Which of the following points further strengthened Mendelism?

Options

A. law of independent assortment which was based on monohybrid
cross
B. law of independent assortment which could be stated on the basis
of segregation of gametes
C. incomplete dominance gave a new way to mendelism
D. a character controlled by a pair of unit factors

Answer

To determine which point further strengthened Mendelism, we need to analyze each of the provided statements about Mendel's laws and their implications. Here’s a step-by-step breakdown:

### Step-by-Step Solution:

1. **Evaluate the First Statement**:
- **Statement**: Law of independent assortment which was based on mono-hybrid cross.
- **Analysis**: This statement is incorrect. The law of independent assortment is actually based on dihybrid crosses, not mono-hybrid crosses. Mendel's first law (law of segregation) pertains to mono-hybrid crosses.

2. **Evaluate the Second Statement**:
- **Statement**: Law of independent assortment could be stated on the basis of segregation of gametes.
- **Analysis**: This statement is also incorrect. The law of independent assortment refers to how different genes independently separate from one another when reproductive cells develop. The segregation of gametes is more closely related to the law of segregation.

3. **Evaluate the Third Statement**:
- **Statement**: Incomplete dominance gave a new way to Mendelism.
- **Analysis**: This statement is incorrect. Incomplete dominance is a form of non-Mendelian inheritance where the phenotype of heterozygotes is intermediate between the phenotypes of the two homozygotes. It does not support Mendel's principles.

4. **Evaluate the Fourth Statement**:
- **Statement**: A character controlled by a pair of unit factors.
- **Analysis**: This statement is correct. Mendel proposed that traits are controlled by pairs of factors (now known as alleles), which is foundational to Mendelian genetics. This directly supports Mendelism.

### Conclusion:
The correct statement that further strengthened Mendelism is: **"A character controlled by a pair of unit factors."**