Nitrogen fixation, N2 --> NH3+, is not something that plants to by themselves but some plants have bacteria that does this. I believe that pea plants have these, but I'm not 100% sure.
Yes, it is believed that one of the first Greek ancient astronomers, and the first notable Greek philosopher, was Thales, who lived at the beginning of the 6th Century BCE.
<span>If Noam chooses a filter, it might be more effective than a screen. After using it for a while, though, he will have to replace it, which could be expensive. A screen might be less effective, but it can be cleaned instead of replaced.</span>
