Rhizobium is used as a biofertilizer primarily for: MCQ with Answer and Explanation

Rhizobium is used as a biofertilizer primarily for:
A. Fixing atmospheric nitrogen in legume root nodules
B. Solubilizing phosphates
C. Producing auxins
D. Decomposing organic matter
Answer: Option A
Solution (By JKExamLibrary)
Rhizobium is a symbiotic nitrogen-fixing bacterium that forms root nodules in the roots of leguminous plants (like peas, beans, clover). Inside these nodules, the bacterium converts atmospheric nitrogen (N2) into ammonia (NH3), which the plant can use. In return, the plant provides the bacteria with carbohydrates and a protected environment. It significantly reduces the need for chemical nitrogen fertilizers.

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Practice More Biology Questions

Question #1
The function of the myelin sheath is to:
A. Produce neurotransmitters
B. Decrease the speed of nerve impulse
C. Insulate and increase the speed of nerve impulse conduction
D. Store energy for the neuron

Correct Answer: Option C


Explanation:
Myelin, a lipid-rich sheath formed by Schwann cells (PNS) or oligodendrocytes (CNS), insulates axons, allowing saltatory conduction—impulses jump from one node of Ranvier to the next, greatly speeding up transmission. It also conserves energy. Demyelinating diseases like multiple sclerosis slow conduction.

This question belongs to: Science Biology
Question #2
Antonie van Leeuwenhoek is known for being the first to observe:
A. Living cells (animalcules)
B. Mitochondria
C. Cell division
D. Chromosomes

Correct Answer: Option A


Explanation:
Antonie van Leeuwenhoek, a Dutch linen merchant and amateur scientist, is known as the 'father of microbiology'. Using his own handcrafted, high-quality single-lens microscopes, he was the first person to observe and describe living, single-celled organisms, which he called 'animalcules' (little animals). These included bacteria, protozoa, and sperm cells, in the late 17th century.

This question belongs to: Science Biology
Question #3
The technique of using radioactive probes to detect specific DNA sequences on a membrane is:
A. PCR
B. Flow cytometry
C. Southern blotting
D. ELISA

Correct Answer: Option C


Explanation:
Southern blotting involves separation of DNA fragments by gel electrophoresis, transfer to a membrane, and hybridization with a labeled probe. PCR amplifies DNA, ELISA detects proteins, flow cytometry analyzes cells.

This question belongs to: Science Biology