If two plants heterozygous for both genes are crossed, what will be the ratio of blue to nonblueflowers?

To solve this genetics problem, we will follow the structured approach:

1. Break Down the Problem

We are crossing two plants that are heterozygous for both genes involved in flower color. Let’s assume:

• The gene for blue flowers (B) is dominant over the gene for non-blue flowers (b).
• Thus, the possible genotypes for the plants are:
  • BB (homozygous blue)
  • Bb (heterozygous blue)
  • bb (homozygous non-blue)

Since both plants are heterozygous (Bb), we can establish a Punnett square to see the outcomes of their cross.

2. Relevant Concepts

Using a Punnett square for a dihybrid cross, we will analyze the combinations of two traits simultaneously. The genotypes of the parents are:

• Parent 1: Bb
• Parent 2: Bb

3. Analysis and Detail

The Punnett square for this cross will look like this:

The results from the Punnett square give us the following genotypes:

• 1 BB (Blue)
• 2 Bb (Blue)
• 1 bb (Non-blue)

Now, to find the ratio of blue to non-blue flowers:

• Total blue flowers = 3 (1 BB + 2 Bb)
• Total non-blue flowers = 1 (1 bb)

4. Verify and Summarize

The final ratio of blue to non-blue flowers is:

• Blue : Non-blue = 3 : 1

Final Answer

The ratio of blue to non-blue flowers is $3:1$.