In the given options , there is q property of a group and a representative example following that property . Which of these is incorrect ?

Options

A. All prokaryotes classified under kingdom Monera have cell wall ( Mycoplasma )
B. All viroids have single stranded RNA as genetic material ( Potato Tube spindle Viroid )
C. All Prions don't have nucleic acid as their genetic material ( Bovine Spongiform Encephalopathy prion )
D. Unicellular plants have been placed in Kingdom Protista by Whittaker (Chlorella)

Answer

To solve the question, we need to evaluate each option provided to identify which statement is incorrect regarding the properties of groups and their representative examples.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks us to identify the incorrect statement among the given options related to biological classifications.

2. **Evaluating Option 1**:
- Statement: "All prokaryotes classified under the kingdom of Monera have a cell wall. Example: Mycoplasma."
- Analysis: Mycoplasma is known to be a prokaryote that lacks a cell wall. Therefore, this statement is incorrect because it contradicts the fact that not all prokaryotes have a cell wall.

3. **Evaluating Option 2**:
- Statement: "All viroids have single-stranded RNA as genetic material. Example: Potato spindle tuber viroid."
- Analysis: This statement is correct. Viroids are indeed characterized by having single-stranded RNA, and the potato spindle tuber viroid is a valid example.

4. **Evaluating Option 3**:
- Statement: "All prions don't have nucleic acid as their genetic material. Example: Bovine spongiform encephalopathy prion."
- Analysis: This statement is also correct. Prions are infectious agents that do not contain nucleic acids, and bovine spongiform encephalopathy is a well-known prion disease.

5. **Evaluating Option 4**:
- Statement: "Unicellular plants have been placed in the kingdom of Protista. Example: Chlorella."
- Analysis: This statement is correct as well. Chlorella is a unicellular green alga classified under the kingdom Protista.

6. **Conclusion**: After evaluating all options, the incorrect statement is from Option 1: "All prokaryotes classified under the kingdom of Monera have a cell wall. Example: Mycoplasma." This is incorrect because Mycoplasma does not have a cell wall.

### Final Answer:
The incorrect option is **Option 1**: "All prokaryotes classified under the kingdom of Monera have a cell wall. Example: Mycoplasma."