How is nitrogren 'fixed' into a useable form for plants? a through action of bacteria & lightning
b only through action of bacteria
c only through lightning
d photosynthesis

Sediment layers stop lateral spreading when: they encounter a barrier they encounter an opposing current they run out of additional sedimentary material

Food webs - transferring energy and matter from one level to another. here you see four food webs. one or more are incorrect. which food web(s) show the correct sequence of organisms, from start to top level consumer? a) a b) d c) c d) a and d

Which characteristics are typical of a human population in the postindustrial stage?