all of the following statements concerning the actinomycetous filamentous soil bacterium Frankia are correct except that Frankia

Options

A. Can induce root nodules on many plant species
B. Can fix nitrogen in the free-living state
C. Like Rhizobium, it usually infects its host plant through root hair deformation and stimulates cell proliferation in the host's cortex
D. Forms specialized vesicles in which the nitrogenase is protected from oxygen by a chemical barrier involving triterpene hopanolds

Answer

To solve the question regarding the actinomycetous filamentous soil bacterium Frankia, we need to analyze the provided statements and identify which one is incorrect. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Characteristics of Frankia
Frankia is a genus of filamentous, nitrogen-fixing bacteria that form symbiotic relationships with various plants. They are known for inducing root nodule formation, similar to the process seen in legumes with rhizobium.

**Hint:** Recall that Frankia is involved in nitrogen fixation and forms symbiotic relationships with plants.

### Step 2: Review the Statements
We need to evaluate the following statements about Frankia:
1. Can induce root nodule on many plant species.
2. Can fix nitrogen in a free-living state.
3. Infects its host plant through root hair deformation and stimulates cell proliferation in the host cortex.
4. Forms vesicles in which nitrogen is protected from oxygen by a chemical barrier involving triterpene harpeners.

**Hint:** List out the characteristics of Frankia and compare them with each statement.

### Step 3: Analyze Each Statement
- **Statement 1:** Correct. Frankia can induce root nodules on various plant species.
- **Statement 2:** Incorrect. Frankia does not fix nitrogen in a free-living state; it primarily does so in a symbiotic association with plants.
- **Statement 3:** Correct. Frankia infects host plants through root hair deformation and stimulates cell proliferation.
- **Statement 4:** Correct. Frankia forms vesicles that protect nitrogen from oxygen, involving a chemical barrier.

**Hint:** Focus on the nitrogen-fixing capabilities of Frankia and its symbiotic nature.

### Step 4: Identify the Incorrect Statement
From the analysis, we see that Statement 2 is the only one that is incorrect. Frankia does not fix nitrogen in a free-living state; it requires a symbiotic relationship with plants to do so.

**Hint:** Look for the statement that contradicts the known behavior of Frankia regarding nitrogen fixation.

### Final Answer
The statement concerning Frankia that is incorrect is: **"Can fix nitrogen in free living state."**