What percent of species become extinct when mass extinction occurs?
a)About 30%
b)About 50%
c)About 70%
d)About 80%

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.

Which type of respiration takes place when there is no oxygen present

Consider the following planned experiment. factor experimental group control group light exposure tots of sun tots of sun amount of water weekly weekly type of soil nutrient rich nutrient rich size of pot large which variable is being tested in this experiment? small a. size of pot b. type of soil c. light exposure d. amount of water