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

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 12 units, because decomposers return the leaves’ carbon to the air
   • About 12 units, because photosynthesis in the fallen leaves gives off carbon dioxide
   • About 1 unit, because decomposers destroy the carbon in the leaves
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 returns to the air within the same year, since limestone is a fast store
   • It turns into new carbon in the rock, since rock forms carbon
   • It stays out of the ocean cycle, since limestone forms on land
   • It leaves the fast cycle and can stay stored in limestone for millions of years

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.

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

   • 36 percent
   • 25 percent
   • 0 percent
   • 44 percent
7. 5.

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

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

8. Use this

   Flow diagram of the carbon cycle (model, not to scale), a meadow. Boxes: atmosphere; grass; grasshopper; decomposers. Arrows: from atmosphere to grass, process photosynthesis, carries carbon dioxide; from grass to atmosphere, process cellular respiration, carries carbon dioxide; from grass to grasshopper, process passes to, carries carbon in plant material; from grass to decomposers, process passes to, carries carbon in fallen leaves; from decomposers to atmosphere, process decomposition, carries carbon dioxide. Notebook, 3 lines. Line 1: In light, the grass takes in carbon dioxide by photosynthesis. Line 2: The grass is a plant, so it never releases carbon dioxide. Line 3: Carbon in the grass can pass to a grasshopper.

9. 6.

   Noah reads a notebook entry about the meadow diagram. Which line has a flaw?

   • Line 1: photosynthesis is the process that releases carbon dioxide
   • Line 3: carbon cannot pass to a grasshopper, which makes its own carbon
   • Line 2: grass cells also respire, so they release carbon dioxide
   • No line has a flaw, since respiration is a process of animals

10. Use this

    Flow diagram of the carbon cycle (model, not to scale), a meadow. Boxes: atmosphere; grass; grasshopper; decomposers. Arrows: from atmosphere to grass, process photosynthesis, carries carbon dioxide; from grass to atmosphere, process cellular respiration, carries carbon dioxide; from grass to grasshopper, process passes to, carries carbon in plant material; from grass to decomposers, process passes to, carries carbon in fallen leaves; from decomposers to atmosphere, process decomposition, carries carbon dioxide. Notebook, 3 lines. Line 1: Fallen leaves pass carbon to decomposers. Line 2: Decomposers destroy that carbon, so it leaves the cycle. Line 3: Decomposers release carbon dioxide to the air.

11. 7.

    Pia reads a notebook entry about the meadow diagram. Which line has a flaw?

    • Line 3: decomposers take in carbon dioxide and make new carbon
    • Line 2: decomposers move the carbon on, to the air or the soil
    • Line 1: fallen leaves hold no carbon that decomposers can use
    • No line has a flaw, since decomposers destroy remains and their carbon
12. 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: photosynthesis is the process that releases carbon dioxide
    • Agree: trees make new carbon, so they give no carbon back to the air
    • Disagree: tree cells also respire and release carbon dioxide
    • Agree: animals and decomposers release carbon dioxide, but plants do not
13. 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?

    • Agree: decomposers destroy the carbon in the leaf while they break it down
    • Disagree: the carbon moves on, as carbon dioxide or as carbon in the soil
    • Disagree: decomposers make new carbon, so more carbon is there afterward
    • Agree: the carbon turns into oxygen gas, which leaves the leaf
14. 10.

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

    • Disagree: carbon dioxide dissolves in the ocean and leaves it in a steady exchange
    • Disagree: the ocean makes new carbon and passes it up to the air
    • 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