Law of dominance and recessiveness was the result of

Options

A. Back -cross
B. Incomplete dominance
C. Dihybrid cross
D. Monohybrid cross

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the origin of the law of dominance and recessiveness. This law is fundamental in genetics and explains how certain traits are expressed in offspring.

2. **Identifying Key Terms**: The law of dominance states that in a pair of alleles, one may mask the expression of the other. The dominant allele is expressed, while the recessive allele is not.

3. **Exploring Genetic Crosses**: The question provides options related to different types of genetic crosses: back cross, incomplete dominance, dihybrid cross, and monohybrid cross.

4. **Defining Monohybrid Cross**: A monohybrid cross involves a single trait and examines the inheritance of one pair of contrasting traits. For example, crossing a plant with purple flowers (dominant) with a plant with white flowers (recessive).

5. **Observing the Results**: In a monohybrid cross, the F1 generation will show the dominant trait. When these F1 individuals are crossed, the F2 generation will reveal a 3:1 ratio of dominant to recessive traits, demonstrating the law of dominance.

6. **Conclusion**: The law of dominance and recessiveness is derived from the results of a monohybrid cross, where one allele masks the effect of another.

7. **Final Answer**: Therefore, the law of dominance and recessiveness was the result of a monohybrid cross.

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