Q11 of 75 Page 438

The nitrogen molecules present in air can be converted into nitrates and nitrites by:

Nitrifying bacteria in the soil convert ammonia into nitrite (NO2-) and then into nitrate (NO3-). This process is called nitrification. Compounds such as nitrate, nitrite, ammonia and ammonium can be taken up from soils by plants and then used in the formation of proteins.

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In nature, carbon is found in elemental forms as:

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The endoskeletons and exoskeletons of various animals are also formed from :

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One of the following processes is not a step involved in the water cycle operating in nature:

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The term “water pollution” can be defined in several ways. Which of the following statements does not give the correct definition?