Which of the following statement is / are not true
A. Cork cambium is otherwise called phellogen
B. Cork is otherwises called phellem
C. Secondary cortex is otherwise called peirderm
D. Cork cambium, cork and secondary cortex are collectively called phelloderm

Options

A. b and d only
B. b anc c only
C. c and b only
D. a and b only

Answer

To determine which statements are not true regarding cork cambium, cork, and secondary cortex, let's analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement A: Cork cambium is otherwise called phellogen.**
- **Analysis**: This statement is true. Cork cambium is indeed referred to as phellogen. It is the layer of meristematic tissue responsible for producing cork.

2. **Statement B: Cork is otherwise called phellem.**
- **Analysis**: This statement is also true. Cork is known as phellem, which is the outer protective layer produced by the cork cambium.

3. **Statement C: Secondary cortex is otherwise called periderm.**
- **Analysis**: This statement is false. The term "periderm" refers to the protective tissue that includes the cork (phellem), cork cambium (phellogen), and the secondary phloem. The secondary cortex is not synonymous with periderm.

4. **Statement D: Cork cambium, cork, and secondary cortex are collectively called phelloderm.**
- **Analysis**: This statement is also false. The term "phelloderm" refers specifically to the layer of cells produced by the cork cambium that lies beneath the cork. Therefore, cork cambium, cork, and secondary cortex are not collectively referred to as phelloderm.

### Conclusion:
The statements that are not true are **C and D**.

### Final Answer:
- **C and D are not true.**

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