In Nostoc// bacteria//procaryotes the ribosomes are

Options

A. 50 S
B. 80 S
C. 70 S
D. 30 S.

Answer

**Step-by-Step Solution:**

1. **Understanding Ribosomes:**
- Ribosomes are essential cellular structures found in all living organisms, including bacteria and prokaryotes. They serve as the site for protein synthesis.

2. **Identifying Ribosome Types:**
- Ribosomes are categorized based on their sedimentation rates, measured in Svedberg units (S). The main types are:
- 30S and 50S subunits combine to form a 70S ribosome in prokaryotes.
- 40S and 60S subunits combine to form an 80S ribosome in eukaryotes.

3. **Ribosomes in Prokaryotes:**
- All prokaryotes, including Nostoc and other bacteria, contain 70S ribosomes. This is a defining characteristic of prokaryotic cells.

4. **Evaluating the Options:**
- The options given are:
- 50S
- 80S
- 70S
- 30S
- Since prokaryotes have 70S ribosomes, we can eliminate the other options:
- 50S is a subunit of the 70S ribosome.
- 80S ribosomes are found in eukaryotes.
- 30S is also a subunit of the 70S ribosome.

5. **Conclusion:**
- Therefore, the correct answer is that in Nostoc, bacteria, and prokaryotes, the ribosomes are **70S**.

**Final Answer:**
- In Nostoc, bacteria, and prokaryotes, the ribosomes are **70S**.

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