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 about prokaryotic and eukaryotic cells, let's analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement Analysis**:
- **Statement 1**: "All prokaryotes lack nuclear envelope. But nuclear envelope is present in mitochondria of eukaryotes."
- **Analysis**: This statement is incorrect. While it is true that prokaryotes lack a nuclear envelope, the nuclear envelope is not present in mitochondria; rather, it surrounds the nucleus of eukaryotic cells.

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 many eukaryotes (like plants and fungi) do have a cell wall, animal cells (which are also eukaryotic) do not have a cell wall. Mycoplasma, being a prokaryote, indeed lacks a cell wall, but the statement about all eukaryotes having a cell wall is incorrect.

3. **Statement 3**: "All eukaryotes are identical but all prokaryotes are not identical."
- **Analysis**: This statement is incorrect. Eukaryotic cells can vary widely in structure and function (e.g., plant cells vs. animal cells), so they are not identical. Prokaryotic cells also exhibit diversity among different species.

4. **Statement 4**: "Most of the eukaryotic chromosomes are associated with histone proteins but the genome of chloroplasts lacks histone."
- **Analysis**: This statement is correct. Eukaryotic chromosomes are typically associated with histone proteins, which help in packaging DNA into a compact structure. However, the DNA found in chloroplasts (which are semi-autonomous organelles) does not have histone proteins associated with it.

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

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