The Earth can be divided into four main layers: the solid crust on the outside, the mantle, the outer core and the inner core. Out of them, the mantle is the thickest layer, while the crust is the thinnest layer.
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These fossils are very useful for us because we can use them to date the layers of rock that they are found in. Fossils that can be used in this way are called index fossils, and rock layers with the same index fossils in them can be correlated. Not my answer, link here for full
http://peter-mulroy.squarespace.com/correlating-rock-layers/
Answer:
Bacterial plasmid are easily gotten from commercial suppliers, controlled to produced recombinant plasmits through the process of inserting foreing DNA, before it is introduced into bacterial cells.
Bottom-producers (plants) 1000
Primary consumers (herbivores) 100
Secondary consumers 10
Tertiary consumers (top) 1
