Mark the incorrect statement w.r.t law of segregation

Options

A. Each gamete contains only one allele for a gene
B. The two alleles present in the F_1 generation segregate during random fusion of gametes, thus giving 3 : 1 ratio
C. Each gamete is always pure for its/a trait
D. The recessive trait which is not observed in the F_1 generation reappears in F_2 generation

Answer

To solve the question regarding the incorrect statement with respect to the law of segregation, we will analyze each of the provided statements one by one.

### Step-by-Step Solution:

1. **Understanding the Law of Segregation**:
- The law of segregation states that during the formation of gametes, the two alleles for a trait separate from each other. Each gamete will carry only one allele for each gene.

2. **Analyzing Each Statement**:
- **Statement A**: "Each gamete contains only one allele for each gene."
- This statement is **correct** as per the law of segregation.

- **Statement B**: "The two alleles present in F1 generation segregate during random fusion of gametes thus giving a 3:1 ratio."
- This statement is also **correct**. The segregation of alleles leads to a phenotypic ratio of 3:1 in the F2 generation when crossing heterozygous individuals.

- **Statement C**: "Each gamete is always pure for its trait."
- This statement is **correct** because, according to the law of segregation, each gamete carries only one allele, making it pure for that trait.

- **Statement D**: "The recessive trait which is not observed in F1 generation reappears in F2 generation."
- This statement is **incorrect** in the context of the law of segregation. While recessive traits do reappear in the F2 generation, they are not completely absent in the F1 generation. In a typical monohybrid cross, the recessive trait is masked by the dominant trait in the F1 generation but is still present in the genotype.

3. **Conclusion**:
- The incorrect statement with respect to the law of segregation is **Statement D**.

### Final Answer:
**The incorrect statement is: "The recessive trait which is not observed in F1 generation reappears in F2 generation." (Option D)**

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