Geochemical Cycles , Symbiosis, & Population Growth

1. Geochemical Cycles , Symbiosis, & Population Growth

2. Biogeochemical Cycles of matter • Unlike energy, matter is constantly being recycled in an ecosystem in what are known as biogeochemical cycles. • Water Cycle: continuous flow of water on Earth: - Precipitation – rain, snow, sleet, hail - Evaporation – change of state from liquid to gas - Condensation – change of state from gas to liquid - Transpiration – evaporation of water from plant leaves - Respiration – release of water from animal breathing

3. Carbon – Oxygen Cycle The continuous flow of O2 & CO2 on Earth • Biological processes (photosynthesis, respiration, & decomposition) • Geochemical processes (volcanoes) • Human activity (burning of fossil fuels & deforestation)

4. Nitrogen Cycle: continuous flow of N on Earth. • Nitrogen fixation, denitrification, & human activities contribute • N is the most abundant gas in atmosphere (78%) • Nitrogen gas is unusable for plants, it must be “fixed” or changed into the nitrate or nitrite form by bacteria in the soil. Known as nitrogen fixation

5. Phosphorus Cycle • The continuous flow of phosphorus from land to water to organisms and back to land, • P is important in the production of DNA and RNA. • phosphorus is NOT found in the atmosphere. Found in rocks and minerals.

6. Symbiosis: Relationship between 2 species that benefits at least one of the species. • Mutualism – both organisms benefit. ex: lichens (fungus & algae); and bees pollinate flowers • Commensalism – one benefits; the other is neither helped nor harmed. ex: bird nest in a tree, clownfish in anemone • Parasitism – one benefits; the other is harmed. ex. fleas & ticks on a dog

7. 3 characteristics of a population: Growth Rate, • Population Density, & Geographic Distribution • 1. Geographic Distribution • Clumped Dispertion – far apart in some areas, close together in some areas. • Uniform Dispertion – evenly spread out • Random Dispersion – no pattern

8. 2. Population Density: the number of individuals per unit area Methods of conducting a population survey: Direct observation, indirect observation, sampling, & catch and release.

9. 3. Growth Rate (includes immigration & emigration): the difference between birth and death rate of a population. • Immigration – movement of individuals of a population moving into an area. (I = in) • Emigration – movement of individuals of a population out of an area. (E = exit)

10. - Logistical Growth: population growth slows or stops as resources become less available; resulting in an S-shaped curve. - Exponential Growth: population increases rapidly in a few generations under ideal conditions in which birth rates exceed death rates. - Carrying Capacity: largest population an environment can support.

11. Limiting Factors to Population Growth: • Density Dependent: Competition, predation, parasites, & disease. -Competition: the struggle among organisms for basic needs (food, water, shelter, space, mates) -Predation: Predator-Prey Relationships. • Density Independent: weather conditions, natural disasters, seasonal cycles, & human activities.