Cells contain a cell wall that is not found in cells.
a. animal, human
c. plant, animal
b. human, plant
d. animal, plant

How can scientists test their ideas about the origin of the universe if they can't physically interact with or study?

The ultimate purpose of respiration: a. inhale 02 and exhale co2 b. place oxygen in the lungs c. place oxygen in the blood d. deliver oxygen to every blood cell

Which of the following is not a technology that can be used to conserve resources? a. hydropower b. volcanic power c. natural gas d. geothermal select the best answer from the choices provided a b c d