In which one of the following, complementary gene interaction ratio of 9:7 is observed?

Options

A. Fruit shape in Shepherd's purse
B. Coat colour in mouse
C. Feather colour in fowl
D. Flower colour in pea

Answer

To determine the scenario in which a complementary gene interaction ratio of 9:7 is observed, we can follow these steps:

### Step 1: Understand Complementary Gene Interaction
Complementary gene interaction occurs when two different genes (loci) interact to produce a single phenotype. In this case, both genes must be present in their dominant form to express the dominant phenotype. If either gene is homozygous recessive, the dominant phenotype will not be expressed.

**Hint:** Look for situations where two genes work together to produce a specific trait.

### Step 2: Identify the Ratio
In complementary gene interactions, the typical phenotypic ratio observed in the offspring is 9:7. This means that out of 16 possible combinations, 9 will show one phenotype while 7 will show another phenotype.

**Hint:** Remember that the ratio indicates how many offspring show each phenotype compared to the total.

### Step 3: Analyze the Given Options
The options provided are:
1. Fruit shape of shepherd's purse
2. Coat color in mice
3. Feather color in fowl
4. Flower color in pea

We need to analyze which of these traits is known to exhibit a 9:7 ratio due to complementary gene interaction.

**Hint:** Consider the known genetic studies or examples associated with each option.

### Step 4: Recall Known Examples
From genetic studies, it is known that the flower color in pea plants (Pisum sativum) exhibits a 9:7 ratio due to complementary gene interaction. This occurs when two genes are involved in determining the flower color, and both must be dominant for the purple color to appear.

**Hint:** Think about classic Mendelian genetics and which traits have been extensively studied.

### Step 5: Conclusion
Based on the analysis, the correct answer is that the complementary gene interaction ratio of 9:7 is observed in the flower color of pea plants.

**Final Answer:** Flower color in pea.