Energy pyramids: how much energy reaches each level

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   Use the table

   Card (real data, from OpenStax Biology 2e). Biomass in the English Channel.

   level	biomass (g/m²)
   producers (phytoplankton)	4
   primary consumers (zooplankton)	21

2. 1.

   Jun reads real biomass data from the English Channel. Which statement about the pyramids is right?

   • Both pyramids are inverted here, since the primary consumers hold more than the producers
   • The biomass pyramid is upright here, and the energy pyramid is the inverted one
   • The biomass pyramid is inverted here, but a pyramid of energy is upright
   • Both pyramids are upright, since biomass must fall at each level of a chain
3. 2.

   Kira reads the English Channel data again. How can 4 g/m² of producers support 21 g/m² of primary consumers?

   • Energy passes up with no loss, so a higher level can hold more than the one below
   • The primary consumers make their own energy from light, so they need few producers
   • The phytoplankton reproduce quickly, so the small mass is replaced fast
   • The primary consumers send their energy back to the producers each day to use again
4. 3.

   Luz reads real counts for a temperate forest. Why can 200 trees support 150,000 primary consumers?

   • Energy grows at each step, so the insects hold more energy than the trees below them
   • The insects send their energy back to the trees, who use it again to grow
   • Large trees capture a lot of energy, so a few can support many small organisms
   • Each tree holds very little energy, so a few trees could support just a few insects
5. 4.

   Energy pyramid (real data, from OpenStax Biology 2e), not to scale, 4 steps from the bottom. Unit: kcal/m²/yr. Milo compares Silver Springs with the 10 percent rule of thumb. Which statement fits the three steps?

   • The three steps each pass exactly 10 percent, so the rule of thumb matches the data
   • Each step passes a larger percent than the step before it, rising up the pyramid
   • The first two steps pass more than 10 percent and the third passes less
   • The three steps each pass less than 10 percent, so the rule of thumb is too high

6. Use the table

   Card (real data, from OpenStax Biology 2e). The first step at Silver Springs.

   measure	percent passed up
   TLTE given by OpenStax	about 14.48
   from the pyramid numbers 3,368 and 20,810	about 16.2

7. 5.

   Pia reads two values for the first step at Silver Springs. Which statement is best?

   • The values are close but not equal, and both are above 10 percent
   • TLTE is the percent of the energy that is lost as heat at the first step
   • Together they show that exactly 10 percent of the energy passes up the pyramid
   • The 16.2 must be wrong, since TLTE is a fixed value of 14.48 percent
8. 6.

   not to scale; 3 steps from the bottom. Notebook, 3 lines. Ren reads a notebook entry about the pyramid. Which line has a flaw?

   • Line 1: the primary consumers should hold more energy than the producers do
   • Line 3: each step should pass its energy up in full to the next step
   • No line has a flaw, since energy lost at a step is gone for good
   • Line 2: the missing 9,000 kJ was used or lost as heat, not destroyed

9. Use this

   Energy pyramid (model data), not to scale, 3 steps from the bottom. Unit: kJ. Bottom step: producers (grass), 10,000 kJ. Second step: primary consumers (grasshoppers), 1,000 kJ. Top step: secondary consumers, 100 kJ. Decomposers break down the wastes and remains from the levels. Notebook, 3 lines. Line 1: Producers pass energy to the primary consumers. Line 2: Decomposers break down remains and return matter to the soil. Line 3: They also return the energy, so energy is reused like matter.

10. 7.

    Zee reads a notebook entry about decomposers. Which line has a flaw?

    • Line 2: decomposers do not return any matter to the soil or the ecosystem
    • No line has a flaw, since energy is reused like matter in an ecosystem
    • Line 1: producers do not pass any energy on to the primary consumers
    • Line 3: matter returns, but energy leaves as heat and is not reused

11. Use this

    Energy pyramid (model data), not to scale, 4 steps from the bottom. Unit: kJ. Bottom step: producers (grass), 10,000 kJ. Second step: primary consumers (grasshoppers), 1,000 kJ. Third step: secondary consumers, 100 kJ. Top step: tertiary consumers, 10 kJ.

12. 8.

    Ari's friend says the top level holds the most energy because it is at the top. Which reply is best?

    • Disagree: the four steps hold equal energy, since nothing is lost on the way up
    • Disagree: each step up holds less, since heat is lost at each step
    • Agree: energy builds up as it passes up each step, so the top holds the most
    • Disagree: the middle steps hold the most energy, with less at the top and bottom
13. 9.

    Bo's friend says a food chain could have any number of levels if the sun keeps shining. Which reply is best?

    • Disagree: heat is lost at each step, so a long chain runs out of energy
    • Disagree: the energy is destroyed at the top level, which ends the chain
    • Agree: decomposers return energy to the top level, so it can be reused
    • Agree: energy passes up unchanged, so any number of levels can be supported
14. 10.

    Energy pyramid (real data, from OpenStax Biology 2e), not to scale, 4 steps from the bottom. Unit: kcal/m²/yr. Esme's friend says the 10 percent rule means exactly 10 percent passes up in every real ecosystem. Which reply is best?

    • Disagree: it is a rough guide; Silver Springs passes 16.2, 11.4 and 5.5 percent
    • Disagree: the real percents are higher than 10 at the first step and at each step after
    • Agree: a real food chain passes the same percent from one step to the next
    • Agree: Silver Springs passes about 10 percent at the first step and at each step after