The carbon cycle across rock, ocean, air and life

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Where carbon is and how fast it moves (NASA)

   Part of the cycle	NASA figure
   Carbon stored in rocks	about 65,500 billion metric tons
   Carbon through the slow cycle each year	10 to 100 million metric tons
   Carbon through the fast cycle each year	1,000 to 100,000 million metric tons
   Volcano CO₂ each year	130 to 380 million metric tons
   Human CO₂ each year	about 30 billion tons

2. 1.

   Using the table, the fast cycle's low end is 1,000 million metric tons a year and the slow cycle's high end is 100 million. How many times larger is the fast end, by Bo's math?

   • 1,100 times
   • 900 times
   • 10 times
   • 0.1 times
3. 2.

   Compare the slow cycle's low end (10 million metric tons a year) with the fast cycle's high end (100,000 million). How many times larger is the fast flow, by Esme's math?

   • 100 times
   • 99,990 times
   • 10,000 times
   • 1,000 times
4. 3.

   NASA (2009): people released about 8.4 billion tons of carbon from fossil fuel, and about half is removed by the fast cycle each year. About how much stays in the air, by Jun's math?

   • About 16.8 billion tons
   • About 4.2 million tons
   • About 4.2 billion tons
   • About 0.42 billion tons

5. Carbon's slow path

   Rain, rock, river, sea floor, limestone, volcano.

6. 4.

   In the ocean, calcium ions combine with bicarbonate. What forms and builds up as limestone, by Kira's reading (NASA)?

   • Pure carbon dioxide
   • Sodium chloride
   • Calcium carbonate
   • Methane gas
7. 5.

   NASA: about 80% of carbon-containing rock forms from calcium carbonate. Where does the other 20% come from, by Luz's reading?

   • Volcanic ash that holds no carbon from living things
   • Carbon that fell to Earth from space as meteorites over long ages
   • Ice that froze CO₂ from the air into stone
   • Carbon from living things buried in mud, making rock like shale
8. 6.

   What returns carbon from sea-floor rock to the air over millions of years, by Milo's reading (NASA)?

   • Fish eat the limestone and breathe its carbon out
   • Waves wash the limestone up into the clouds
   • Plates carry it down, the rock heats, and volcanoes vent CO₂
   • Winter cold squeezes CO₂ out of the sea-floor rock each year
10. 7.

    What mainly adds extra CO₂ to the air today, by Noah's reading (NASA)?

    • Growing crops, which give off CO₂ in sunlight
    • People breathing out more than in the past
    • Volcanoes erupting more often than in the past
    • Burning fossil fuels, with some from clearing land
11. 8.

    Why does burning fossil fuels change the carbon cycle, by Pia's reading (NASA)?

    Use the picture in question 7.

    • It moves carbon from the air back into rock quickly
    • It makes brand-new carbon that was not on Earth at any time before
    • It slows the fast cycle down to the pace of rock
    • It moves carbon from the slow cycle into the fast cycle quickly
12. 9.

    Rain, rock, river, sea floor, limestone, volcano. Without people, how would carbon in fossil fuels reach the air, by Ren's reading (NASA)?

    • Within a lifespan, as animals breathe
    • Slowly, through volcanic activity over millions of years
    • Within a year, through plant growth
    • Each day, as waves wash it out of rock
13. 10.

    NASA: over millennia, the ocean will absorb up to 85% of the extra carbon. Why does it take so long, by Ari's reading?

    • Fish must eat the carbon before it dissolves
    • It depends on water moving from the surface to the depths
    • CO₂ cannot dissolve in salt water
    • The ocean is already full of carbon and can take in no more of it