What process takes carbon dioxide from the air and makes it available to land living animals?
  • Photosynthesis
  • Respiration
  • Lightning strikes
  • Burning fossil fuels
Which two natural processes return carbon dioxide to the air?
  • Photosynthesis and respiration
  • Respiration and decomposition
  • Digestion and eating
  • Using nuclear fuels
Which human activity returns carbon dioxide to the air?
  • Generating electricity
  • Driving cars
  • Flying planes
  • All of the above
Why do fossil fuels have a high carbon content?
  • They are made in swamps
  • They are made from organisms that were once alive
  • They are made from limestone
  • They were made in fires started by lightning millions of years ago
Which of the following is a problem caused by humans burning fossil fuels?
  • A hole in the ozone layer
  • Deforestation
  • Global warming
  • All of the above
How might burning fossil fuels be creating global warming?
  • Because fossil fuels will be all used up in a few decades
  • Because burning fossil fuels is a very dangerous process
  • Because fossil fuels are not compatible with the new biofuels
  • Because burning fossil fuels adds CO2 to the atmosphere faster than it can be removed
How is carbon in plants passed on to the rest of the cycle?
  • Only death and decay
  • Only by being eaten
  • Through food webs
  • By forming coal
Carbonate rocks lock carbon out of the cycle for millions of years. Which of the following does put CO from these rocks back into the current carbon cycle?
  • Grinding them up into small particles to use for making roads
  • Manufacturing cement
  • Heat from volcanoes
  • When they are subducted during plate tectonics
Why do waste materials and dead plants or animals decay?
  • They are broken down by microorganisms
  • They get rained on
  • They slowly sink into the ground
  • Sunlight breaks down their chemicals
How is the CO from the air introduced into a food web?
  • Plants breathe it in and when an animal eats the plant, it eats the CO2 as well
  • It forms carbonate rocks that eventually come to the surface
  • Plants use the products of photosynthesis to manufacture carbohydrates, fats and proteins
  • Bacteria living in nodules on the root convert it into plant food
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