Cycles within Ecosystems: Answers

Which type of organism converts nitrogen in the air into nitrates in the soil? Where are these organisms found?

Nitrogen-fixing bacteria can convert atmospheric nitrogen into nitrates in the soil, which plants can then absorb. These type of bacteria are found either in the soil or living inside the roots of certain plants.

Which type of organism converts nitrates in the soil into nitrogen in the air? Under which conditions does this reaction occur.

Denitrifying bacteria convert nitrates in the soil back into atmospheric nitrogen. This process is harmful to plants as it reduces the amount of ntirates they can absorb and convert into protein. It happens under water-logged conditions so it is good practice to allow soil to drain properly to prevent this process happening.

Describe how the nitrogen compounds in dead leaves are turned into nitrates in the soil.

Decomposers (such as bacteria and fungi) break down proteins and convert them into ammonia (a nitrogen-containing compound). Ammonia forms ammonium ions in the soil.

Explain how deforestation can increase the amount of carbon dioxide in the atmosphere.

Trees absorb carbon dioxide for photosynthesis, so deforestation can increase the amount of carbon dioxide in our atmosphere.

How can deforestation change the amount of precipitation in an area? What effect could this have on other plant life?

Transpiration of water from the leaves of trees can cause clouds to accumulate over areas where there is a high density of trees, such as tropical rainforests. Clearing the rainforest by deforestation can reduce cloud formation in the area and reduce levels of precipitation. Since plants need water for photosynthesis, this can affect other plant life as they will carry out less photosynthesis.