Which is not true for inbreeding ?

Options

A. It causes inbreeding depression after a few generations.
B. It always increases procuctivity.
C. It is used to produce a pure line.
D. It leads to homozygosity.

Answer

### Step-by-Step Solution:

1. **Understanding Inbreeding**: Inbreeding refers to the mating of closely related individuals. It is a common practice in agriculture and animal breeding to produce pure lines with desired traits.

2. **Evaluating the Statements**:
- **Statement 1**: "It causes inbreeding depression after a few generations."
- This statement is true. Inbreeding can lead to inbreeding depression, which is a reduction in biological fitness due to the accumulation of deleterious recessive alleles over generations.

- **Statement 2**: "It always increases productivity."
- This statement is not true. While inbreeding can produce pure lines, it does not guarantee an increase in productivity. In fact, inbreeding can lead to reduced fitness and productivity due to the expression of harmful recessive traits.

- **Statement 3**: "It is used to produce a pure line."
- This statement is true. Inbreeding is often used to create pure lines that have uniform characteristics.

- **Statement 4**: "It leads to homozygosity."
- This statement is true. Inbreeding increases homozygosity, which means that the genetic makeup becomes more uniform.

3. **Conclusion**: The statement that is not true regarding inbreeding is the second one: "It always increases productivity."

### Final Answer:
The statement that is not true for inbreeding is: **"It always increases productivity."**

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