Briefly explain carbon cycle in nature.

Explain the oxygen cycle in nature.

State the function of a reservoir in a nutrient cycle. Explain the simplified model of carbon cycle in nature.

Global carbon is fixed in the biosphere through photosynthesis. (a) Explain any two ways by which carbon is returned to the atmosphere through natural processes, (b) List any two human activities that have influenced the carbon cycle in nature.

(a) With the help of well labeled diagram explain water cycle in nature. (b) How is green house effect related to Global warming? Explain.

(a) Draw a well labelled nitrogen cycle in nature. (b) Describe one biological and one physical method of conversion of nitrogen to forms like nitrates and nitrities. OR (a) Draw a labelled carbon cycle in nature. (b) Describe briefly two process by which carbon dioxide is returned back to the atmosphere.

(i) Make a neat and labelled sketch of nitrogen cycle in nature. (ii) Describe in brief the role of nitrogen fixing bacteria and of lightenng in fixing atmospheric nitrogen. OR (i) Draw a neat labelled sketch of carbon cycle in nature. (ii) What is green house effect? How does carbon dioxide cause global warming in the atmosphere.

What is carbon cycle?

What is carbon cycle?