Which one of the following is not true of prokaryotes ?
(a) They are living cells
(b) They lack a nucleus
(c) They all are parasitic
(d) They are both archaea and bacteria

Options

A. They are living cells
B. They lack a nucleus
C. They all are parasitic
D. They are both archaea and bacteria

Explanation

To determine which statement is not true of prokaryotes, let's analyze each option step by step.

1. **Option (a): They are living cells.**
- Prokaryotes are indeed living organisms. They are one of the earliest forms of life on Earth. Therefore, this statement is true.

2. **Option (b): They lack a nucleus.**
- Prokaryotic cells do not have a defined nucleus. Instead, their genetic material is located in a region called the nucleoid, which is not membrane-bound. Thus, this statement is also true.

3. **Option (c): They all are parasitic.**
- This statement is not true. While some prokaryotes can be parasitic (like certain bacteria), not all prokaryotes are parasitic. Many are free-living and play essential roles in ecosystems, such as decomposers or nitrogen-fixers. Therefore, this statement is false.

4. **Option (d): They are both archaea and bacteria.**
- Prokaryotes are classified into two main domains: Archaea and Bacteria. This statement is true.

Based on the analysis, the statement that is not true of prokaryotes is:

**Answer: (c) They all are parasitic.**

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