An earthworm lives and reproduces in the soll. Through its feeding, excretion and tunneling activities, the worm adds nutrients and allows air to enter the soil.
Together, these statements describe the earthworm's *
a. Habitat
b. Nutrition
c. Environment
d. Niche

American scientist, linus pauling, was one of many scientists racing to discover the molecular structure of dna. pauling initially thought that the molecule was a triple helix. later, james watson and francis crick unveiled their double helix model, which turned out to be an accurate description of the molecule's shape. why did watson and crick succeed when pauling failed?