Biology  by Bradford
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8.2 Energy Flow Through Ecosystems: revision map

The subtopic in the middle and five tasks round it: label a diagram, complete two tables, put a process in order and fill 12 gaps. Every box rests on a learning objective of the topic in the AP Biology course and exam description. Type into the blanks and check them, or print it on A4, Letter or A3 with an answer key.

Unit 8 practice questionsThe whole Unit 8 map

Topic 8.2

Energy Flow Through Ecosystems

AP Biology · Unit 8 EcologyName

8.2.A, 8.2.B, 8.2.C, 8.2.DAn energy pyramid

123456
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6

8.2.B, 8.2.CProductivity

Producers capture energy as gross primary productivity (GPP). They use part of it in respiration (R), and the rest, the net primary productivity, is stored in new biomass, and is what is available to consumers: NPP = GPP − . Ecosystems with high NPP, such as tropical rain forests and estuaries, support the most life. Energy flows one way through an ecosystem and is lost as heat, while matter such as carbon and nitrogen is .

8.2.AEnergy up the levels

Trophic levelEnergy available (kJ)Left for next level
Producers10 000
Primary consumers1 000100
Secondary consumers10
Tertiary consumers101

About 10% of the energy at one level is passed to the next. The rest is lost as , used in respiration, or left in waste and uneaten parts, so food chains seldom have more than four or five levels.

Topic 8.2Energy Flow Through Ecosystems

8.2.DStaying warm costs energy

EndothermEctotherm
Body heat fromits own metabolismthe environment
Energy needed for foodlow
Activity in the coldstays activebecomes sluggish
Examplemammals and birdsreptiles and most fish

Because endotherms spend most of their energy on keeping warm, only a small share goes to growth, so they make less new biomass from the same food than an ectotherm.

8.2.AEnergy in a food chain

Number the steps in order.

  1. A herbivore eats the producer and gets part of its stored energy.
  2. Sunlight is captured by producers in photosynthesis.
  3. A carnivore eats the herbivore.
  4. At each step much of the energy is lost as heat.
  5. Decomposers break down dead material and waste at every level.
Word bank 1 000100decomposersheathighprimary consumersproducersRrecycledsecondary consumerstertiary consumers

Answer key

Every box on the sheet with its gaps filled in, as the subtopic reads in full.

  1. LabelAn energy pyramid

    1. producers
    2. primary consumers
    3. secondary consumers
    4. tertiary consumers
    5. heat
    6. decomposers

  2. TableEnergy up the levels

    Trophic levelEnergy available (kJ)Left for next level
    Producers10 0001 000
    Primary consumers1 000100
    Secondary consumers10010
    Tertiary consumers101

    About 10% of the energy at one level is passed to the next. The rest is lost as heat, used in respiration, or left in waste and uneaten parts, so food chains seldom have more than four or five levels.

  3. GapsProductivity

    Producers capture energy as gross primary productivity (GPP). They use part of it in respiration (R), and the rest, the net primary productivity, is stored in new biomass, and is what is available to consumers: NPP = GPP − R. Ecosystems with high NPP, such as tropical rain forests and estuaries, support the most life. Energy flows one way through an ecosystem and is lost as heat, while matter such as carbon and nitrogen is recycled.

  4. TableStaying warm costs energy

    EndothermEctotherm
    Body heat fromits own metabolismthe environment
    Energy needed for foodhighlow
    Activity in the coldstays activebecomes sluggish
    Examplemammals and birdsreptiles and most fish

    Because endotherms spend most of their energy on keeping warm, only a small share goes to growth, so they make less new biomass from the same food than an ectotherm.

  5. OrderEnergy in a food chain

    1. Sunlight is captured by producers in photosynthesis.
    2. A herbivore eats the producer and gets part of its stored energy.
    3. A carnivore eats the herbivore.
    4. At each step much of the energy is lost as heat.
    5. Decomposers break down dead material and waste at every level.