The digestive system breaks down materials into substances the body can use. what structure inside the cell is most similar to the digestive system in humans?
a. cytoplasm
b. lysosme
c. nucleolus
d. ribosome

Consider the model of the oxygen cycle on earth. the majority of earth's oxygen reservoirs are found in the a) atmosphere. b) biosphere. c) hydrosphere. d) lithosphere.

One important development during the 3rd trimester that will insulate the infant against changes in temperature is a. the deposition of fat under the skin b. the closing of the septum between c. the atria of the heart d. the beginnings of lung functioning e. the beginnings of light and sound sensing

Guard cells control which event? the growth of plants capture of solar energy gas exchange in leaves water absorption in roots