Which statement is not true :-

Options

A. Genetics deals with the inheritance , as well as the variation of characters from parents to offspring
B. Characters are controlled by discrete units called factor
C. Co-dominance present in 'AB' blood group
D. Linkage `prop` distance between two gene present in one chromosome

Answer

To determine which statement is not true, we will analyze each option provided in the question step by step.

### Step 1: Analyze the first statement
- **Statement**: Genetics deals with the inheritance as well as variations of the character from the parents to offspring.
- **Analysis**: This statement is true. Genetics is indeed the study of how traits and characteristics are passed from parents to offspring, including variations.

### Step 2: Analyze the second statement
- **Statement**: Characters are controlled by discrete or equal factors.
- **Analysis**: This statement is also true. The term "factors" refers to genes, as introduced by Gregor Mendel. Genes are the discrete units that control traits.

### Step 3: Analyze the third statement
- **Statement**: Co-dominance is present in the AB blood group system.
- **Analysis**: This statement is true as well. In the AB blood group system, both A and B alleles are expressed equally, which is a classic example of co-dominance.

### Step 4: Analyze the fourth statement
- **Statement**: Linkage is directly proportional to the distance between two genes present on the chromosome.
- **Analysis**: This statement is not true. In genetics, linkage refers to the tendency of genes that are located close to each other on a chromosome to be inherited together. As the distance between genes increases, the likelihood of them being inherited together (linkage) decreases. Therefore, linkage is inversely proportional to the distance between genes.

### Conclusion
The statement that is not true is the last one: "Linkage is directly proportional to the distance between two genes present on the chromosome."

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