$ Incomplete dominance is due to gene interaction.
! Complementry genes give the ratio 9:7

Options

A. If both As and R are correct and R is correct explanation of As
B. If both As and R are correct but R is not correct explanation of As
C. If As is correct, R is wrong
D. If both As and R are wrong.

Answer

To solve the question regarding incomplete dominance and complementary genes, we will break it down into steps:

### Step 1: Understand Incomplete Dominance
- Incomplete dominance occurs when neither of the two alleles in a gene pair completely masks the other. Instead, the phenotype of the heterozygote is a blend of the two homozygous phenotypes. For example, if one allele is red (RR) and the other is white (WW), the heterozygote (RW) may appear pink.

**Hint:** Think about how blending colors works; it's similar in genetics.

### Step 2: Define Gene Interaction
- Gene interaction refers to the way in which different genes influence each other's expression. In the case of incomplete dominance, the interaction results in a new phenotype that is distinct from either parent.

**Hint:** Consider how mixing paints creates new colors; genes can "mix" to create new traits.

### Step 3: Understand Complementary Genes
- Complementary genes are pairs of genes that work together to produce a particular phenotype. They are located on different chromosomes and must both have at least one dominant allele present to express a new trait.

**Hint:** Remember that complementary genes need both parts to work, like two halves of a whole.

### Step 4: Recognize the Phenotypic Ratio
- The phenotypic ratio of 9:7 is associated with complementary gene interactions. This means that out of 16 possible combinations of alleles, 9 will show one phenotype while 7 will show another, indicating that both genes are necessary for the expression of the trait.

**Hint:** Ratios in genetics often come from combinations of alleles; visualize a Punnett square.

### Step 5: Analyze the Assertion and Reason
- The assertion states that "incomplete dominance is due to gene interaction," which is correct. The reason given is that "complementary genes give the ratio 9:7," which is also correct. However, the reason does not directly explain the assertion since complementary genes and incomplete dominance are different concepts.

**Hint:** Different concepts can be correct but not necessarily related; think of them as separate facts.

### Step 6: Conclusion
- Since both the assertion and reason are correct, but the reason does not explain the assertion, the answer is that both assertion and reason are correct, but the reason is not the correct explanation of the assertion.

**Final Answer:** Both assertion and reason are correct, but the reason is not the correct explanation of the assertion.