phenotypic and genotypic ratios are equal in

Options

A. incomplete dominance
B. Test cross
C. All monohybrid crosses
D. Both (1)&(2)

Answer

To solve the question regarding when phenotypic and genotypic ratios are equal, we can follow these steps:

### Step 1: Understand the Definitions
- **Phenotypic Ratio**: This is the ratio of different phenotypes (observable traits) in the offspring.
- **Genotypic Ratio**: This is the ratio of different genotypes (genetic makeup) in the offspring.

**Hint**: Remember that phenotypes are what you see, while genotypes are what you get from the genes.

### Step 2: Identify Situations Where Ratios are Equal
- The question asks in which genetic scenarios the phenotypic and genotypic ratios are the same.

**Hint**: Think about genetic crosses that produce a mix of traits.

### Step 3: Analyze Incomplete Dominance
- In incomplete dominance, when a red flower (RR) is crossed with a white flower (rr), the offspring (Rr) will be pink. The phenotypic ratio is 1 red: 2 pink: 1 white, and the genotypic ratio is also 1 RR: 2 Rr: 1 rr. Here, both ratios are 1:2:1.

**Hint**: Incomplete dominance shows a blending of traits.

### Step 4: Analyze Test Cross
- A test cross involves crossing an individual with an unknown genotype with a homozygous recessive individual. If the unknown is homozygous dominant, the offspring will show a 1:1 ratio. If the unknown is heterozygous, the offspring will show a 1:1 ratio as well.

**Hint**: Test crosses help reveal hidden genotypes.

### Step 5: Compare with Monohybrid Cross
- In a typical monohybrid cross (e.g., tall vs. dwarf plants), the phenotypic ratio is 3:1 (3 tall: 1 dwarf), while the genotypic ratio is 1:2:1 (1 homozygous dominant: 2 heterozygous: 1 homozygous recessive). Here, the ratios are not equal.

**Hint**: Monohybrid crosses often show different ratios for phenotype and genotype.

### Step 6: Conclusion
- The scenarios where the phenotypic and genotypic ratios are equal are **incomplete dominance** and **test crosses**. Therefore, the correct answer is that they are equal in both situations.

**Final Answer**: Phenotypic and genotypic ratios are equal in **incomplete dominance** and **test crosses**.