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Grade 7 · Science · Unit 4 of 10

Cycles & Succession

Matter cycles; land regrows

What your child practises

How water, carbon and nitrogen are cycled through ecosystems, why cycling supports sustainability, and the difference between primary and secondary succession.

Nunavut Curriculum approved guide: Nunavut adaptation of Alberta Science 7–9 (2003), Unit A: Interactions and Ecosystems · cycles of matter and how ecosystems change over time

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

    A wildfire burns a forest. The next spring, fireweed is already growing. Why so soon?

    • Succession cannot happen after a fire
    • Fireweed seeds fall from clouds
    • Roots, seeds and soil survived the fire
    • The fire created new soil from rock

  2. Question 2

    Water vapour cools and turns into tiny droplets in clouds. This is called…

    • precipitation
    • condensation
    • evaporation
    • runoff

  3. Question 3

    Which statement about succession is true?

    • It never happens after fires
    • It happens only in water
    • It always ends in a desert
    • Communities change over time in a fairly predictable pattern

  4. Question 4

    A farmer plants a different crop in a field each year. How can this keep the soil healthy?

    • It removes all decomposers
    • Different crops use and return different nutrients
    • It stops the water cycle
    • It adds new matter to Earth

  5. Question 5

    Why do pioneer species usually come first?

    • Animals plant them on purpose
    • They can survive harsh conditions with little soil and few nutrients
    • They need rich soil
    • They are the largest plants

  6. Question 6

    Which process puts carbon dioxide into the air?

    • condensation
    • photosynthesis
    • evaporation
    • respiration by living things

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