UNIT: Ecology How does energy and matter cycle through an ecosystem? Standard Element: SB4.b Explain the flow of matter and energy through ecosystems by Arranging components of a food chain according to energy flow. Comparing the quantity of energy in the steps of an energy pyramid. Explaining the need for cycling of major nutrients (C, O, H, N,).

Matter and Energy Transfer in an Ecosystem Matter (nutrients) are constantly cycled through an ecosystem Energy from the sun enters an ecosystem through the producers. Energy flows from the producers to the primary consumers, to the secondary consumers and to the tertiary consumers and eventually to the decomposers Energy is either used, transferred or lost as heat, but cannot be cycled!

Food chains A food chain is a simple model that shows how energy flows in 1 direction through an ecosystem. Food chains always begin with producers Producers (autotrophs, plants) can make their own food using photosynthesis

Food Webs A food web is a complex model that shows how energy flows in many directions through an ecosystem. Food webs always begin with producers on the bottom Producers (autotrophs, plants)can make their own food using photosynthesis

Food Chains and Webs show: Energy flows from the producers, to the primary consumers, then secondary consumers, then tertiary consumers Arrows always point from prey to predator because it shows where energy is transferred to. Trophic levels or feeding steps: 1st trophic level-Producers 2nd trophic level-Primary consumers 3rd trophic level- Secondary consumers 4th trophic level- Tertiary consumers

The Ecological Pyramids 1. Energy Pyramid Shows the decrease of energy at each trophic level. The total energy transfer up is about 10% Not all food that is eaten can be digested Some of the digested food is used as energy and some is lost as heat

The Ecological pyramids 2. Pyramid of numbers Shows the number of organisms on each trophic level Producers will always have the largest population size. 3. Biomass pyramid(living weight) Shows the mass of organisms on each trophic level Producers will always have the largest biomass

Nutrient Cycles in Ecosystems Nutrients are constantly cycled through an ecosystem in order to maintain homeostasis. Water Cycle: movement of water through an ecosystem Evaporation: liquid to gas Condensation: water vapor cools and gets packed to form clouds Precipitation: rain, snow, sleet, hail Transpiration: water released from plants Runoff: extra water collected in rivers and streams

Carbon Cycle in Ecosystems Carbon is most commonly found in the form of CO2 gas in the atmosphere Carbon released in the atmosphere by… Burning of fossil fuels (Combustion) Cellular respiration Decomposition Carbon is used by… 1. Photosynthesis

Nitrogen Cycle in Ecosystems Organisms need nitrogen to make proteins but we cannot use the nitrogen in the air SOOOO…… We depend on bacteria to fix it for us! Nitrogen fixation: bacteria living on the roots of plants absorb nitrogen in the atmosphere and convert it to a form that plants can use to make proteins Denitrification: Bacteria release nitrogen back into the atmosphere How do we get the nitrogen that we need? We get nitrogen by either eating the plants, or by eating the consumer that ate the plants