The ultimate source of energy to support most life on earth is see concept 10.1 (page 189)
a) geothermal heat
b) sunlight
c) photosynthetic plants
d) the carbon cycle
e) chemosynthetic microbes

How do you know that the plant cells in these two images have different jobs, or functions? a. because all plant cells serve different functions b. because they are two different colors c. because their dna are different d. because their structures are different

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

Ivan is looking at a cross section of a stem taken from a vascular plant. he sees two different types of vascular tissue: the xylem, which is closer to the center of the stem, and the phloem, located around the xylem, closer to the outside of the stem. how do these two structures work together in a living plant?