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Ch. 27 - Environmental Microbiology
Tortora - Microbiology: An Introduction 14th Edition
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook
All textbooksTortora 14th EditionCh. 27 - Environmental MicrobiologyProblem 10
Chapter 27, Problem 10

These nitrogen-fixing prokaryotes provide nitrogen fertilizer in rice paddies; they live symbiotically in the cells of the freshwater plant Azolla.

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Identify the key characteristics described: nitrogen-fixing prokaryotes that provide nitrogen fertilizer in rice paddies and live symbiotically inside the freshwater plant Azolla.
Recall that nitrogen-fixing prokaryotes convert atmospheric nitrogen (N\_2) into ammonia (NH\_3), which plants can use for growth, a process called biological nitrogen fixation.
Consider the types of nitrogen-fixing bacteria associated with aquatic plants, especially those forming symbiotic relationships inside plant cells.
Recognize that the genus Anabaena, a filamentous cyanobacterium, is known for living symbiotically within Azolla and fixing nitrogen in rice paddies.
Conclude that the nitrogen-fixing prokaryotes described are cyanobacteria of the genus Anabaena, which provide nitrogen fertilizer through their symbiotic relationship with Azolla.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Nitrogen Fixation

Nitrogen fixation is the biological process where certain prokaryotes convert atmospheric nitrogen (N2) into ammonia (NH3), a form usable by plants. This process enriches soil nitrogen content, supporting plant growth, especially in nitrogen-poor environments like rice paddies.
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Symbiotic Relationships in Microbiology

Symbiosis refers to a close, long-term interaction between two different species. In microbiology, some nitrogen-fixing bacteria live inside plant cells, providing essential nutrients while receiving shelter and carbohydrates, exemplifying mutualism.
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Symbiotic Relationships

Azolla and Its Nitrogen-Fixing Prokaryotes

Azolla is a freshwater fern that hosts nitrogen-fixing cyanobacteria, specifically Anabaena, within its leaf cavities. This symbiosis supplies nitrogen fertilizer naturally to rice paddies, reducing the need for chemical fertilizers.
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Related Practice
Textbook Question

Coliforms are used as indicator organisms of sewage pollution because

a. They are pathogens.

b. They ferment lactose.

c. They are abundant in human intestines.

d. They grow within 48 hours.

e. All of the above.

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Textbook Question

Use the following choices to answer the question:

a. Aerobic respiration

b. Anaerobic respiration

c. Anoxygenic photosynthesis

d. Oxygenic photosynthesis

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Textbook Question

Bioremediation refers to the use of living organisms to remove pollutants. Describe three examples of bioremediation.

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Textbook Question

All of the following are effects of water pollution except

a. The spread of infectious diseases.

b. Increased eutrophication.

c. Increased BOD.

d. Increased growth of algae.

e. None of the above; all of these are effects of water pollution.

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