Which of the following is NOT an unresolved question about the origins of early life? a. Whether the early atmosphere was methane rich b. Whether early cells formed in hot or cold environments c. Whether early cells had a membrane surrounding them d. Whether the first life was extraterrestrial

The answer here is D, and it's kind of obvious. But you probably already knew the answer and are just doing this for piece of mind.

Explanation: Just the fact that we don't know whether or not there even is extraterrestrial life rules out every other answer, without even needing to go in depth.

(Okay, I read your question completely wrong, it's asking for which one of these has been solved isn't it?)

This is tough because all of these other than D have been figured out. Go with the methane atmosphere then.

just go with your heart buddy

step 1 ammonium can be absorbed by plants, but some is converted into nitrates which are better for plants to absorb. this is called nitrification. 2. step 2 the deer eats the plants and uses the nitrogen-containing proteins for cell growth. 3. step 3 bacteria in the soil conduct nitrogen fixation to convert nitrogen gas from the atmosphere into ammonium. 4. step 4 some of the nitrates are absorbed back into plants, but denitrification breaks down the nitrates into nitrogen gas released back into the atmosphere. 5. step 5 nitrogen is found in the urine, which gets broken down into ammonium through the process of ammonification. 6. step 6 plants absorb the ammonium and begin assimilation, the process to add the nitrogen to protein.