IB HL Biology: Ecology Review Fall 2017 Populations 1. Define the following terms associated with population ecology; population and carrying capacity. 2. What processes contribute to changes in population size? 3. What are some factors which can increase the carrying capacity of a population? Decrease? 4. What is quadrat sampling? When would it be used? Communities 5. Define the following terms; community, autotroph, heterotroph, producer, primary consumer, secondary consumer, detritivore and saprotroph. 6. What is the initial energy source for all communities? 7. Be able to read food webs and determine the trophic level of different species. 8. Choose 2 regions below and determine the Simpson’s Diversity Index value for these regions. Which region is more diverse? A. An area of the Black Forest in Germany contains 134 pitch pines, 24 douglas firs, and 53 red pines. B. A meadow contains 1532 chestnut oaks, 342 black cherry trees, 12 white ash trees, and 1022 yellow birches. C. You school science classroom contains 12 beetles, 34 termites, 84 ants, 93 fleas, and 1 butterfly. D. An African park contains 15 lions, 94 giraffes, 1000 wildebeests, 50 elephants, and 5 hyenas. Choose more areas if you need more practice. 9. What is a keystone species? 10. Distinguish between primary and secondary succession. Ecosystems 11. What is an ecosystem? 12. Explain the 10% rule of energy transfer. How is the energy lost between trophic levels? 13. Review the Carbon Cycle. What are the main sources of carbon dioxide on earth? 14. Review the Nitrogen Cycle. 15. Distinguish between Gross Primary Productivity and Net Primary Productivity. 16. What is the Greenhouse effect? 17. How have human activities influenced climate change? When did human activities begin to influence climate change? Why? 18. What are the most common greenhouse gases? Human Impact on the Environment 19. What are invasive species? Why are they able to take hold in a new habitat? 20. Describe biomagnification. Name one toxin / substance that experiences biomagnification in the environment. 21. Distinguish between In-situ and ex-situ conservation methods. 22. What impact do plastics have on ocean ecosystems? PRACTICE PROBLEMS 1.. A researcher is trying to estimate the population abundance of Lodge Pole Pine Trees in Rocky Mountain National Park. He divides the park into quadrats and counts the number of trees in a number of randomly selected quadrats. Below is a representation of his data. Rocky Mountain National Park 5 9 2 8 11 2 5 8 8 9 3 7 2 2 4 6 1 5 7 What is the population estimate for Lodge Pole Pines in Rocky Mountain National Park? Average number of trees in the sampled quadrats = 5.47 number of quadrats = 180 N = 180(5.47) N = 984.6 985 Lodge Pole Pines What would you need to know and do to determine the density of trees in the park? You would need to know the area of the park Density = number plants / area (be sure to include correct units) 2. Another researcher is trying to estimate the number of Fox Squirrels living in Lakewood. She uses the mark – recapture method to estimate the population size. The following data was collected. Number of squirrels initially caught and released = 42 Total number of squirrels caught in second sample = 23 Number of marked squirrels in the second sample = 4 What is the population estimate? N = (42)(23) / 4 N = 241 3. During a several-year period of drought, the population abundance of mice, voles, rats and chipmunks in an oak forest remains at a relatively constant, low level. Then a period of heavy rainfall ends the drought and results in a large increase in the population of acorns – a favorite food of rodents. The rodent population during this year would be expected to a. decline because of excess rainfall. b. decline due to the competition from other species. c. remain almost constant, with little or no variation. d. increase in direct proportion to the increase in acorns. e. increase much more rapidly than the increase in acorns. 4. A mouse population lives in a semi-desert environment that has been affected by global warming. In the past twenty years, temperatures in the area have increased by an average of three degrees Fahrenheit, and rainfall has decreased by about five inches per year. Over this time period, it is likely that the mice in this population have a. grown larger and produced more offspring. b. lived longer and produced more offspring. c. gotten smaller and produced fewer offspring. d. had shorter life spans and produced more offspring. e. not changed; they are well adapted to any changes in the environment. 5. Sparrows eat both insects and seeds. To which trophic level do they belong? a. primary consumer b. secondary consumer c. tertiary consumer d. omnivore 6. Food webs describe the ______ within a community. a. uptake of solar energy b. distribution of organisms c. flow of nutrients and energy d. competition among organisms 7. Decomposers obtain energy from which trophic level or levels of a food web? a. All levels b. Omnivores only c. All producers only d. All consumers only e. Secondary and tertiary consumers only 8. A rough measure of the flow of both energy and materials through ecosystems can be obtained by measuring a. gross primary productivity b. net primary productivity c. output of biogeochemical cycles d. geographic distributions of plants e. flow through the hydrologic cycle 9. Complete the diagram of the nitrogen cycle by naming the organisms involved in processes A, B and C below. denitrification N 2 in atmosphere Denitrifying C. bacteria (Pseudomonas lightning denitrificans) Proteins in feeding Proteins in plants animals death excretion absorption Fertilizers A. Nitrates in soil decomposition Ammonium salts in soil B. Nitrifying Nitrites in soil bacteria (Nitrosomonas) (3) A = decomposers / saprophytes B = nitrifying bacteria C = nitrogen fixing bacteria 10. The graph below shows the variation in the concentration of atmospheric carbon dioxide since 1970. 375 370 365 360 355 CO 2 350 concentration / ppm 345 340 335 330 325 320 0 5 0 5 0 5 0 7 7 8 8 9 9 0 9 9 9 9 9 9 0 1 1 1 1 1 1 2 [Source: C D Keeling and T P Whorf, Atmosphere CO2 concentrations (ppm) derived from in situ air samples, collected at Mauna Loa Observatory, Hawaii] The annual fluctuation is mainly the result of changes in the levels of photosynthesis associated with the seasons in Northern Hemisphere forests. (a) (i) Describe the overall trend shown in the graph. (1) (ii) Suggest a cause for the overall trend throughout the period 1970–1999. (1) (b) (i) Using a clear label, identify any one point on the graph which shows the CO2 level in mid-summer. (ii) Explain why the concentration of CO2 varies with the seasons. (2) Think about trees that lose their leaves (c) Identify one gas, other than CO2 , which is contributing to the enhanced greenhouse effect. (1) Methane , water vapor 11. Understanding the ecological mechanism that causes extinction is fundamental to conservation as not all organisms are threatened by the same factors. A total of 1012 threatened bird species in 95 families were studied to see how they were threatened by different factors: habitat loss persecution by humans and introduced predators other factors (introduced competitors, hybridization and disease) and unknown risk factors. Scientists investigated the relationship between body size and the risk of extinction, both due to habitat loss and to persecution/predation. Birds were classified as small (mean body mass 1 to 1000 g) and large (mass greater than 1000 g). The results are shown in the pie chart and bar charts below. Percentage of all 1012 species Extinction risk from habitat loss threatened by each type of factor 6 20% 5 Percentage of 4 species in 3 family at risk 2 45% 1 10% 0 Small Large Body size Extinction risk from persecution/predation 25% 6 5 Habitat loss only Percentage of 4 species in Habitat loss and predation / persecution 3 family at risk Predation / persecution only 2 1 Other / unknown 0 Small Large Body size [Source: Modified from B Owens et al., Proceedings of the National Academy of Sciences, (2000), 97, pages 12144–12148. Copyright 2000 National Academy of Science, USA] (a) (i) State the percentage of species affected in some way by habitat loss. (1) 70% (ii) Calculate the approximate number of bird species threatened by predation / persecution only. (1) 101 +/- 1 (b) State two factors that could have caused habitat loss. (2) Fire, climate change, logging, pollution, drought (c) Outline, using the bar charts, the effect of body size on the risk of extinction. (2) (2) Small = habitat loss Large = persecution / predation (d) Discuss the methods of conservation that would avoid the extinction of large species. (3) In situ examples or ex situ examples (size of the animal really doesn’t matter) 5 –2 –1 2 12. The total solar energy received by a grassland is 5 × l0 kJ m y . The net production of the grassland is 5 × 10 –2 –1 2 –2 –1 – kJ m y and its gross production is 6 × l0 kJ m y . The total energy passed on to primary consumers is 60 kJ m 2 –1 y . Only 10% of this energy is passed on to the secondary consumers. (a) Calculate the energy lost by plant respiration. (2) Plant respiration = gross – net 6 – 5 = 1 x 102 kJm-2 y-1 (b) Construct a pyramid of energy for this grassland. (3) 13. The energy flow diagram below for a temperate ecosystem has been divided into two parts. One part shows –2 –1 autotrophic use of energy and the other shows the heterotrophic use of energy.