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

Which of the following shows the correct order in which light information travels through the eye? (2 points) lens, pupil, retina, optic nerve pupil, lens, retina, optic nerve pupil, lens, optic nerve, retina lens, pupil, optic nerve, retina

Astudent reads the following text in a science book: scientific evidence tells us that the cause of earths four seasons is the tilt of earth as it revolves around the sound the student is instructed to illustrate this information in a science book. how will the student illustrate winter in the northern hemisphere? a.earths northern hemisphere will tilt away from the sun. b. earths northern hemisphere will tilt toward the sun. c.earths orbit will be farther away than from the sun d. earths southern hemisphere will tilt away from the sun.

Give two examples of what would occur if one of the pairs did not match or had an extra chromosomes. explain how this might occur, and if it would be dangerous to the individual. fast.