During secondary growth in dicot root, the layer that becomes outermost protective layer after the disintegration of endodermis, cortex and epiblema is phellem

Options

A. Vascular cambium is completely secondary in origin
B. Vascular cambium arises only from the tissue located just below the phloem bundle
C. Vascular cambium forms continuous but wavyring
D. More than one options is correct

Answer

To answer the question regarding the outermost protective layer formed during secondary growth in dicot roots, we can break down the solution into clear steps:

### Step-by-Step Solution:

1. **Understanding Secondary Growth**:
- Secondary growth in dicot roots involves the increase in thickness of the root due to the activity of the cambium. This process is essential for the plant's growth and support.

**Hint**: Secondary growth is primarily associated with the vascular cambium and the formation of new tissues.

2. **Identifying the Layers**:
- During secondary growth, the root undergoes changes where the endodermis, cortex, and epiblema (outer layer) disintegrate. This disintegration is part of the process that allows for the formation of new protective layers.

**Hint**: Focus on the layers that are present in a dicot root and how they change during growth.

3. **Role of Phellem**:
- The outermost protective layer that forms after the disintegration of the endodermis, cortex, and epiblema is known as phellem. Phellem is part of the periderm, which replaces the epidermis in older stems and roots.

**Hint**: Remember that phellem is also referred to as cork and is crucial for protection.

4. **Confirming the Statement**:
- The statement in question claims that the layer that becomes the outermost protective layer after the disintegration of the endodermis, cortex, and epiblema is phellem. This is true because phellem indeed forms as a result of these changes.

**Hint**: Verify the definitions of phellem and periderm to ensure clarity.

5. **Conclusion**:
- The statement is correct, as phellem is the outermost protective layer formed during secondary growth in dicot roots after the disintegration of the aforementioned layers.

**Hint**: Summarize your findings to reinforce your understanding of the process.

### Final Answer:
The statement is true. During secondary growth in dicot roots, the layer that becomes the outermost protective layer after the disintegration of the endodermis, cortex, and epiblema is called phellem.