Which one of the following are intracellular obligate parasites
(a) Bacteria
(b) Slime molds
(c) Viruses
(d) Blue-green algae

Options

A. Bacteria
B. Slime moulds
C. Viruses
D. Blue-green algae.

Answer

To determine which of the following options are intracellular obligate parasites, we need to analyze each option based on the definition of intracellular obligate parasites. Here’s the step-by-step solution:

### Step 1: Understand the Definition
An intracellular obligate parasite is an organism that must live and reproduce inside the cells of a host organism. It cannot survive outside of a host.

### Step 2: Analyze Each Option
- **(a) Bacteria**: Some bacteria can be intracellular parasites (like Chlamydia), but many can also survive outside of host cells (facultative). Therefore, they are not strictly obligate intracellular parasites.

- **(b) Slime molds**: Slime molds are not parasites; they are a type of protist that can feed on decaying organic matter. Thus, they do not fit the definition of an intracellular obligate parasite.

- **(c) Viruses**: Viruses are classic examples of intracellular obligate parasites. They cannot replicate or survive without infecting a host cell. They rely entirely on the host's cellular machinery to reproduce.

- **(d) Blue-green algae**: Blue-green algae (cyanobacteria) are photosynthetic organisms and are not parasites. They can live independently and do not require a host to survive.

### Step 3: Conclusion
Based on the analysis, the only option that fits the definition of an intracellular obligate parasite is **(c) Viruses**.

### Final Answer
The correct answer is **(c) Viruses**.

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