Question

What would be the number of genotypes and phenotypes, respectively, from a cross between genotypes AaBBCcDd and AaBBCcDd? Assume independent assortment and simple dominant-recessive relationship in each gene pair.

• A. 8 and 4
• B. 12 and 4
• C. 27 and 8
• D. 14 and 8

Hint:

When dealing with multiple gene pairs, remember to use the independent assortment rule to calculate the total number of genotype combinations and phenotypes.

Answer 1

The Correct Option is C

This is a dihybrid cross involving three gene pairs: A/a, B/b, C/c, and D/d. Each gene follows an independent assortment pattern.
- The genotype combinations can be determined using the Punnett square method. For each gene pair, there are two alleles (dominant and recessive), and the combinations for each pair are independent.
- For A/a: 2 possibilities (A or a)
- For B/b: 2 possibilities (B or b)
- For C/c: 2 possibilities (C or c)
- For D/d: 2 possibilities (D or d)
Thus, the total number of genotypes = 2 x 2 x 2 x 2 = 16. However, we must also account for the phenotypes resulting from different allele combinations. There will be 27 possible genotypes, each producing distinct phenotypes based on dominant and recessive traits.
Thus, the correct answer is (C), with 27 genotypes and 8 phenotypes.