Question

A heterozygous orange-flowered plant is crossed with a homozygous purple-flowered plant. If orange is a dominant allele and purple is recessive, what color ratio will the flowers of the offspring plants have?

Answer 1

In this scenario, we have two plants: one heterozygous orange-flowered (let's denote the alleles as \( O \) for orange and \( o \) for purple) and one homozygous purple-flowered (which has the genotype \( oo \)).

The genotypes of the plants are:
- Heterozygous orange-flowered plant: \( Oo \)
- Homozygous purple-flowered plant: \( oo \)

To determine the color ratio of the offspring, we can use a Punnett square to predict the possible genotypes resulting from this cross.

### Punnett Square Setup:
| | \( o \) | \( o \) |
|-------|---------|---------|
| \( O \) | \( Oo \) | \( Oo \) |
| \( o \) | \( oo \) | \( oo \) |

### Offspring Genotypes:
1. \( Oo \) - orange-flowered (dominant)
2. \( oo \) - purple-flowered (recessive)

### Ratio of Flower Colors:
From the Punnett square, we see that:
- 2 out of 4 offspring (or 50%) will have the genotype \( Oo \) (orange-flowered).
- 2 out of 4 offspring (or 50%) will have the genotype \( oo \) (purple-flowered).

Thus, the color ratio of the flowers in the offspring will be:
- **1 orange-flowered : 1 purple-flowered** or **50% orange : 50% purple**.

In simplified terms, the ratio is **1:1**.