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

   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 0 units
   • A net change of +240 units
   • A net change of −50 units
   • A net change of −70 units
5. 4.

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

   • 36 percent
   • 44 percent
   • 25 percent
   • 0 percent
6. 5.

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

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

7. 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.

8. 6.

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

   • Line 2: decomposers move the carbon on, to the air or the soil
   • Line 1: fallen leaves hold no carbon that decomposers can use
   • Line 3: decomposers take in carbon dioxide and make new carbon
   • No line has a flaw, since decomposers destroy remains and their carbon

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 1: carbon dioxide cannot dissolve in ocean water
    • No line has a flaw, since phytoplankton make new carbon from the water
    • 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
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?

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

    • 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
    • Disagree: the carbon moves on, as carbon dioxide or as carbon in the soil
13. 10.

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

    • 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
    • Disagree: the ocean releases carbon dioxide to the air but takes no carbon in