Welcome! First we will look at the quizzes – we will grade them in class – then we will start the new Challenge (3). Hmwk: Complete Part 3 if needed
Challenge 3 – Part 1 Food Chains Today we are going to learn how energy and molecules move throughout an ecosystem – by studying food chains and food webs. What do you know about food chains. Take a moment to think about this and prepare to share with the class.
What is an omnivore? Pygmy Marmoset Margay Golden Headed Lion Tamarin
Time LapseDecomposition of detritus • Video 1 – Gecko • Video 2 – Rabbit
Each of these food chains includes five trophic levels. What is a trophic level?
Food Web • What is the difference between a food chain and a food web?
Energy Pyramid • What is the source of all energy on Earth? • Where is the most energy available in a food chain? • 10% of the energy at each level is passed on to the next level. 90% is lost as heat or used by the organisms to carry out their normal life functions. • Why is there less biomass at each level of the food chain? • What is biological magnification?
How does energy flow through an ecosystem? • Energy enters an ecosystem as light, is converted to chemical energy by producers, and exits the ecosystem as heat. • Energy is not recycled within an ecosystem, but flows through it and out. • Chemicals such as carbon can be recycled between the living and nonliving parts of ecosystems and the biosphere.
Who produces the living matter or biomass of an ecosystem? • An ecosystem's primary productivity is the rate at which the producers build biomass. Factors such as rainfall and temperature influence productivity. • Which of these biomes has the greatest primary productivity?
What is an Energy Pyramid? • Notice in Figure 36-7 that the amount of energy available to the top-level consumer is tiny compared to that available to primary consumers. For this reason, it takes a lot of vegetation to support higher trophic levels. • Why are most food chains limited to three or four levels?
What is a biomass pyramid? • A biomass pyramid represents the actual biomass (dry mass of all organisms) in each trophic level in an ecosystem. Most biomass pyramids narrow sharply from the producer level at the base to the top-level consumers at the peak (Figure 36-8). • Why would there be less biomass at the tertiary consumer level?
Final Wrap Up – Can you answer the original question? • How do energy and molecules move through ecosystems?