Ecology Exam Study Guide

Ecology Exam Study Guide 1. Explain the differences between the following levels of ecological organization: 1. 2. 3. 4. 5. biome community ecosystem population species In terms of size the biome is the largest and contains all the others. An ecosystem is made of a few to many communities. Communities are comprised of different populations. Each population contains individuals of the same species. 2. Compare and contrast the movements of energy and matter throughout the biosphere. Both energy and matter move through an ecosystem through trophic levels being passed from one level to the next. They differ in that matter is recycled through water and nutrient cycles. Energy flows through the ecosystem and is not recycled. Most of the energy coming from a trophic level is lost as heat. Only approximately 10% of energy is passed on to the next level. 3. What is the ultimate source of energy for the biosphere and what has to happen in order for living things to use it? Most of the energy that enters the biosphere as sunlight. Photosynthesis captures 1% of the energy hitting the Earth. Herbivores (or first level consumers) will get 10% of that energy. Second level consumers will get 10% of the energy from level one and so on. Some energy enters into the biosphere through chemoautotrophs in places where sunlight doesn’t reach like caves or deep sea vents where hydrogen sulfide serves as the source of energy. After the energy is captured by the chemoautotrophs, the transfer of energy up trophic levels is the same as on the Earth’s surface. Ten percent of the energy is transferred to the next trophic level and 90% is lost as heat. 4. Explain how nitrogen cycles throughout the biosphere. Starting with nitrogen gas in the atmosphere - nitrogen is put into a form that plants can use by nitrogen-fixing bacteria. The nitrogen is part of the plant and then the animal that eats the plant. When the plant or the animal dies nitrogen is recycled into the atmosphere by denitrifying bacteria. 5. a. Explain how carbon cycles throughout the biosphere. Use the diagram to outline the carbon cycle b. In what ways do humans contribute to the carbon cycle? Use the diagram to identify the part of the carbon cycle that is from human sources c. Where does the carbon in fossil fuels come from? Decomposed organisms from millions of years ago 6. a. On average, what proportion of the energy in an ecosystem is transferred from one trophic level to the next? 10% b. Where does the rest of the energy go? 90% of the energy is lost as heat 7. Compare and contrast phytoplankton with zooplankton. Phytoplankton are photoautotrophs (producers) and zooplankton are first level consumers. Answer the following questions using the food web. 8. Which organisms are producers? Phytoplankton and seaweed 9. List 3 carnivores in this food web. Any of the animals that feed on other animals are carnivores. 10. a. This food web is missing decomposers. What would be an example of a decomposer that would be found in an aquatic ecosystem? Which organisms on land are decomposers? b. Add that decomposer to the food web. No matter where the decomposer is added to the food web all arrows will go from each organism to the decomposers. 11. On average, will the leopard seal receive more energy from the phytoplankton when it consumes the seagull or the fish? Why? The energy form the phytoplankton is four steps from the seal when it consume the seagull. The energy from the phytoplankton is three steps from the seal when it consumes the fish. More of the phytoplankton energy would be found in the fish than the seagull. 12. If the seaweed has 40,000 Calories of energy, how many calories would be available for the elephant seal? Count the number of levels and move the decimal that many places to the left. 40 calories is the answer. 13. List 3 abiotic factors and 3 biotic factors in an ecosystem. Abiotic: light, heat, water Biotic: plants, bacteria, carnivores 14. How is an organism's niche different from its habitat? The niche includes the role the organism plays in the ecosystem and how it interacts with the biotic and abiotic factors 15. What is the competitive exclusion principle and how does it shape communities? Different species will divide the resources rather than compete directly. 16. Explain the differences between the following types of symbiotic relationships: 1. 2. 3. 4. 5. commensalism competition mutualism parasitism predation Commensalism - the host is not bothered by the other organism who benefits from the relationship Competition - two or more organisms are getting energy from the same source Mutualism - both organisms benefit from the relationship Parasitism - one organism feeds on or in another and causes harm to it Predation - one animal captures and feeds on another 17. a. What is the role of a pioneer species in ecological succession? Pioneer species are the first to move into an area that has had any previous life removed. They will develop soil that helps the succession of plants to grow b. Primary succession tends to take much longer than secondary succession. Why? Soil is in place for secondary succession and climax communities must have substantial soils. Soil building takes a long time and requires the presence of pioneer species 18. How is exponential population growth different from logistic growth? Sketch of graph to illustrate each. Exponential growth has the “J” shape and logistic growth shows an “S” shaped curve. Exponential growth takes place when limiting factors are not affecting population growth. Logistic growth begins like exponential growth and then population growth slows as the population reaches the system’s carrying capacity and then levels off and continues to fluctuate around the carrying capacity. 19. List 2 density-dependent and 2 density-independent factors that help determine the carrying capacity of a population. Density-dependent: competition, predation, herbivory, parasitism and disease, stress from overcrowding Density-independent: natural disasters (weather or geologic). These are instances where the presence of living things does not play a role. 20. Describe the 2 most important density-dependent limiting factors for humans. Defend your choices. Agriculture, development, industrial growth, 21. List 2 specific ways that humans can preserve biodiversity. Protect individual species, preserve habitats and ecosystems, and approach problems with the idea that local control is important. 22. List 2 specific ways that humans are threats to biodiversity. Altered habitats, hunting and demand for wildlife products, introduced species (invasive species), and pollution. 23. What is sustainable development? Using resources in an environmentally conscious way. How can it help minimize the negative impacts of human activities? Provides for human needs while preserving the ecosystems that produce the resources. It should not cause long-term harm to the soil, water, or climate. It should be able to survive environmental stresses. It should take into account human economic systems as well as ecosystem goods and services 24. a. How has agriculture helped shape civilization? Agriculture has provided enough food for civilizations to develop in areas other than food gathering. b. What is a benefit of monoculture agricultural practices? Time is saved by planting and harvesting only one crop c. What is a downside of monoculture agricultural practices? Monoculture requires high energy costs, increased amounts of fertilizers and impacts freshwater and fertile soil. 25. How are renewable resources different from nonrenewable resources? Give examples of each. Renewable resources can be replaced or produced from a healthy ecosystem. Trees are an example of a renewable resource. One three can be cut down and be replaced by planting another. Nonrenewable resources cannot be replaced within a reasonable amount of time. Fossil fuels are an example of nonrenewable resource because fossils fuels take such a long time to produce. 26. a. How does the average ecological footprint in America compare to the world's average? The ecological footprint of an American is four times the size of the global average. b. When calculating a population's ecological footprint, what factors need to be considered? Researchers look at the consumption and waste generation of a person and then calculate what the ecological footprint of a population is. An ecological footprint is the amount of land and water systems necessary to provide the resources and to absorb the wastes generated by a population.