Chapter 23, Problem 1RE

RECALL What kinds of organisms can fix nitrogen? Which ones cannot?

Interpretation Introduction

Interpretation:

The types of organisms that may or may not fix nitrogen is to be determined.

Concept Introduction:

The microorganisms that can convert the atmospheric nitrogen into fixed nitrogen, such as ammonia that is used by the plants are known as nitrogen-fixing organisms. These organisms play an important role in the nitrogen cycle.

Answer to Problem 1RE

Solution: Organisms that can fix nitrogen – symbiotic and non-symbiotic bacteria.

Organisms that cannot fix nitrogen – plants and animals.

Explanation of Solution

Nitrogen fixating bacteria are the prokaryotic microorganisms that can convert nitrogen from the atmosphere into fixed nitrogen compounds that are usable by plants. There are generally two kinds of nitrogen-fixing bacteria. The first kind is symbiotic bacteria that includes Rhizobium, which is associated with the leguminous plants. These bacteria form nodules on the roots of the leguminous plants, such as beans and alfalfa.

The second category includes the non-symbiotic bacteria that includes free-living microbes and cyanobacteria.

Plants and animals cannot fix nitrogen or behave as nitrogen-fixing organisms. But they require nitrogen for their growth and development.

Conclusion

The kind of organisms that may or may not fix nitrogen is determined.