Question:
Free living microbes in soil but as symbionts fix atmospheric nitrogen are
Free living microbes in soil but as symbionts fix atmospheric nitrogen are
Show Hint
Rhizobium forms nodules in legumes, whereas Frankia forms nodules in several non-leguminous plants. Both are famous symbiotic nitrogen fixers.
Updated On: Jun 12, 2026
- Rhizobium and Azotobacter
- Oscillatoria and Frankia
- Trichoderma and Azospirillum
- Rhizobium and Frankia
Show Solution
Verified By Collegedunia
The Correct Option is D
Solution and Explanation
Concept:
Biological nitrogen fixation converts atmospheric nitrogen into ammonia with the help of certain microorganisms.
Nitrogen-fixing organisms may be:
• Free-living
• Symbiotic Some microorganisms are capable of existing freely in soil but perform nitrogen fixation mainly in association with plants.
Step 1: Understand Rhizobium. Rhizobium is a bacterium that forms root nodules in leguminous plants. Within these nodules it fixes atmospheric nitrogen. Although it can survive in soil, efficient nitrogen fixation occurs in symbiosis.
Step 2: Understand Frankia. Frankia is an actinomycete associated with roots of non-leguminous plants such as Alnus and Casuarina. It also fixes atmospheric nitrogen in a symbiotic relationship.
Step 3: Examine other organisms. Azotobacter is primarily a free-living nitrogen fixer. Oscillatoria generally does not represent the classic symbiotic nitrogen-fixing association asked here. Trichoderma acts mainly as a biocontrol agent. Azospirillum is a free-living or associative nitrogen fixer.
Step 4: Final conclusion. The microorganisms that live freely in soil but fix nitrogen as symbionts are: \[ \boxed{\text{Rhizobium and Frankia}} \] Hence option (D) is correct.
• Free-living
• Symbiotic Some microorganisms are capable of existing freely in soil but perform nitrogen fixation mainly in association with plants.
Step 1: Understand Rhizobium. Rhizobium is a bacterium that forms root nodules in leguminous plants. Within these nodules it fixes atmospheric nitrogen. Although it can survive in soil, efficient nitrogen fixation occurs in symbiosis.
Step 2: Understand Frankia. Frankia is an actinomycete associated with roots of non-leguminous plants such as Alnus and Casuarina. It also fixes atmospheric nitrogen in a symbiotic relationship.
Step 3: Examine other organisms. Azotobacter is primarily a free-living nitrogen fixer. Oscillatoria generally does not represent the classic symbiotic nitrogen-fixing association asked here. Trichoderma acts mainly as a biocontrol agent. Azospirillum is a free-living or associative nitrogen fixer.
Step 4: Final conclusion. The microorganisms that live freely in soil but fix nitrogen as symbionts are: \[ \boxed{\text{Rhizobium and Frankia}} \] Hence option (D) is correct.
Was this answer helpful?
0
0
Top TS EAMCET Botany Questions
- Flask-shaped ascocarp with an apical opening is:
- In which of the following organisms, cell wall is not found in any stage?
- Assertion (A): In Rhodophyceae, food is stored as floridean starch. Reason (R): Floridean starch is similar to amylopectin and glycogen in structure.
Identify the wrong pair:
Match the following:
View More Questions
Top TS EAMCET Genetics Questions
- Genetic nature of Ribonucleic acid was discovered by:
- Identify the correct combinations:
- The table given below is related to the checkerboard of dihybrid F\(_2\) progeny of Mendel’s experiment. Identify the correct combinations:
- In Morgan’s experiments on linkage in Drosophila, the percentage of white-eyed, miniature-winged recombinants in the F\(_2\) generation is:
- ‘A’ diploid chromosome number is 4. ‘B’ haploid chromosome number is twice to that of A. ‘C’ diploid chromosome number is thrice to that of A. A, B and C respectively are
View More Questions
Top TS EAMCET Questions
- A bag contains $5$ red balls, $3$ black balls and $4$ white balls are drawn at random. The probability that they are not of same colour is
- If $cosec\, \theta - \cot \theta = 2017$, then quadrant in which $\theta $ lies is
- If $a$ is a unit vector, then $| a \times \hat{ i }|^{2}+| a \times \hat{ j }|^{2}+| a \times \hat{ k }|^{2}=$
- $A$ straight line makes an intercept on the $Y$-axis twice as long as that on $X$-axis and is at a unit distance from the origin. Then the line is represented by the equations
- Let $S$ and $S'$ be the foci of an ellipse and B be one end of its minor axis. If $SBS'$ is an isosceles right angled triangle then the eccentricity of the ellipse is
View More Questions