The diagram shows the fossils found in different layers of a rock. A diagram labeled Fossil Layers is shown. The topmost layer is labeled A and shows the skeleton of a fish, the second layer from the top is labeled B and shows a shell, the third layer from the top is labeled C and shows a fern leaf, and the lowermost layer shows an oak leaf In which layer is the oldest fossil found? Layer A Layer B Layer C Layer D

/the trachea, commonly known as the windpipe

. ph changes the ability of them he enzyme to dissolve in water.

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.

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