How carbon moves through living things and the air

Grade 7 Science Worksheet

Circle the best answer.

1. 1.

   Which process takes carbon dioxide out of the air, Ari?

   • Decay of fallen leaves
   • Burning fuels
   • Photosynthesis
   • Respiration by animals
2. 2.

   Which list holds processes that each add carbon dioxide to the air, Bo?

   • Photosynthesis, decay and burning
   • Photosynthesis and respiration
   • Respiration, decay and burning
   • Dissolving and photosynthesis
3. 3.

   In the diagram, carbon dioxide moves from the air into the sea. Which way does arrow X point, Jun?

   • From the ocean into the air
   • From the air into the ocean
   • From the ocean into the plants
   • From the fossil fuels into the sea
4. 4.

   NASA says the ocean now takes in more carbon dioxide than it gives off. Which way does the bigger arrow point, Kira?

   • From the air into the ocean
   • From the ocean into the air
   • Neither: they are the same size
   • From the ocean into the rock
5. 5.

   NOAA's carbon dioxide line dips each northern summer. Which explanation fits, Milo?

   • The ocean gives off carbon dioxide
   • Decay speeds up and adds more carbon dioxide
   • People stop burning fuels
   • Growing plants take in more carbon dioxide
6. 6.

   In northern winter, carbon dioxide in the air climbs. Which explanation fits, Noah?

   • Little growth, while decay keeps going
   • The ocean freezes over
   • Plants take in much more carbon dioxide
   • Snow makes carbon dioxide
7. 7.

   The yearly up-and-down in carbon dioxide follows the seasons. Which process mainly drives the summer dip, Pia?

   • Photosynthesis
   • Decay
   • Dissolving into the ocean
   • Respiration by animals
8. 8.

   A maple tree grows heavier each year. What happens to the carbon in the air when it does, Ren?

   • The air gains carbon
   • The tree makes brand-new carbon
   • Some moves out of the air into the tree
   • The tree pulls its carbon up from the soil
9. 9.

   After decomposers break down a fallen log, where is most of its carbon, Tala?

   • Gone: decomposers use it up
   • Inside the fossil fuels
   • Back in the air as carbon dioxide
   • Turned into energy and gone
10. 10.

    In a food web, energy flows on and leaves as heat. What happens to the carbon atoms, Zee?

    • They leave as heat, like energy
    • They are used up at each step
    • They are recycled again and again
    • They stay locked in the plants for good