In which of the following the ratio of genotypic and phenotypic are same?
a) Co-dominance
b) Incomplete dominance
c) Both of these
d) None of them

Options

A. Co-dominance
B. Incomplete dominance
C. Both of these
D. None of them

Answer

To solve the question regarding the ratio of genotypic and phenotypic expressions in different inheritance patterns, we can break it down into the following steps:

### Step 1: Understand the Concepts of Co-dominance and Incomplete Dominance
- **Co-dominance**: In this type of inheritance, both alleles in a heterozygote are fully expressed, resulting in a phenotype that is neither dominant nor recessive. For example, in blood groups, both A and B antigens can be present in an individual with AB blood type.

- **Incomplete Dominance**: In this case, the heterozygote exhibits a phenotype that is intermediate between the two homozygous phenotypes. For example, crossing a red flower (RR) with a white flower (WW) may produce pink flowers (RW).

### Step 2: Analyze the Genotypic and Phenotypic Ratios
- **Co-dominance**: The genotypic ratio for a typical cross (like IAi x IAi for blood groups) does not equal the phenotypic ratio. For example, the genotypic ratio might be 1:2:1 (IAIA: IAi: ii), while the phenotypic ratio is also 3:1 (A:AB:B). Thus, they are not the same.

- **Incomplete Dominance**: In a typical cross (like RR x WW), the genotypic ratio is 1:2:1 (RR:RW:WW), and the phenotypic ratio is also 1:2:1 (Red:Pink:White). Here, both ratios are indeed the same.

### Step 3: Conclusion
Based on the analysis:
- In **co-dominance**, the genotypic and phenotypic ratios are not the same.
- In **incomplete dominance**, the genotypic and phenotypic ratios are the same.

Thus, the correct answer to the question is **b) Incomplete dominance**.

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