Darwin gathered many ideas from various sources over the next 20 years. Identify what Darwin learned from each source.

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

Why do leaves change color in the fall? green pigments break down and no longer mask the color of chlorophyll. chlorophyll breaks down and no longer masks the colors of other pigments. red- and yellow-colored pigments grow and mask green-colored chlorophyll. green-colored chlorophyll breaks down and turns red and yellow.

What did not occur in the proterozoic eon a)the oxygen levels increase greatly in the atmosphere,b)the emergence of the eukarya , c)muti cella’s eukaryotic organisms began to diversify,d)anaerobic bacteria kept thriving with more oxygen