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Flip to reveal answersDefine energy efficiency in a food chain.
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All 25 Flashcards — Energy input and release
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Question
Define energy efficiency in a food chain.
Answer
Energy efficiency is the percentage of energy transferred from one trophic level to the next.
💡 Hint
Percent transferred
Question
Define photosynthesis.
Answer
Photosynthesis is the conversion of light energy into chemical energy stored in glucose.
💡 Hint
Light → glucose
Question
State the process that traps solar energy as chemical energy.
Answer
Photosynthesis.
💡 Hint
Light trapped
Question
Define cellular respiration.
Answer
Cellular respiration is the process that releases energy from glucose in cells, usually using oxygen.
💡 Hint
Releases energy from glucose
Question
State two reasons energy is lost between trophic levels.
Answer
Energy is lost as heat from respiration and in waste/uneaten material (faeces, bones, plant fibre).
💡 Hint
Heat + waste/uneaten
Question
State the approximate value of the 10% rule.
Answer
On average, about 10% of energy at one trophic level becomes biomass available to the next level.
💡 Hint
~10% passes on
Question
Define incomplete consumption.
Answer
Incomplete consumption is when not all parts of an organism are eaten, so energy in those parts is not transferred.
💡 Hint
Not all eaten
Question
State what happens to energy during respiration.
Answer
Some energy is transferred to ATP for life processes and a significant amount is released as heat.
💡 Hint
Heat released
Question
State the process that releases energy from glucose in cells.
Answer
Cellular respiration.
💡 Hint
Releases energy
Question
State the inputs and outputs of photosynthesis.
Answer
Inputs: carbon dioxide and water. Outputs: glucose and oxygen.
💡 Hint
CO2 + H2O → glucose + O2
Question
Define inefficient digestion.
Answer
Inefficient digestion is when not all ingested food is absorbed; energy leaves the body as faeces.
💡 Hint
Not all absorbed
Question
State where photosynthesis occurs in plant cells.
Answer
Photosynthesis occurs in chloroplasts.
💡 Hint
Chloroplasts
Question
State whether cellular respiration occurs in plants.
Answer
Yes. Plants respire continuously to release energy for life processes.
💡 Hint
Plants respire
Question
Explain why energy transfer efficiency is low.
Answer
Energy is used for respiration, movement and maintenance and is lost as heat and waste rather than becoming new biomass.
💡 Hint
Heat + waste
Question
State two major pathways for energy loss between trophic levels.
Answer
Heat loss from respiration and losses in waste/uneaten material.
💡 Hint
Heat + waste
Question
State the approximate proportion of energy transferred to the next trophic level.
Answer
About 10% (order-of-magnitude).
💡 Hint
~10%
Question
Explain why photosynthesis is important for energy flow in ecosystems.
Answer
It traps solar energy and stores it as chemical energy in biomass that can be transferred through food chains.
💡 Hint
Traps sunlight into biomass
Question
Explain how low efficiency affects food chain length.
Answer
Low transfer efficiency leaves too little energy at higher trophic levels to support many levels, so chains are short.
💡 Hint
Too little energy higher up
Question
State the main form in which energy leaves organisms during transfer.
Answer
Energy leaves mainly as heat released during respiration.
💡 Hint
Heat from respiration
Question
Explain why respiration reduces energy transfer between trophic levels.
Answer
Organisms use energy for metabolism and release much of it as heat, so less becomes new biomass available to the next level.
💡 Hint
Less biomass formed
Question
Explain why biomass generally decreases up a food chain.
Answer
Because only a small proportion of energy becomes new biomass at each trophic transfer; most is lost as heat and waste.
💡 Hint
Less energy for growth
Question
Explain why diets based on lower trophic levels can be more energy efficient.
Answer
Fewer trophic transfers means less energy is lost as heat before reaching humans.
💡 Hint
Fewer transfers
Question
State how energy enters most ecosystems.
Answer
Energy enters mainly as sunlight and is captured by producers via photosynthesis.
💡 Hint
Sunlight captured
Question
Explain why higher trophic levels usually have lower biomass.
Answer
Less energy becomes new biomass at each transfer because most is lost as heat and waste, so biomass decreases at higher levels.
💡 Hint
Less energy for growth
Question
Explain how respiration illustrates the second law of thermodynamics.
Answer
Respiration releases heat, showing that energy transfers are inefficient and usable energy decreases.
💡 Hint
Heat = inefficiency
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Flows of energy and matter
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