Question

Which of the following acts as a biofertilizer?

• A. Blue-green algae
• B. Green algae
• C. Yellow algae
• D. Red algae

Hint:

Important blue-green algae used as biofertilizers:
Anabaena
Nostoc They fix atmospheric nitrogen and enrich soil fertility. Remember: \[ \boxed{\text{Blue-green algae (Cyanobacteria) = Biofertilizers}} \] This is a very common NCERT-based CUET and NEET question.

Answer 1

The Correct Option is A

Step 1: Recall the concept of biofertilizers. Biofertilizers are microorganisms that improve soil fertility by increasing the availability of nutrients, especially nitrogen.

Step 2: Identify the algae used as biofertilizers. Blue-green algae (cyanobacteria) such as: \[ \textit{Anabaena} \] \[ \textit{Nostoc} \] possess nitrogen-fixing ability and are widely used in paddy fields.

Step 3: Evaluate the given options.
• Blue-green algae \(\rightarrow\) Important biofertilizers due to nitrogen fixation \(\checkmark\)
• Green algae \(\rightarrow\) Not commonly used as biofertilizers \(\times\)
• Yellow algae \(\rightarrow\) Not used as biofertilizers \(\times\)
• Red algae \(\rightarrow\) Not used as biofertilizers \(\times\) Therefore, \[ \boxed{\text{Blue-green algae}} \] act as biofertilizers. Hence, the correct answer is: \[ \boxed{\text{(A)}} \]