Which is not true of prokaryotes?

Options

A. They are living cells
B. They lack a nucleus
C. They are either archaebacteria or eubacteria
D. All are parasitic

Explanation

To determine which statement is not true of prokaryotes, we can analyze the characteristics of prokaryotic cells. Here’s a step-by-step breakdown:

### Step 1: Understand Prokaryotes
Prokaryotes are defined as microscopic, single-celled organisms that lack a distinct nucleus and membrane-bound organelles. They are classified into two main categories: archaebacteria and eubacteria.

**Hint:** Remember that prokaryotes are simple organisms without a nucleus.

### Step 2: Analyze the Options
We will evaluate each option provided in the question to identify which statement is incorrect.

1. **They are living cells.**
- This statement is true. Prokaryotes are indeed living cells.

2. **They lack a nucleus.**
- This statement is also true. Prokaryotes do not have a defined nucleus.

3. **They are either archaebacteria or eubacteria.**
- This statement is true as well. Prokaryotes are classified into these two groups.

4. **All are parasitic.**
- This statement is not true. While some prokaryotes can be parasitic, many are non-parasitic and can be beneficial or neutral.

### Step 3: Conclusion
Based on the analysis, the statement that is not true of prokaryotes is: **"All are parasitic."**

Therefore, the correct answer is option D: **All are parasitic.**