Aim How does energy flow in an ecosystem

Aim: How does energy flow in an ecosystem? Look at the pond ecosystem § We know all living things need energy in order to survive. But……. u Where does the energy to support life originally come from? u Which type of living things can trap this energy? Regents Biology

u u u How does energy flow in an ecosystem? Does all the energy get transferred or some of it is loss? These are some interesting questions we can ask ourselves. Regents Biology

Flow of Matter and Energy in Ecosystems § Review § Food chains: the stepwise flow of energy and nutrients through an ecosystem. u u from plants (producers) to herbivores (primary consumers) to carnivores (secondary and higher-level consumers berries → mice → black bear Regents Biology

Food chains § Feeding relationships Tertiary consumer Top carnivore Level 4 all food chains start with energy from Secondary consumer the sun Level 3 Carnivore u first level of all food Primary consumer chains is plants Level 2 Herbivore u most food chains usually go up only 4 or 5 levels Level 1 Producer u all levels connect to Bacteria decomposers u Regents Biology Decomposers Sun Fungi

Loss of Energy § Loss of energy between levels of food chain u To where is the energy lost? The cost of living!� 17% growth only this energy moves on to the next level in the food chain Regents Biology energy lost to daily living 33% cellular respiration 50% waste (feces)

Trophic levels represent links in the chain § Each organism in a food chain represents a feeding step, or trophic level, in the passage of energy and materials. Regents Biology

Trophic Levels Regents Biology

q In this food chain, what the producer? q What is the first level consumer? q What is the second level consumer? q Is the hawk the 3 rd leve consumer? Explain. Regents Biology

Review: Food Webs § network of interconnecting food chains u It is a more realistic view of the trophic structure of an ecosystem than a food chain Regents Biology

Energy and trophic levels: Ecological pyramids § show energy flows through an ecosystem. § illustrates that the amount of available energy decreases at each succeeding trophic level. § The total energy transfer from one trophic level to the next is only about ten percent Regents Biology

But what about nutrients? § Energy flows through but nutrients cycle u u nutrients must be recycled to be available for the next generation n u t r i e n t s decomposers return nutrients to the soil after creatures die § fungi § bacteria Regents Biology decomposers

Energy flows Nutrients cycle sun 2006 -2007 Regents Biology secondary consumers (carnivores) decomposers lo en ss er of gy of s gy s lo er en primary consumers (herbivores) lo en ss o er f gy producer s (plants) soil

Ecosystem inputs constant energy flows input of through energy nutrients cycle Matter Don’t forget cannot be thecreated laws ofor destroyed Physics! nutrients can only cycle Regents Biology biosphere inputs § energy § nutrients

Energy Pyramid § level D = producers § level C = primary consumers § level B= secondary consumers § level A = tertiary consumers secondary consumers primary consumers producers Regents Biology

Energy Pyramid § What happens to the total amount of available energy as you move up the trophic level? tertiary consumers secondary consumers primary consumers producers Regents Biology

Energy Pyramid § Which trophic level contains the most amount of available energy? § Which trophic level contains the least amount of available energy? Regents Biology

Summary Question § How does energy flow in an ecosystem? Regents Biology

Critical Thinking Question § What happens to an ecosystem if there is a drought (prolong period without rain) ? Explain. Must be as least 1 paragraph. Regents Biology

Critical Thinking-Application Question § As the number of people in poor countries begin to become wealthy, they start to demand consume more meat based diet. How will this effect the environment and you? Regents Biology

Let’s Check for Understanding Regents Based Questions 1. Base your answer to the question on the diagram below and on your knowledge of biology. What is an appropriate title for this diagram? A. Energy Flow in a Community B. Ecological Succession C. Biological Evolution D. A Food Chain Regents Biology

Let’s Check for Understanding Regents Based Questions 2. One arctic food chain consists of polar bears, fish, seaweed, and seals. Which sequence demonstrates the correct flow of energy between these organisms? A. seals → seaweed → fish → polar bears B. fish → seaweed → polar bears → seals C. seaweed → fish → seals → polar bears D. polar bears → fish → seals → seaweed Regents Biology

Let’s Check for Understanding Regents Based Questions The diagram below shows a food chain. 3. If the population of bobcats decreases, what will most likely be the long-term effect on the rabbit population? A. It will increase, only. B. It will decrease, only. C. It will increase then decrease. D. It will decrease then increase. Regents Biology

Let’s Check for Understanding Regents Based Questions 4. Which sequence shows a correct pathway for the flow of energy in a food chain? A. bacteria – grass – fox – owl B. grass – grasshopper – frog – snake C. fungi – beetle – algae – mouse D. algae – snake – duck – deer Regents Biology

Let’s Check for Understanding Regents Based Questions Base your answer to the question on the diagram of a food web and on your knowledge of biology. 5. If the population of mice is reduced by disease, which change will most likely occur in the food web? A. B. C. D. The cricket population will increase. The snake population will increase. The grasses will decrease. The deer population will decrease. Regents Biology

Let’s Check for Understanding Regents Based Questions Base your answer to the question on the diagram of a food web and on your knowledge of biology. 6. What is the original source of energy for this food web? A. B. C. D. chemical bonds in sugar molecules enzymatic reactions the Sun chemical reactions of bacteria Regents Biology