Here are the step-by-step solutions for the questions in your worksheet:
1. Which of the following processes contributes to the carbon cycle?
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Reasoning: The carbon cycle involves moving carbon between the atmosphere, living things, and the earth.
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Combustion (burning things like wood or fossil fuels) releases carbon dioxide into the air.
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Respiration (breathing) releases carbon dioxide when animals and plants break down food for energy.
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Photosynthesis takes carbon dioxide out of the air so plants can make food.
* Since all three are key parts of how carbon moves around, they all contribute.
*
Answer: all of the above
2. The source of carbon to plants in the carbon cycle is
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Reasoning: Plants need carbon to build their stems, leaves, and roots. They get this carbon from the air, not from the soil or rocks directly. They absorb a gas called carbon dioxide ($CO_2$) through tiny holes in their leaves to perform photosynthesis.
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Answer: carbon dioxide
3. The conversion of nitrates to nitrogen is called
*
Reasoning: In the nitrogen cycle, different bacteria perform specific jobs:
* *Nitrogen fixation* turns atmospheric nitrogen into ammonia.
* *Nitrification* turns ammonia into nitrates.
* *Denitrification* is the process where bacteria turn nitrates back into nitrogen gas, which is released back into the atmosphere. This completes the cycle.
*
Answer: Denitrification
4. The role of bacteria in the carbon cycle occurs in which process below?
*
Reasoning: Bacteria act as "decomposers" in nature. When plants and animals die, bacteria break down their bodies (organic compounds). This process releases the carbon stored in those bodies back into the soil and atmosphere as carbon dioxide. Photosynthesis is done by plants/algae, and combustion is usually physical burning.
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Answer: Decomposition of organic compounds
5. In the carbon cycle, the human body returns carbon to the atmosphere through
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Reasoning: Humans take in carbon by eating food. To use that food for energy, our cells perform a process called cellular respiration. A waste product of this process is carbon dioxide gas, which we breathe out (exhale) into the atmosphere.
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Answer: respiration
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Final Answer:
1. all of the above
2. carbon dioxide
3. Denitrification
4. Decomposition of organic compounds
5. respiration
Parent Tip: Review the logic above to help your child master the concept of carbon and nitrogen cycle worksheet.
