2.6.7ESS SL20 flashcards

How humans change energy and matter

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Card 1 of 202.6.7

Question

State the “big idea” linking energy and matter in ecosystems.

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All 20 Flashcards — How humans change energy and matter

Card 1concept

Question

State the “big idea” linking energy and matter in ecosystems.

Answer

Ecosystems depend on energy input (photosynthesis) and recycling of matter (nutrients). Human actions can reduce productivity, remove biomass, and disrupt cycles.

💡 Hint

Energy in + matter recycled

Card 2concept

Question

State one way fossil fuel use can reduce productivity.

Answer

Air pollutants damage plant tissues and climate change alters rainfall/temperature, reducing photosynthesis and productivity.

💡 Hint

Pollution + climate stress reduce photosynthesis

Card 3concept

Question

State one way air pollution can reduce photosynthesis.

Answer

Pollutants can damage leaves or block stomata, reducing CO2 uptake and lowering photosynthesis.

💡 Hint

Leaf damage → lower photosynthesis

Card 4concept

Question

State one activity that reduces producers.

Answer

Deforestation or urbanisation removes producers (plants) from ecosystems.

💡 Hint

Deforestation/urbanisation

Card 5definition

Question

Define primary productivity.

Answer

Primary productivity is the rate at which producers create biomass using photosynthesis.

💡 Hint

Rate of biomass by producers

Card 6concept

Question

Explain why removing producers reduces biomass.

Answer

With fewer producers, less energy is captured by photosynthesis and less biomass is created at the base of the food web.

💡 Hint

Less photosynthesis → less biomass

Card 7concept

Question

Explain why deforestation increases atmospheric CO2.

Answer

Trees store carbon. When forests are removed (often burned or decomposed), stored carbon is released as CO2 and less is absorbed.

💡 Hint

Less storage + less uptake

Card 8concept

Question

Explain how climate change can reduce primary productivity.

Answer

Heat stress and altered rainfall increase drought and reduce plant growth, so less biomass is produced.

💡 Hint

Heat/drought reduce growth

Card 9concept

Question

Explain why harvesting reduces nutrient recycling.

Answer

Biomass is removed, so nutrients leave the ecosystem instead of being returned to soil by decomposition.

💡 Hint

Nutrients removed with biomass

Card 10concept

Question

Explain how urbanisation reduces productivity.

Answer

Built surfaces replace producers and fragment habitats, so less photosynthesis occurs and food webs weaken.

💡 Hint

Replace producers with buildings

Card 11concept

Question

Explain how deforestation disrupts the water cycle.

Answer

Fewer trees means less transpiration and often less local rainfall, increasing drying and erosion risk.

💡 Hint

Less transpiration → less rainfall

Card 12concept

Question

Explain how deforestation reduces energy flow in food webs.

Answer

Removing producers reduces photosynthesis, so less energy becomes biomass at the base of the food web.

💡 Hint

Fewer producers → less energy entry

Card 13concept

Question

Explain what is meant by “biomass is exported” in agriculture.

Answer

Harvest removes biomass from the ecosystem, so energy and nutrients leave instead of being recycled by decomposition.

💡 Hint

Harvest removes nutrients

Card 14concept

Question

State one way agriculture disrupts nutrient cycling.

Answer

Harvest removes biomass, so fewer nutrients return to soil through decomposition, increasing reliance on fertilisers.

💡 Hint

Harvest removes nutrients

Card 15concept

Question

State two cycles commonly altered by human land use.

Answer

Human activities can alter nutrient cycles (nitrogen/phosphorus), the carbon cycle, and the water cycle.

💡 Hint

N/P + carbon + water

Card 16concept

Question

Explain how agriculture can lower ecosystem resilience.

Answer

Monocultures simplify food webs and reduce biodiversity, so the system is less able to recover from disturbance.

💡 Hint

Lower biodiversity → lower resilience

Card 17concept

Question

State the exam-ready two-part phrase for human impacts on ecosystems.

Answer

Humans reduce energy flow (lower productivity) and disrupt matter storage/transfer (alter cycles).

💡 Hint

Energy flow + matter cycling

Card 18concept

Question

State the best cause → effect chain for “harvesting reduces nutrient recycling”.

Answer

Harvest removes biomass → fewer nutrients return via decomposition → soil fertility declines unless fertiliser is added.

💡 Hint

Remove biomass → fewer nutrients returned

Card 19concept

Question

State the strongest exam link for deforestation (two parts).

Answer

Deforestation reduces energy input (fewer producers) and reduces matter storage (less carbon in biomass/soil).

💡 Hint

Energy input + matter storage

Card 20concept

Question

State the exam-ready link: producers removed → what happens?

Answer

When producers are removed, less energy enters food webs, biomass decreases, and ecosystem stability often falls.

💡 Hint

Less energy in → weaker food web

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