During cellular respiration, every living thing in this food web uses gas and releases back into the environment.

a. carbon dioxide: oxygen
b. oxygen: carbon dioxide
c. carbon dioxide: hydrogen
d. carbon dioxide: water vapor

Which of the following is a cost of urbanization? a-cities can provide a high standard of living. b-cities are hubs of entertainment and education. c-paving over land changes the environment. d-job opportunities are greater in urban centers.

Which of the following typically characterizes a tropical rainforests

The cluster of developing cells from conception until birth is called an