Question

1. what roles do photosynthesis & cellular respiration play in the carbon & oxygen cycles?

1. why are bacteria so important for the nitrogen cycle?

1. what is the name of the process where nitrogen is converted into nitrates?

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Explanation:

Question 4

Photosynthesis takes in \( \ce{CO_2} \) (carbon source) and releases \( \ce{O_2} \), contributing to oxygen production and carbon fixation. Cellular respiration uses \( \ce{O_2} \) and releases \( \ce{CO_2} \), recycling carbon and consuming oxygen, thus balancing gas levels in the cycles.

Bacteria perform key nitrogen - cycle processes: nitrogen fixation (convert \( \ce{N_2} \) to ammonia), nitrification (ammonia to nitrites/nitrates), and denitrification (nitrates back to \( \ce{N_2} \)). These processes make nitrogen available to plants (via fixation/nitrification) and return it to the atmosphere (via denitrification), enabling nutrient cycling.

The process of converting nitrogen (usually \( \ce{N_2} \)) into nitrates (\( \ce{NO_3^-} \)) occurs in two main steps: first, nitrogen fixation (to ammonia) and then nitrification (ammonia to nitrites to nitrates). The overall process that results in nitrate production from atmospheric nitrogen involves these bacterial - mediated steps, and the specific process of converting nitrogen (in forms like ammonia) to nitrates is called nitrification (with the first step of nitrogen fixation preceding it in the pathway from \( \ce{N_2} \) to nitrates). However, if we consider the direct conversion of nitrogen (after fixation to ammonia) to nitrates, the process is nitrification. But if we consider the entire pathway from \( \ce{N_2} \) to nitrates, it involves nitrogen fixation followed by nitrification. But the process that specifically converts nitrogen - containing compounds (after fixation) into nitrates is nitrification.

Answer:

• Photosynthesis: Absorbs \( \boldsymbol{\ce{CO_2}} \) (from the atmosphere/ecosystem) to produce glucose (fixing carbon) and releases \( \boldsymbol{\ce{O_2}} \) (into the atmosphere), replenishing oxygen and reducing atmospheric \( \ce{CO_2} \) in the carbon - oxygen cycles.
• Cellular Respiration: Uses \( \boldsymbol{\ce{O_2}} \) (from the atmosphere) to break down glucose, releasing energy, \( \boldsymbol{\ce{CO_2}} \) (back to the atmosphere/ecosystem), and water. This recycles carbon (as \( \ce{CO_2} \)) and consumes oxygen, maintaining the flow of carbon and oxygen between organisms and the environment.

Question 5