Question

name: melissa garcia date: 10/7/05 period: _ environmental science cycles in ecosystems, (day 2 of 2) carbon cycle: 1. how do plants use carbon dioxide in the carbon cycle? 2. what process do animals and humans use to release carbon dioxide into the atmosphere? 3. how does carbon from dead plants and animals return to the soil or air? 4. what role do oceans play in the carbon cycle? 5. how do human activities, like burning fossil fuels, affect the carbon cycle? nitrogen cycle: 6. why is nitrogen important for living things? 7. how do nitrogen - fixing bacteria help plants? 8. what happens during the process of nitrification? 9. how do animals get the nitrogen they need? 10. how do human activities, like using fertilizer, affect the nitrogen cycle?

Explanation:

1. Plants use carbon dioxide in the carbon - cycle through photosynthesis, where they convert it into organic compounds using sunlight and release oxygen.
2. Animals and humans release carbon dioxide into the atmosphere through cellular respiration, which breaks down glucose to produce energy, carbon dioxide, and water.
3. Decomposition by bacteria and fungi breaks down dead plants and animals, releasing carbon back into the soil as organic matter or into the air as carbon dioxide.
4. Oceans act as a carbon sink, absorbing carbon dioxide from the atmosphere and storing it as dissolved inorganic carbon or in marine organisms.
5. Burning fossil fuels releases large amounts of stored carbon as carbon dioxide into the atmosphere, increasing the concentration of greenhouse gases and disrupting the carbon - cycle.
6. Nitrogen is important for living things as it is a key component of amino acids, which are the building blocks of proteins, and nucleic acids like DNA and RNA.
7. Nitrogen - fixing bacteria convert atmospheric nitrogen into ammonia or other nitrogen - containing compounds that plants can use to build proteins and other essential molecules.
8. During nitrification, ammonia is first oxidized to nitrite by ammonia - oxidizing bacteria, and then nitrite is further oxidized to nitrate by nitrite - oxidizing bacteria.
9. Animals get the nitrogen they need by consuming plants or other animals that contain nitrogen - rich compounds.
10. Using fertilizers adds large amounts of nitrogen to the soil. This can lead to nitrogen runoff into water bodies, causing eutrophication, and also increases the amount of nitrogen in the atmosphere through processes like denitrification.

Answer:

1. Through photosynthesis to convert it into organic compounds.
2. Cellular respiration.
3. By decomposition by bacteria and fungi.
4. Act as a carbon sink.
5. Release large amounts of stored carbon as carbon dioxide into the atmosphere.
6. It is a key component of amino acids and nucleic acids.
7. Convert atmospheric nitrogen into usable nitrogen - containing compounds for plants.
8. Ammonia is oxidized to nitrite and then to nitrate.
9. By consuming plants or other animals.
10. Add large amounts of nitrogen to the soil, leading to issues like eutrophication and changes in atmospheric nitrogen levels.