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# Biology I Midterm Study Guide ## Chapter 5% - Population Growth **21. What are some reasons a population may increase?** Immigration, abundant food/space/resources, less predators. **22. Define invasive species.** A non-native species that causes ecological problems. **23. What is carrying c...

# Biology I Midterm Study Guide ## Chapter 5% - Population Growth **21. What are some reasons a population may increase?** Immigration, abundant food/space/resources, less predators. **22. Define invasive species.** A non-native species that causes ecological problems. **23. What is carrying capacity?** The maximum number of individuals an environment can support. **a. When does carrying capacity occur in the graph?** Phase III. **24. Define limiting factors.** Factors that increase the growth population. **25. List examples of limiting factors.** Predation, emigration, competition, natural disaster, human activity. **26. Describe the predator-prey relationship.** If the predator population increases, the prey population decreases and vice versa. **27. What is a keystone species? Give two examples.** A species that the ecosystem depends on. Examples: sea otter and Yellowstone gray wolf. **28. Explain trophic cascade. Give an example. (BE VERY SPECIFIC!)** The dramatic change in the ecosystem because of the removal of the keystone species. For example, when the gray wolf was removed the elk population dramatically increased, the plant population decreased tremendously, and all other areas of the ecosystem were impacted because of this. ## Carbon Cycle **29. List four ways carbon dioxide is released into the atmosphere.** a. Respiration b. Decomposition c. Volcanic eruptions d. Burning of fossil fuels **30. List the main way carbon dioxide is used.** Photosynthesis **31. Too much carbon dioxide in the atmosphere causes the...** Greenhouse effect, which may cause global warming. **32. Carbon dioxide is mainly used by plants during the process of...** Photosynthesis. ## Nitrogen Cycle **33. Organisms need nitrogen to make...** Proteins **34. Most nitrogen in the atmosphere is...** Free nitrogen (gas). **35....are the ONLY organisms that can cause nitrogen gas.** Bacteria **36. Bacteria that use nitrogen are found in places such as...** Soil, water, and legumes. **37. nitrogen fixation** Is the process of bacteria converting nitrogen gas into nitrogen compounds. **38. denitrification** Is the process that turns nitrogen compounds back into nitrogen gas. a. Nitrogen compounds are nitrates, and b. Nitrogen compounds are found in... (and decomposing organisms) c. Plants use nitrogen compounds. Then, consumers. ## Phosphorus Cycle **39. Erosion and weathering of rocks and minerals add phosphate to the...** Soil **40. The phosphorus cycle is the only cycle that does not...** Pass through the atmosphere as a gas.