Test: Biogeochemical Cycles

5 Questions MCQ Test Science Class 9 | Test: Biogeochemical Cycles

This mock test of Test: Biogeochemical Cycles for Class 9 helps you for every Class 9 entrance exam. This contains 5 Multiple Choice Questions for Class 9 Test: Biogeochemical Cycles (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Biogeochemical Cycles quiz give you a good mix of easy questions and tough questions. Class 9 students definitely take this Test: Biogeochemical Cycles exercise for a better result in the exam. You can find other Test: Biogeochemical Cycles extra questions, long questions & short questions for Class 9 on EduRev as well by searching above.

Carbon is incorporated into life-forms through:

By the process of photosynthesis, carbon dioxide is fixed and converted into carbohydrates.


The transfer of matter and energy between different components of biosphere is called:


The organisms responsible for returning nutrients to the ecosystem include:

Every part of an ecosystem is vital to its survival – from the green plants to furry animals and microscopic bacteria. The group of organisms called decomposers forms the final link in the food chain. They break down dead animals and plants and return vital nutrients to the soil.

Through which process is oxygen returned to the atmosphere?


Nitrogen-fixation by bacteria does not occur in the presence of:

Certain bacteria such as Azotobacter (occur freely in the soil) and Rhizobium (occur in root nodules of leguminous plants as pea, gram, bean, etc), convert the atmospheric nitrogen into water soluble nitrates. The process of biofixation of nitrogen is called as nitrogen fixation.
Enzymes required for biofixation of nitrogen are nitrogenases. There nitrogenases are very suseptible to destruction by oxygen. Many bacteria cease the production of enzymes in the presence of oxygen. Many nitrogen fixing bacteria grow in anaerobic conditions or respire to bring down oxygen levels or binding oxygen with the proteins like leg haemoglobin.

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