Question

The organisms Cyanobacteria were formerly known as

• A. Blue green algae
• B. Beijerinckia
• C. Green green algae
• D. Streptococci

Hint:

Cyan = Blue-green color.
BGA = Cyanobacteria.
Even though they are called "Algae," they are actually Bacteria.
They were the first organisms to release oxygen into the Earth's atmosphere!

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for the traditional name of the phylum of bacteria that obtain their energy through photosynthesis.
Detailed Explanation:

• Introduction to Cyanobacteria:
Cyanobacteria are a group of photosynthetic bacteria. They are unique among bacteria because they produce oxygen as a byproduct of photosynthesis (like plants).

• Former Classification:
Because they possess chlorophyll and look like algae under a microscope, they were traditionally classified as plants and called "Blue Green Algae" (BGA).
However, they are prokaryotic (lacking a nucleus), whereas true algae are eukaryotic. Therefore, modern taxonomy renamed them Cyanobacteria to reflect their true bacterial nature.

• Role in Agriculture:
Many cyanobacteria (like Anabaena, Nostoc) can fix atmospheric nitrogen in specialized cells called heterocysts. They are widely used as biofertilizers in rice (paddy) fields.

• Analyzing other options:
Beijerinckia: A genus of free-living aerobic nitrogen-fixing bacteria.
Streptococci: A genus of coccus-shaped bacteria, often associated with diseases.
Green algae: These are true eukaryotic algae (Chlorophyta).

Step 2: Final Answer:
Cyanobacteria were formerly known as Blue Green Algae.