Ecosystem Energy Budgets: GPP, NPP and Transfer Efficiency · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Where the Energy Goes

Science · Organisms & Life Processes · ages 17-18
Name ______________________   Date ____________

  1. How do you calculate net primary production?

    • GPP minus respiration
    • GPP plus respiration
    • Respiration minus GPP

  2. What is gross primary production (GPP)?

    • The energy herbivores gain from food
    • The total chemical energy producers fix
    • The heat lost by the top predator

  3. What does the ten percent rule say?

    • All energy moves up unchanged
    • About a tenth becomes new biomass above
    • Producers keep ten percent for themselves

  4. Grass holds 20000 units and new rabbit tissue holds 2000. What is the percentage transfer?

    Answer: ______________

  5. A field has GPP of 20000 units and producers respire 8000 units. What is the NPP?

    Answer: ______________

  6. A rabbit eats grass but most of it never becomes rabbit. Where does the rest go?

    • It returns to the soil as glucose
    • It waits in the grass for winter
    • It leaves as heat, waste, and uneaten parts

  7. A fox eats rabbits, voles, and grasshoppers. Rabbits decline. Why does the web view matter here?

    • The fox must starve at once
    • Grass stops growing without rabbits
    • The fox still eats voles and grasshoppers, so effects spread several ways

  8. A student says most of the energy at one level becomes biomass at the next. This claim is true.

    Circle one:   True   False

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Answer key

For grown-ups. Fold this page away before handing over the rest.

Where the Energy Goes W1-mt_D81CKcOdBI-s1

  1. GPP minus respiration · Plants burn some fixed energy staying alive, so NPP is what remains after respiration.
  2. The total chemical energy producers fix · GPP is everything the producers fix, before their own respiration takes a share.
  3. About a tenth becomes new biomass above · Roughly one tenth of the energy at a level is built into new biomass at the next level.
  4. 10 · 2000 divided by 20000 times 100 gives a 10 percent transfer.
  5. 12000 · NPP equals 20000 minus 8000, which is 12000 units.
  6. It leaves as heat, waste, and uneaten parts · Respiration burns most to heat, some leaves in urine and faeces, and roots go uneaten.
  7. The fox still eats voles and grasshoppers, so effects spread several ways · A web shows the cross links, so one loss ripples through several feeding paths at once.
  8. False · Only about a tenth moves up. The rest is lost to heat, waste, and uneaten parts.
Worksheet · LightMySky