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Earth as a System: Energy, Matter, and Life
Life on Earth is powered by a constant flow of energy and matter. The Sun is the main source of energy. In addition, the Earth’s hot interior and...
Patterns in Life: Diversity and Classification
The Earth is home to an enormous variety of life forms. This immense variety of living organisms is known as biodiversity. Biodiversity is...
Reproduction: How Life Continues
Every organism has a definite life span - it is born, grows, matures, reproduces and eventually dies. Reproduction is a biological process by which...