How are atoms, elements and compounds related ?

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.

What would most likely happen if green plants were exposed to longer days of sunlight? a. the mitochondria would produce less energy . b. the chloroplasts would produce more energy. c. the cell wall would become thicker. d. the vacuoles would quickly shrink.b. the chloroplasts would produce more energy.

Substances that can pass through cell membranes by diffusion include a. na ions. b. proteins c. glucose. d. oxygen.