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9th grade · Science · Unit 13 of 28

Ecosystem Dynamics

Carrying capacity, energy pyramids and human impacts.

What your child practices

Practices carrying capacity, energy flow and the 10% rule, how ecosystems respond to disturbance, and evaluating solutions to human impacts, using New York's Adirondack lakes, Great Lakes and Hudson River as examples.

New York State Learning Standards learning standard: HS-LS2-1; HS-LS2-4; HS-LS2-6; HS-LS2-7 · carrying capacity, energy flow, ecosystem stability and reducing human impacts on biodiversity

How we explain it

Children can open this short lesson before they practice.

  1. Populations level off at carrying capacity on a logistic growth curve.
  2. Producers are the first trophic level; about 10% of energy passes up each level.
  3. Invasive species like zebra mussels outcompete native species for food.

Example: Producers store 5000 kJ. About how much reaches the primary consumers? About 10% passes on. 10% of 5000 is 500. Answer: 500 kJ

Ecosystem Dynamics in New York

In the New York State Learning Standards, this is unit 13 of 28 in 9th grade Science, after Science & Society and before Body Systems & Homeostasis.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: New York State Education Department (NYSED)

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    Which solution to help river herring and shad in the Hudson River's streams is backed by evidence?

    • Draining wetlands
    • Adding more barriers
    • Removing old dams and restoring habitat
    • Paving stream banks

  2. Question 2

    Why are there fewer top predators than herbivores?

    • Predators eat less
    • Predators live longer
    • Herbivores are smaller
    • Less energy reaches higher levels

  3. Question 3

    A logistic growth curve levels off at…

    • carrying capacity
    • the starting population
    • infinity
    • zero

  4. Question 4

    If producers capture 10,000 kJ, about how much reaches the secondary consumers?

    • 100 kJ
    • 10 kJ
    • 5000 kJ
    • 1000 kJ

  5. Question 5

    Producers are at which trophic level?

    • The third
    • The first
    • The second
    • The top

  6. Question 6

    Overfishing can cause…

    • colder water
    • fish populations to grow
    • more biodiversity
    • populations to collapse

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