If the parent or offspring genotypes or phenotypes are known, the pattern of inheritance can be predicted. Two organisms, with genotypes BbDD and BBDd, are mated. Assuming independent assortment of the two loci, which of the following genotypic ratios in offspring would occur?

Question

1BBDD: 1 BbDD: 1 BBDd: 1 BbDd
1 BBDD: 1 bbdd
9 BBDD: 3 BbDD: 3 BBDd: 1 bbdd
1 BBDD: 2 BbDd: 1bbdd

Answer 1

To determine the genotypic ratios of the offspring from the cross between the two organisms with genotypes BbDD (parent 1) and BBDd (parent 2), we can use a Punnett square approach considering the alleles from each parent.

Parent Genotypes:

• Parent 1: BbDD
• Parent 2: BBDd

Alleles Contribution:

• Parent 1 (BbDD) can produce gametes:

  • BD
  • bD

• Parent 2 (BBDd) can produce gametes:

  • BD
  • Bd

Punnett Square:

Now let's fill out the Punnett square with the gametes from each parent:

| | BD | Bd | |--------|-------------|-------------| | BD | BBDD | BBDd | | bD | BbDD | BbDd |

Offspring Genotypes from the Cross:

From the Punnett square:

1. BBDD (from BD and BD)
2. BBDd (from BD and Bd)
3. BbDD (from bD and BD)
4. BbDd (from bD and Bd)

Genotypic Ratios of Offspring:

• 1 BBDD
• 1 BBDd
• 1 BbDD
• 1 BbDd

Thus, the genotypic ratio of the offspring from this cross would be:

• 1 BBDD : 1 BbDD : 1 BBDd : 1 BbDd

This aligns with the first option given:

1 BBDD : 1 BbDD : 1 BBDd : 1 BbDd