Exam (elaborations) GIZMOS Food Chain Gizmos

Exam (elaborations) GIZMOS Food Chain Gizmos Vocabulary: consumer, ecosystem, energy pyramid, equilibrium, food chain, population, predator, prey, producer Prior Knowledge Questions (Do these BEFORE using the Gizmo.) The Food Chain Gizmo™ shows a food chain with hawks, snakes, rabbits, and grass. In this simulation, the hawks eat snakes, the snakes eat rabbits, and the rabbits eat grass. 1. Producers are organisms that do not need to eat other organisms to obtain energy. A. Which organism is a producer in this food chain? The grass is a producer in this food chain. B. Where does the producer get its energy? The producer gets its energy from the sun. 2. Consumers must eat other organisms for energy. Which organisms are consumers in this food chain? The hawks, snakes, and rabbits are the consumers in this food chain. Gizmo Warm-up The SIMULATION pane of the Gizmo shows the current population, or number, of each organism in the food chain. 1. What are the current populations of each organism? Hawks: 42 Snakes: 278 Rabbits: 2,566 Grass: 27,300 2. Select the BAR CHART tab, and click Play ( ). What do you notice about each population as time goes by? The population doesn’t change much. If populations don’t change very much over time, the ecosystem is in equilibrium. 3. Notice the populations decrease as you go from the bottom of the food chain to the top. Why This study source was downloaded by from CourseH on :27:18 GMT -05:00 This study resource was shared via CourseH GIZMOS Food Chain Gizmos do you think this is so? I think this is so because the lower levels need a big enough population to give energy to the one below them. This diagram, showing decreasing populations at each level, is called an energy pyramid. This study source was downloaded by from CourseH on :27:18 GMT -05:00 This study resource was shared via CourseH Activity A: Predator-prey relationships Get the Gizmo ready: ● Click Reset ( ). ● Check that the BAR CHART tab is selected. Question: Predators are animals that hunt other animals, called prey. How do predator and prey populations affect one another? 1. Observe: Run the Gizmo with several different starting conditions. You can use the + or – buttons to add or remove organisms, or you can choose Diseased from the dropdown lists. 2. Form hypothesis: How do you think predator and prey populations affect one another? I think that the predator and prey populations affect one another because if one was diseased, for example the rabbits, the snakes could get a disease from the rabbit and then that will go towards the hawks. 3. Predict: Based on your hypothesis, predict how changing the rabbit population will affect the other organisms at first. Write “Increase” or “Decrease” next to each “Prediction” in the table. Change Grass Snakes Hawks Doubling rabbit population Prediction: Increase Prediction: Increase Prediction: Increase Result: Decrease Result: Increase Result: Increase Halving rabbit population Prediction: Decrease Prediction: Decrease Prediction: Decrease Result: Increase Result: Decrease Result: Decrease 4. Test: Add rabbits until the population is about twice as large as it was (200% of balance). Click Play, and then Pause ( ) after approximately ONE month. Next to each “Result” line in the table, write “Increase” or “Decrease.” Click Reset and then halve the rabbit population (50% of balance). Record the results for this experiment in the table as well. A. How did doubling the rabbit population affect the grass, snakes, and hawks at first? Doubling the rabbit population affected the grass by decreasing it because of the immense growth of the rabbit population. It affected the snakes by increasing the population as well as the hawks population. B. How did halving the rabbit population affect the grass, snakes, and hawks at first