MHT CET Medical202626 April 2026Morning ShiftBiologyMineral NutritionActual
Given below are two statements regarding nitrogen fixation in plants. Statement I - Nitrogen fixing bacteria use high energy to fix each molecule of nitrogen to form ammonia, which is an exothermic reaction. Statement II - Chemoautotrophic bacteria obtain energy during nitrification of ammonia into nitrate, which is an endothermic reaction. In the light of the above statements, select the correct option given below:
Options
- ABoth statement I and statement II are correct.
- BBoth statement I and statement II are incorrect.
- CStatement I is correct but statement II is incorrect.
- DStatement I is incorrect but statement II is correct.
Correct answer
B. Both statement I and statement II are incorrect.
Step-by-step solution
Statement I is incorrect because biological nitrogen fixation requires a very high input of energy ( 8 ATP for each NH ₃ produced). Since it requires energy, it is an endothermic process, not an exothermic one. Statement II is incorrect because nitrification involves the oxidation of ammonia into nitrite and then into nitrate. Oxidation reactions release energy, making nitrification an exothermic process, not an endothermic one. Chemoautotrophic bacteria utilize this released energy to synthesize their food. Theref