Which Of the following statement are correct
I.Mycoplasmas are the smallest cells
II.Nerve cells are the longest cells of our body
III.Ribosomes are non membrane bound organelles found only in eukaryotic cells
IV.The cytoplasm is the main arena of cellular activities only in plant cells.

Options

A. I,II,III
B. I,II
C. II,III
D. I,II,III,IV

Answer

To determine which of the statements are correct, we will analyze each statement one by one.

### Step 1: Evaluate Statement I
**Statement I:** Mycoplasmas are the smallest cells.
- Mycoplasmas are indeed the smallest known cells, with a diameter of approximately 0.2 to 0.4 micrometers. They lack a cell wall and are classified as bacteria.
- **Conclusion:** This statement is **correct**.

### Step 2: Evaluate Statement II
**Statement II:** Nerve cells are the longest cells of our body.
- Nerve cells, or neurons, can be very long, with some extending up to 3 feet (approximately 1 meter) in length. This makes them among the longest cells in the human body.
- **Conclusion:** This statement is **correct**.

### Step 3: Evaluate Statement III
**Statement III:** Ribosomes are non-membrane bound organelles found only in eukaryotic cells.
- Ribosomes are indeed non-membrane bound organelles, but they are found in both prokaryotic and eukaryotic cells. Prokaryotic ribosomes are 70S, while eukaryotic ribosomes are 80S.
- **Conclusion:** This statement is **incorrect**.

### Step 4: Evaluate Statement IV
**Statement IV:** The cytoplasm is the main arena of cellular activities only in plant cells.
- The cytoplasm is the gel-like substance within all cells (both prokaryotic and eukaryotic) where various cellular activities occur. It is not limited to plant cells.
- **Conclusion:** This statement is **incorrect**.

### Final Conclusion
- The correct statements are:
- I. Mycoplasmas are the smallest cells. (Correct)
- II. Nerve cells are the longest cells of our body. (Correct)
- III. Ribosomes are non-membrane bound organelles found only in eukaryotic cells. (Incorrect)
- IV. The cytoplasm is the main arena of cellular activities only in plant cells. (Incorrect)

Thus, the correct answers are statements I and II.

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