Basics About Life

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What is life?

1. Cells organized structure and function: single-celled organisms, muscle cells
2. DNA self replication
3. Energy capture & transformation = Photosynthesis and Respiration
4. Maintenance of favorable internal conditions = Homeostasis
5. Reproduction
6. Evolution (Antibiotic resistance)

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What sustains life?

• flow (one-way) of energy (high-quality): sunlight or geothermal energy
• cycling of matter: carbon, water, oxygen, nutrients - each stage of cycle results in loss of energy, usually as heat
• gravity-it's the law!

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Ecosystem

Closely interdependent species and their physical environment in a specific place.
• Flow of Energy
• Cycling of Nutrients

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Ecosystem Boundaries

Populations have optimum ranges

How these ranges overlap is partly what determines the species composition of ecosystems. Ranges are commonly but not always determined by physical conditions (temperature, light, water, etc.). The distribution of some species may be determined by the distribution of others.

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Ecosystems have structure

Transfer of nutrients and energy (energy is lost at every step as heat) Different ecosystems have different structures: trophic levels.
• producers (plants, photosynthesis)
• herbivores (plant eaters)
• carnivores (herbivore eaters)
• decomposers (bacteria +)

LINK: Understanding Lake Ecology
LINK: Ecosystem Description (NOAA)

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