How living things move carbon

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Esme’s class covers a sealed jar so no light enters. The jar holds a plant, soil and decomposers. What happens to the carbon dioxide in the jar over the next day?

   • It falls, because the plant keeps taking in carbon dioxide without light
   • It rises, because respiration and decomposition continue while photosynthesis stops
   • It rises, because photosynthesis gives off carbon dioxide in the dark
   • It stays the same, because the plant does not release carbon dioxide

2. Read this first

   Use the table

   Card (model data). Carbon dioxide released from fallen leaves in 4 weeks (read about only)

   jar	carbon dioxide released (units)
   jar A: soil with fungi and bacteria	12
   jar B: soil with no fungi or bacteria	1

3. 2.

   Bo’s class compares two jars of fallen leaves. Jar C is set up like jar A. Which prediction for jar C’s carbon dioxide in 4 weeks is best?

   • About 1 unit, because decomposers make new carbon, not carbon dioxide
   • About 1 unit, because decomposers destroy the carbon in the leaves
   • About 12 units, because decomposers return the leaves’ carbon to the air
   • About 12 units, because photosynthesis in the fallen leaves gives off carbon dioxide
4. 3.

   Kira reads that tiny ocean organisms build shells and the shells settle on the seafloor each year. Which prediction fits the carbon in those shells?

   • It turns into new carbon in the rock, since rock forms carbon
   • It returns to the air within the same year, since limestone is a fast store
   • It leaves the fast cycle and can stay stored in limestone for millions of years
   • It stays out of the ocean cycle, since limestone forms on land

5. Use the table

   Card (model data). Carbon moving in one year (units of carbon)

   flow	from and to	units per year
   photosynthesis	air to plants and algae	120
   respiration by plants and animals	living things to air	70
   decomposition	remains to air	50
   dissolving	air to ocean	40
   leaving the water	ocean to air	40

6. 4.

   Jun reads a model ledger of yearly carbon flows. What is the net change in the carbon of the air over the year?

   • A net change of −70 units
   • A net change of 0 units
   • A net change of +240 units
   • A net change of −50 units
7. 5.

   Luz uses the same ledger. What share of the carbon entering the air each year comes from the ocean?

   • 44 percent
   • 36 percent
   • 0 percent
   • 25 percent
8. 6.

   Milo uses the same ledger. How much carbon is taken out of the air over the year, in total?

   • 40 units
   • 120 units
   • 160 units
   • 320 units

9. Use this

   Notebook, 3 lines. Line 1: Carbon dioxide from the air dissolves in ocean water. Line 2: Carbon dioxide also leaves the water for the air. Line 3: So the ocean is not part of the carbon cycle.

10. 7.

    Ren reads a notebook entry about the bay diagram. Which line has a flaw?

    • Line 3: the ocean exchanges carbon dioxide with the air, so it takes part
    • Line 2: carbon dioxide leaves the water by photosynthesis in the air
    • No line has a flaw, since phytoplankton make new carbon from the water
    • Line 1: carbon dioxide cannot dissolve in ocean water
11. 8.

    Tala’s friend says a forest only takes carbon from the air, since plants do photosynthesis and never release carbon dioxide. Which reply is best?

    • Disagree: tree cells also respire and release carbon dioxide
    • Agree: trees make new carbon, so they give no carbon back to the air
    • Agree: animals and decomposers release carbon dioxide, but plants do not
    • Disagree: photosynthesis is the process that releases carbon dioxide
12. 9.

    Zee’s friend says that once a leaf falls and decomposers break it down, its carbon is gone for good. Which reply is best?

    • Disagree: the carbon moves on, as carbon dioxide or as carbon in the soil
    • Agree: decomposers destroy the carbon in the leaf while they break it down
    • Agree: the carbon turns into oxygen gas, which leaves the leaf
    • Disagree: decomposers make new carbon, so more carbon is there afterward
13. 10.

    Ari’s friend says the ocean is too separate from the air to matter in the carbon cycle. Which reply is best?

    • Disagree: the ocean releases carbon dioxide to the air but takes no carbon in
    • Agree: the ocean is cut off from the air, so it plays no part in the cycle
    • Disagree: the ocean makes new carbon and passes it up to the air
    • Disagree: carbon dioxide dissolves in the ocean and leaves it in a steady exchange