A few statements are made about the characteristics of prokaryotic and eukaryotic cells.
Mark the correct statement .

Options

A. All prokaryotes lack nuclear envelope but nuclear envelope is present in mitochondria of eukaryotes.
B. All eukaryotes have a cell wall surrounding the cell membrane but cell wall is absent in mycoplasma.
C. All eukaryotic cells are identical but all prokaryotic cells are not identical.
D. Most of the eukaryotic chromosomes are associated with histone protein but the genome of chloroplast lack histones.

Answer

To determine the correct statement regarding prokaryotic and eukaryotic cells, we will analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Statement Analysis**:
- **Statement 1**: "All prokaryotes lack nuclear envelope but nuclear envelope is present in mitochondria of eukaryotes."
- **Analysis**: It is true that prokaryotes lack a nuclear envelope. However, the claim that the nuclear envelope is present in mitochondria is incorrect. The nuclear envelope surrounds the nucleus, not the mitochondria. Therefore, this statement is **partially correct** but ultimately **incorrect** due to the second part.

2. **Statement 2**: "All eukaryotes have a cell wall surrounding the cell membrane but cell wall is absent in mycoplasma."
- **Analysis**: This statement is misleading. While plant cells (a type of eukaryotic cell) have a cell wall, animal cells do not. Therefore, not all eukaryotes have a cell wall. The second part about mycoplasma is correct, as mycoplasma are a type of bacteria that lack a cell wall. Thus, this statement is **incorrect**.

3. **Statement 3**: "All eukaryotic cells are identical but all prokaryotic cells are not identical."
- **Analysis**: This statement is incorrect. Eukaryotic cells can vary significantly (e.g., plant cells vs. animal cells), and prokaryotic cells can also differ (e.g., bacteria vs. mycoplasma). Therefore, this statement is **incorrect**.

4. **Statement 4**: "Most of the eukaryotic chromosomes are associated with histone protein but genome of chloroplast lacks histone."
- **Analysis**: This statement is correct. In eukaryotic cells, most chromosomes are indeed associated with histone proteins, which help package DNA into a compact form. However, the DNA found in chloroplasts (and mitochondria) is circular and does not have histones, aligning with the statement. Therefore, this statement is **correct**.

### Conclusion:
The correct statement is **Statement 4**: "Most of the eukaryotic chromosomes are associated with histone protein but genome of chloroplast lacks histone."

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