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Flip to reveal answersDefine net primary productivity (NPP).
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All 10 Flashcards — Soil and productivity
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Question
Define net primary productivity (NPP).
Answer
NPP is the rate at which plants produce biomass after accounting for respiration.
💡 Hint
Photosynthesis minus respiration.
Question
Soil quality directly affects which productivity measure?
Answer
Net primary productivity (NPP).
💡 Hint
Plants/biomass.
Question
Name two soil factors that can limit productivity.
Answer
Low nutrient availability (e.g., N or P limiting) and low water-holding capacity (drought stress) can limit productivity.
💡 Hint
Think nutrients + water.
Question
Name three key factors linking soil to productivity.
Answer
Nutrients, water availability (water-holding capacity), and aeration (oxygen for roots).
💡 Hint
Nutrients + water + oxygen.
Question
Why does soil aeration affect productivity?
Answer
Roots need oxygen for respiration; poor aeration (waterlogging/compaction) reduces root function and plant growth, lowering NPP.
💡 Hint
Roots need O2.
Question
Name one soil organism group and its function.
Answer
Decomposers (bacteria/fungi) break down dead matter and release nutrients.
💡 Hint
Decomposers = recycling.
Question
How do mycorrhizae help plant productivity?
Answer
They increase root surface area and improve uptake of water and mineral nutrients, supporting plant growth and NPP.
💡 Hint
Fungi help roots.
Question
How do decomposers increase soil fertility?
Answer
Decomposers break down dead organic matter and release mineral nutrients back into the soil for plants to absorb.
💡 Hint
Recycle nutrients.
Question
What is the role of nitrogen-fixing bacteria in productivity?
Answer
They convert atmospheric N2 into plant-available nitrogen compounds (often in legume root nodules), reducing nitrogen limitation and increasing plant growth.
💡 Hint
N2 → usable nitrogen.
Question
Exam technique: what must each point include in a 4–7 mark “soil and productivity” answer?
Answer
A clear cause-effect link from a soil property to plant growth to increased NPP.
💡 Hint
Property → growth → NPP.
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Topic 5.1 hub
Soil systems
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