Which is a prokaryote ?

Options

A. Rhizopus
B. Spirogyra
C. Nostoc
D. Saccharomyces.

Answer

To determine which of the given options is a prokaryote, we can follow these steps:

### Step 1: Understand the Definition of Prokaryotes
Prokaryotes are unicellular organisms that belong to the Kingdom Monera. They are characterized by the absence of a well-defined nucleus and membrane-bound organelles.

**Hint:** Remember that prokaryotes are unicellular and lack a nucleus.

### Step 2: Analyze the Options
We have four options to consider: Rhizopus, Spirogyra, Nostoc, and Saccharomyces. We will evaluate each one based on their classification.

**Hint:** Look for the kingdom each organism belongs to.

### Step 3: Evaluate Each Option
1. **Rhizopus**: This organism is a type of fungus and belongs to the Kingdom Fungi, which means it is a eukaryote. Therefore, Rhizopus is not a prokaryote.

**Hint:** Fungi are eukaryotic organisms.

2. **Spirogyra**: This is a green algae that belongs to the Kingdom Plantae, which also classifies it as a eukaryote. Thus, Spirogyra is not a prokaryote.

**Hint:** Algae are typically eukaryotic.

3. **Nostoc**: Nostoc is a type of blue-green algae, also known as cyanobacteria. Cyanobacteria are classified under the Kingdom Monera, making Nostoc a prokaryote.

**Hint:** Cyanobacteria are prokaryotic organisms.

4. **Saccharomyces**: This is a genus of yeast that belongs to the Kingdom Fungi, classifying it as a eukaryote. Hence, Saccharomyces is not a prokaryote.

**Hint:** Yeasts are also eukaryotic.

### Step 4: Conclusion
After evaluating all the options, we find that the only prokaryote among the choices is **Nostoc**.

**Final Answer:** The prokaryote is **Nostoc**.