Living World Review #2 1. Each of these organisms are found within Yellowstone National Park in the western United States. Use the following guidelines to create this food web and then answer questions 2-5. 1. Pond algae is eaten by mayflies and trout. 2. wheatgrass and sagebrush are eaten by elk, bison, hares, and deer mice. 3. Gray willow leaves are eaten by deer mice, elk, and bison. 4. Aspen trees are eaten by beavers. The leaves are eaten by elk. 5. Mayflies are eaten by ducks, bears, and deer mice. 6. The hare is eaten by coyotes, wolves, and foxes. 7. trout are eaten by hawks and bears. 8. Beavers are eaten by coyotes and gray wolves. 9. Ducks are eaten by red foxes and hawks 10. Deer mice are eaten by coyotes, red foxes, grizzly bears, and hawks 11. Elk and bison are eaten by coyotes and gray wolves. 12. Gray wolves may also feed on coyotes and red fox. 2. From the food web above, identify an organism that is: Carnivore Third Order Consumer Omnivore Autotroph Primary Consumer Red Fox, Hawk, Gray Wolf, Coyote, Bear Coyote, Hawk, Red Fox Bear, Deer Mouse Wheat Grass, Aspen, Grey Willow, Sage Brush, Algae Hare, Trout, Beaver, Mayfly, Deer Mouse, Elk, Bison A Secondary AND Tertiary Consumer Red Fox, Coyote, Hawk 1
3. If you were to take a walk through a part of Yellowstone National Park, which level of the food web would you expect to see the most of? Which level of the food web would you expect to see the least of? Explain your reasoning. You should expect to see more producers and less higher level consumers (2o and 3o consumers) As we go further along a food chain, there are fewer and fewer consumers. In other words, be a large mass of living things at the base is required to support a few at the top. Many herbivores are needed to support a few carnivores and many producers are needed to support those primary consumers. 4. What role does bacteria play in the food web? Explain. Bacteria work at all levels of the food web. They decompose waste and dead organisms to transform organic matter back into inorganic matter. This inorganic matter is then available for producers to use. 5. If a disease affecting plants were to infect this ecosystem, which of the following would have the greater impact: the decline of the aspen or the decline of the sage bush? Explain your reasoning. The decline of the aspen as it is the only food that beavers eat in this food web. A decline in the aspen would cause a decline in the number of beavers. While the sage brush is a food source for many animals, all those consumers do consume other producers. 6. Describe the role of each main trophic level in the material flow (chemical recycling) of the food web. Producers take the inorganic material from the environment and convert it to organic matter. Consumers take the organic matter and move it through the ecosystem by eating and producing waste Decomposers break down dead matter and waste which transforms the organic matter back into inorganic matter. 7. True or false? Explain your answers. a) The freezing of a lake can be considered a natural disturbance. True. This disturbance is not caused by humans. b) Excessive hunting and fishing are human disturbances of ecosystems. True. Excessive hunting and fishing can alter the dynamics of an ecosystem. 2
c) All types of natural disturbance can occur in Québec. False. Some natural disturbances, such as sandstorms or volcanic eruptions, are unlikely to occur in Québec. d) Ecological succession occurs only after a natural disturbance. False. It also occurs after a human disturbance. 8. What is ecological succession? Ecological succession is the series of changes that occur in an ecosystem after a disturbance and that continue until the balance of the ecosystem is restored. 9. Do the studies described below relate to a biotic or an abiotic factor? a) An ecologist studies the effect of hares browsing on a population of fir trees. Biotic b) Chemists test the acidity of a soil sample. Abiotic c) A water specialist assesses the amount of sunlight at different depths in a lake. d) Ecologists test a river for amounts of phosphorus from agricultural fertilizers. Abiotic Biotic 10. Why does the size of the hare population in Québec decrease when the size of the lynx population increases? The lynx preys on the hare. If the number of lynx increases, they will hunt more hares, which will reduce the size of the hare population. 11. When the same number of wheat and barley seedlings are planted in a single container, both species try to take the water and nutrients available. a) What type of interaction exists between the wheat and the barley? Explain your answer. Interspecific competition because the two species are competing for access to limited resources. b) What effect will this interaction have on the density of the two populations? It will tend to lower the density of the two populations. 3
12. Animal population A lives in the same habitat as a different animal population B. What relationship exists between these two populations according to the graph below? A) Population A preys upon population B. B) Population B preys upon population A. C) Population A and population B compete. D) Population A is a parasite on population B. C) Population A and population B compete (population A is gaining more of the resources) if it were a predator prey relationship the prey would increase first, then the predator then the prey would decrease and finally the predator would decrease. We know it s competition because as the second population continues to decrease, the other one continues increasing. Therefore, the increasing population is not linked to the decreasing one. 13. The table below lists the contents of two aquariums, A and B, both with a capacity of 50 L. Answer the following questions. Aquarium A has 6 goldfish, 5 snails, 9 elodea, 1 fern, 4 stripped fish and 2 bottom feeders. Aquarium B has 10 goldfish, 2 snails, 5 green algae, and 9 stripped fish and 1 bottom feeders. a) Compare the species richness of the two aquariums. Aquarium A has 6 different species while aquarium B has only 5 species. Aquarium A is more species rich. 4
b) Find the relative abundance of each of the species in the two aquariums. Aquarium A (total 27) Aquarium B (27 total) 6/27 x 100 = 22% goldfish 38% goldfish 5/27 x 100 = 19% snails 8% snails 9/27 x 100 = 33% elodea 4 % bottom feeders 4/27 x 100 = 15% stripped fish 19% green algae 2/27 x 100 = 8% bottom feeders 33% stripped fish c) Which aquarium has the greater biodiversity? Explain your answer. Aquarium A has a greater biodiversity because it has more species. Note: If the two aquariums have the same number of species, the aquarium with relative abundances that were more similar would be more diverse 5
d) What is the population density of snails in Aquarium A? Population Density = # individuals of species in interest area = 5snails 50L = 0.1 snails L e) What is the population density of snails in Aquarium B? Population Density = # individuals of species in interest area = 2snails 50L = 0.04 snails L 6