Quizlet is a great flashcard site that helps you create your own flashcards, and provides you with some great ready-made flashcards as well. As an ESL teacher, I find it to be very useful, especially for students who are not native speakers and do not have anybody at home to help them with their vocabulary.
The atmosphere, the ocean, and the terrestrial biosphere. Carbon can be found in the earths oceanic and continental crust in different types of stones as well as in the soil from the decay of organic matter.
The biosphere is a system characterized by the continuous cycling of matter and an accompanying flow of solar energy in which certain large molecules and cells are self-reproducing. Water is a major predisposing factor, for all life depends on it. The elements carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur, when combined as proteins, lipids, carbohydrates, and nucleic acids, provide the building blocks, the fuel, and the direction for the creation of life.