Mass extinctions of marine species are believed to have been caused by which event? a. asteroids hitting the earth c. volcanoes erupting b. heavy rains and flooding d. ultra violet rays select the best answer from the choices provided a b c d

Where in the body can you find chemoreceptors? a. on the skin and ears, to detect pressure, touch, motion, and sound b. on the retina, to detect a single photon of light c. on the skin, to detect temperature or specific chemicals d. on the tongue and in the nose, to detect taste or odor

What are some natural processes that represent physical and chemical changes?

What is a photon? a. part of a ribosome b. a light particle c. a carbon dioxide molecule d. part of a chloroplast b.a light particle