Which of the following statement are true for genetic drift ?
I. It upsets the Hardy-Weinberg equilbrium
II. It operates only in small population
III. It is responsible for preserving certain genes
IV. It is responsible for eliminating certain genes

Options

A. I,II,III
B. II,III,IV
C. I,II,IV
D. I,II,III,IV

Answer

To determine which statements about genetic drift are true, let's analyze each statement step by step:

### Step 1: Analyze Statement I
**Statement I: It upsets the Hardy-Weinberg equilibrium.**

- **Explanation**: The Hardy-Weinberg equilibrium states that allele frequencies in a population remain constant from generation to generation in the absence of evolutionary influences. Genetic drift, which is a random change in allele frequencies, can disrupt this equilibrium. Therefore, this statement is **true**.

### Step 2: Analyze Statement II
**Statement II: It operates only in small populations.**

- **Explanation**: Genetic drift has a more pronounced effect in small populations because random events can significantly alter allele frequencies. In larger populations, these random changes tend to average out. Thus, this statement is also **true**.

### Step 3: Analyze Statement III
**Statement III: It is responsible for preserving certain genes.**

- **Explanation**: Genetic drift does not preserve genes; rather, it can lead to the loss of alleles from a population. It is more about random changes that may eliminate certain alleles rather than preserving them. Therefore, this statement is **false**.

### Step 4: Analyze Statement IV
**Statement IV: It is responsible for eliminating certain genes.**

- **Explanation**: Genetic drift can lead to the elimination of alleles from a population, especially through mechanisms like the bottleneck effect and founder effect. Hence, this statement is **true**.

### Summary of Findings
Based on the analysis:
- Statement I: True
- Statement II: True
- Statement III: False
- Statement IV: True

Thus, the true statements for genetic drift are I, II, and IV.

### Final Answer
The true statements about genetic drift are: **I, II, and IV.**

---