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?

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

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

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

   A plant does photosynthesis in sunlight and respiration day and night. On a sunny day, what is true about its carbon dioxide, Esme?

   • It uses no carbon dioxide
   • It takes in more than it gives out
   • It does just respiration
   • It gives out more than it takes in
4. 4.

   Follow the arrows in the diagram. Where can carbon from burned fuel end up, Luz?

   • Back in the fuel
   • In the air, and some in the ocean
   • In the ocean first, then the fuel
   • In the Sun
5. 5.

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

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

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

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

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

   • Respiration by animals
   • Dissolving into the ocean
   • Photosynthesis
   • Decay
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?

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

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

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