: Determine genetic diversity

Genetic diversity is related to the number of different genotypes. Cross D produces three genotypes (AA, Aa, aa), while others produce fewer. So Cross D has the greatest genetic diversity.

Answer:

D. Aa × Aa