Question

Which of the following are Cyanobacteria?
(A) Nucleopolyhedrovirus
(B) Anabaena
(C) Nostoc
(D) Oscillatoria
Choose the correct answer from the options given below:

• A. (A), (B), and (D) only
• B. (A), (B), and (C) only
• C. (B), (C), and (D)
• D. (B), (C), and (D) only

Answer 1

The Correct Option is D

Cyanobacteria, also known as blue-green algae, are a group of photosynthetic microorganisms that are capable of oxygenic photosynthesis. They are significant in agriculture due to their ability to fix atmospheric nitrogen, thus enhancing soil fertility. 

Let's examine each option to identify which organisms are cyanobacteria:

• (A) Nucleopolyhedrovirus: This is not a cyanobacterium. Nucleopolyhedroviruses are a group of viruses that infect insects and are used in biological pest control.
• (B) Anabaena: This is a type of cyanobacterium known for its ability to fix nitrogen, thriving in aquatic environments or on soils.
• (C) Nostoc: Another cyanobacterium, Nostoc forms symbiotic relationships with plants, contributing to nitrogen fixation.
• (D) Oscillatoria: This is a filamentous cyanobacterium found in freshwater and marine environments, known for its oscillation movements.

Hence, the correct options that are cyanobacteria are:

(B)	Anabaena
(C)	Nostoc
(D)	Oscillatoria

The correct answer is: (B), (C), and (D) only.

Answer 2

The correct answer is (4) (B), (C) and (D) only.

Cyanobacteria (also known as blue-green algae) are a group of photosynthetic bacteria that are found in various aquatic and terrestrial habitats. They are capable of producing their own food through photosynthesis and are known for their role in nitrogen fixation.

(B) Anabaena: Anabaena is a cyanobacterium known for its ability to fix nitrogen. It forms filaments and is often found in freshwater environments.

(C) Nostoc: Nostoc is another cyanobacterium that forms gelatinous colonies and is involved in nitrogen fixation.

(D) Oscillatoria: Oscillatoria is a type of cyanobacterium that forms long, filamentous chains. It is known for its oscillatory movement in water.

(A) Nucleopolyhedroviral is not a cyanobacterium; it is a virus that infects insects, particularly caterpillars.

Thus, the correct answer is (4) (B), (C) and (D) only, as all three of these are cyanobacteria.