When the inheritance of a character is determined by many genes witht the same but cumulative phenomenon,effect is called quantitative inheritance.

Answer

### Step-by-Step Solution:

1. **Understanding the Concept of Quantitative Inheritance**:
- Quantitative inheritance refers to the inheritance of traits that are controlled by multiple genes (polygenic inheritance) rather than a single gene. These traits exhibit a continuous range of phenotypes rather than discrete categories.

**Hint**: Think about traits that vary in degree rather than being either/or.

2. **Contrast with Mendelian Inheritance**:
- Mendel's laws of inheritance, particularly the Law of Dominance, suggest that traits are determined by single genes with two alleles (dominant and recessive). For example, in pea plants, traits like height are either tall or dwarf, with no intermediate forms.

**Hint**: Recall Mendel's experiments with pea plants and the clear-cut traits he observed.

3. **Polygenic Traits**:
- In quantitative inheritance, many genes contribute to a single trait. For example, human height and skin color are influenced by multiple genes, leading to a range of phenotypes (e.g., various heights and skin tones).

**Hint**: Consider traits in humans that show a spectrum, such as height or skin color.

4. **Cumulative Effect of Alleles**:
- The cumulative effect means that the more dominant alleles present, the more pronounced the trait will be. For instance, in skin color, if three genes (A, B, C) are involved, the presence of dominant alleles (A, B, C) results in darker skin, while recessive alleles lead to lighter skin.

**Hint**: Visualize how combining different alleles can create a range of outcomes rather than just two.

5. **Examples of Quantitative Traits**:
- Traits like human height and skin color exemplify quantitative inheritance because they do not fall into distinct categories but rather show a gradient of phenotypes. This is different from Mendelian traits, which are typically binary.

**Hint**: Think of other traits in nature that show a gradual change rather than a clear division.

6. **Conclusion**:
- Therefore, the statement that when the inheritance of a character is determined by many genes with a cumulative effect, it is called quantitative inheritance, is correct. This type of inheritance is characterized by continuous variation and is often seen in traits influenced by multiple genes.

**Hint**: Summarize the key points about quantitative inheritance and how it differs from Mendelian inheritance.