Ecology: nutrient cycles — KCSE Biology

KCSE Biology · 78 practice questions · 3 syllabus objectives

26 easy26 medium26 hard

What You'll Learn

Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.

Describe the nitrogen cycle with named organisms

Describe the carbon cycle

Ecology: nutrient cycles

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easySHORT ANSWER2 marks

Name two human activities that increase the concentration of carbon dioxide in the atmosphere. (2 marks)

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Part (a) — 2 marks

Burning of fossil fuels for energy production (1 mk)

Deforestation for agricultural expansion or urban development (1 mk)

easySHORT ANSWER2 marks

State two ways in which carbon is stored in living organisms. (2 marks)

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Part (a) — 2 marks

In the form of carbohydrates such as starch in plants (1 mk)

In the form of proteins and lipids in animal tissues (1 mk)

easySHORT ANSWER3 marks

State three processes through which carbon is absorbed by living organisms from the atmosphere. (3 marks)

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Part (a) — 3 marks

Photosynthesis by green plants, converting CO₂ into glucose (1 mk)

Absorption by phytoplankton in aquatic ecosystems during photosynthesis (1 mk)

Dissolution in water bodies where CO₂ is absorbed by aquatic plants (1 mk)

Name two processes in the nitrogen cycle that involve the conversion of nitrogen compounds back into atmospheric nitrogen. (4 marks)

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