Cyanobacteria are

Options

A. gram positive photosynthetic prokaryotes
B. gram negative photosynthetic prokaryotes
C. gram negative photosynthetic protists
D. gram positive photosynthetic eukaryotes

Answer

**Step-by-Step Solution:**

1. **Identify the Organism**: The question asks about cyanobacteria. Recognize that cyanobacteria are also known as blue-green algae.

2. **Classification**: Understand that organisms are classified into two major categories: prokaryotes and eukaryotes. Cyanobacteria fall under the category of prokaryotes because they lack a true nucleus and membrane-bound organelles.

3. **Photosynthetic Nature**: Cyanobacteria are photosynthetic organisms. This means they can produce their own food through photosynthesis, similar to algae. They contain pigments such as chlorophyll and phycobilins, which allow them to perform photosynthesis.

4. **Gram Staining**: The question mentions gram-positive and gram-negative classifications. Cyanobacteria are classified as gram-negative bacteria. This classification is based on the structure of their cell wall, which has a thin layer of peptidoglycan.

5. **Analyze the Options**: The options provided in the question include:
- Gram positive photosynthetic prokaryotes
- Gram negative photosynthetic prokaryotes
- Gram negative photosynthetic protist
- Gram positive photosynthetic eukaryotes

Since cyanobacteria are prokaryotes and are classified as gram-negative, the correct option is "gram negative photosynthetic prokaryotes."

6. **Conclusion**: The correct answer to the question is that cyanobacteria are gram-negative photosynthetic prokaryotes.

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