Ascientist suspects that the food in an ecosystem may have been contaminated with radioactive nitrogen over a period of months. which of the following substances could be examined for radioactivity to test the hypothesis
a. the cell walls of the plants growing in the ecosystem
b. the muscles of humans living in the ecosystem
c. the sugars produced during photosynthesis by plant growing in the ecosystem
d. the phospholipids in the cell membranes fo organisms living in the ecosystem