Question

1. organisms that can fix atmospheric nitrogen into chemical compounds. carbon bacteria a nitrogen fixing bacteria pioneer species primary species 6. a process in which nitrogen is cycled between the atmosphere, bacteria and other organisms. bacteria cycle a oxygen cycle nitrogen cycle water cycle 7. when the settlers arrived in new england, many forests were turned into fields. eventually, some fields were abandoned and then grew back into forests. this is best described as primary succession a secondary succession pioneer succession tertiary succession

Explanation:

• Question 5: Nitrogen - fixing bacteria have the ability to convert atmospheric nitrogen (\(N_2\)) into chemical compounds (such as ammonia \(NH_3\)) that plants can use. Carbon bacteria are related to carbon - related processes (e.g., decomposition of organic carbon), pioneer species are the first species to colonize barren areas, and primary species is not a standard ecological term in this context.
• Question 6: The nitrogen cycle specifically describes the cycling of nitrogen between the atmosphere (as \(N_2\)), bacteria (which can fix nitrogen, nitrify, or denitrify), and other organisms (plants and animals that use nitrogen - containing compounds). The bacteria cycle is not a standard named cycle, the oxygen cycle is about the movement of oxygen, and the water cycle is about the movement of water.
• Question 7: Secondary succession occurs in an area where there was previously an ecosystem (in this case, the field was part of an area that was originally a forest). Primary succession occurs in a completely barren area (e.g., newly formed volcanic rock). Pioneer succession is not a standard term (pioneer species are part of succession, but not a type of succession itself), and tertiary succession is not a recognized ecological term.

Answer:

1. B. nitrogen fixing bacteria
2. C. nitrogen cycle
3. B. Secondary succession