Name: REVIEW 7: ECOLOGY Ecology: POPULATIONS: Individuals of the same living in the same area. a. Dispersion: Organisms are sometimes found in groups and others times as lone individuals. The pattern of dispersion aids in survival and often relates to social behavior (clumped), territoriality (uniform), or availability of resources. clumped uniform random Three patterns of population distribution!! 1.!! 2.!! 3. wolves hawks dandelions b. Population Growth: Exponential Model: Assumes resources are. J shaped growth curve Logistic Model: Assumes resources are limited. S shaped growth curve Population growth slows due to competition and the population levels off at the. c. Population Resources: Density factors: When a population becomes larger, there is more competition for resources such as food, water, and space. Additionally, disease is more likely to spread through larger populations The larger the population size, the more density dependent factors effect the population. Density factors: Factors such as climate change and natural disasters effect populations regardless of size. Limiting resource: d. Human population growth: The population has increased due to improvements in sanitation, medicine, and technology. The human carrying capacity is estimated to be between 10-15 billion. Will be limited due to competition for nonrenewable resources. 1
e. Predator-Prey population cycles: Predators help to keep the prey species at suitable levels. Predation acts as a feedback mechanism and operates in a cycling of predator and prey populations keeping size under carrying capacities. Hare Lynx COMMUNITIES: Individuals of different species living in the same area.! a. Community interactions: competition (-/-): two species compete for same resources!!! example: Two organisms can not have the same niche (role in the ecosystem) without competitive exclusion.!! predation (+/-): one organism consumes another!!! example: mutualism (+/+): both organisms benefits from the relationship!!! example: parasitism (+/-): one organism feeds off of another organism (host is not killed)!!! example: commensalism (+/0): one organism benefits, the other is neither helped nor harmed!!! example: b. Succession: Predictable change in an ecosystem following a disturbance. primary succession: generation of an ecosystem where there has previously been no soil. example: secondary succession: replacement of an ecosystem where there has been soil previously. example: 2
with sea otters! without sea otters! c. Impact Species: Keystone species: species who s removal results in decreased biodiversity and instability in an ecosystem.!! example: Invasive species: non-native species which do not have natural predators and can outcompete native species, who s presence results in decreased biodiversity in an ecosystem.!! example: ECOSYSTEMS : Both the biotic (living) and abiotic (non-living) components of the environment a. Trophic relationships: The source of energy for all living things is light energy from the. This energy is converted to chemical energy in autotrophs by the process of. This chemical energy (glucose) can then be used in cellular respiration to make. Trophic efficiency: only approximately % of energy is passed on to the next trophic level in a food chain. This is due to the fact that at each level Energy is used in cellular respiration to fuel cell processes Energy is used for growth Energy is released unused in waste Food chains are usually no longer than 4 or 5 organisms in length. Decomposers (bacteria and fungus) return essential elements to the soil so that they can again be incorporated into autotrophs.! 3
b. Biogeochemical Cycles: recycle the elements needed by living organisms Carbon cycle: Takes out the atmosphere and converts it into sugar in the process of. Carbon containing glucose molecules are then broken down in the process and and is released and returned to the atmosphere. of fossil fuels also puts carbon dioxide into the atmosphere. Decomposition also cycles carbon back into the soil and through food chains.! Carbon is found in ALL organic compounds: carbohydrates, lipids, proteins and nucleic acids. Water cycle Water enters the atmosphere through the processes of and (loss of water from plants). Water vapor as it cools. This condensed water then falls to Earth as. Water is essential for life. Living organisms are over 60% water. Reactions in living things require water dehydration synthesis - building of polymers hydrolysis - digestion of polymers Water covers approximately 70% of the planet. Water is a reactant of photosynthesis providing electrons for the light reactions. Nitrogen cycle Nitrogen exists as a gas in the atmosphere. This gas is not directly usable by living things. Bacteria in the soil perform nitrogen fixation, converting nitrogen gas into compounds usable by plants. Nitrogen is necessary for life: It is found in the organic molecules and. 4
Phosphorous cycle Phosphorous does not exist as a gas. The source of phosphorous for living organisms is erosion of phosphorous containing rock. Phosphorous is necessary for life as it is found in (as well as phospholipids and ATP).! c. Biomes:! Terrestrial Biomes: Very large ecosystems determined by their climate amount of light temperature rainfall where there is a lot of sun, water and warmth, there is a lot of plants, and therefore animals. Biodiversity is greatest in the tropical TAIGA rain forests and decreases as you move toward the polar biomes. Aquatic Biomes: are determined by amount of light salinity movement (flowing/still)!!! WAYS HUMANS ADVERSELY INFLUENCE ECOSYSTEMS atmospheric changes: These include the the depletion of the UV protecting ozone layer and global warming due to the addition of greenhouse gases (mostly due to burning of fossil fuels). biological magnification: the accumulation of toxins as they are passed up a food chain eutrophication: Agricultural runoff leads to overpopulation of algae in lakes and ponds preventing light penetration. Eventually, the algae deplete the dissolved oxygen from the lake. habitat destruction: Loss of habitat is the #1 reason for a decrease in biodiversity (ex. deforestation of tropical rainforest) overconsumption: Using resources faster than they can be replenished (ex. over-fishing) pollution: Land, air, and water pollution have all had many adverse influences on ecosystems. population growth: Increasing numbers are using excessive amounts of non-renewable resources 5
SAMPLE EXAM QUESTIONS 1. Which term refers to the the ecological niche of many bacteria and fungi in an ecosystem?! a. decomposer!!!!! c. producer! b. herbivore!!!!! d. scavenger 2. In which row in the chart below is human action correctly paired with its environmental impact? 3. Over a long period of time, the stages represented in the diagram below were each present in a particular ecosystem.! After a forest fire, what is the most likely order in which these stages appeared? a. D C A B c. A B C D b. B D C A d. B C D A 6
4. The diagram below represents interactions between organisms in a stable ecosystem. Which statement correctly describes the organisms in this ecosystem? a. Organisms in level B obtain their energy directly from the sun. b. Organisms in level C obtain their nutrients directly from organisms in level D. c. Organisms in level A are herbivores. d. Organisms in level D are heterotrophic. Officials OK Insect Release to Control Invasive Vine! The U.S. federal government has approved the release of a non-indigenous [non-native] insect on Guam and in the Northern Marianas to control the rapid spread of a vine that is covering forests like a blanket, the Saipan Tribune reports. The U.S. Department of Agriculture has given the green light to breed and release the Heteropsylla spinulosa insect, which eats the Mimosa dilotricha vine. The fast spreading vine is found in many Pacific Islands, but is particularly widespread in the Northern Marianas and on Guam. The vine usually kills the trees and shrubs that it covers. Officials will collect the insect from Pohnpei, in the Federated States of Micronesia, Palau and Australia. 5. Discuss the advantages of using the insect to control the rapid spread of the Mimosa dilotricha vine. In your answer be sure to: a. State ONE possible way the Mimosa dilotricha vine kills trees and shrubs b. Identify ONE location from which the Heteropsylla spinulosa insect will be collected. c. Explain why releasing the insect might be safer than spraying chemicals to kill the vine. 7
Base your answers to questions 6-8 on the diagram below and your knowledge of biology. The diagram represents an energy pyramid for an ecosystem in the Australian Outback. 6. Wombats are classified as herbivores because they can a. get energy from the sun!!! c. get nutrition from the grass and sedges b. provide energy for the kookaburras!! d. provide nutrition for kangaroos 7. Which two organisms could have a predator-prey relationship? a. kookaburras and gum trees!!! c. dingos and kangaroo grasses b. kangaroos and silky mice!!! d. wedge-tailed eagles and wombats 8. Dingos are an introduced species in Australia that are outcompeting many native species. Which of the current environmental problems most likely resulted directly from the introduction of dingos to Australia? a. vanishing of kangaroo grasses!! c. forests overrun with koalas b. near extinction of wallabies!!! d. increase in the kookaburra population 9. Which question best describes prey populations in a stable ecosystem? a. They are held in check by predator interactions. b. They are producers that rely indirectly on other producers. c. They are not limited by natural predators. d. They are not dependent on other species. 8
10. Which characteristic of a geographic region would have the greatest impact on the type of ecosystem that forms in that region? a. ratio of autotrophs to heterotrophs b. concentration of atmospheric oxygen c. number of food chains d. climatic conditions Base your answers to questions 11-12 on the graph below and on your knowledge of biology. The graph contains information about an ecosystem. The graph below show the carrying capacity of an ecosystem for three different species, 1, 2, and 3, that inhabit an area and the actual population sizes of these three different species in the area. 11. Identify which species population would most likely have the greatest competition among its members. Support your answer using information from the graph. Species number Reasoning: 12. Explain how an ecosystem can have three different carrying capacities. 9
Base your answers to questions 13-17 on the information below.! An experiment was set up using three tanks to investigate the effect of a new chemical (chemical X) on aquatic life. Each tank had a different concentration of chemical X: 1%, 2%, and 3%. Ten sea urchin eggs were placed into each of the three tanks. A fourth tank was set up as a control. 13. State ONE way the contents of the control tank would differ from the contents of the three experimental tanks. 14. Identify TWO factors that must be kept the same in all four tanks.! Factor 1:! Factor 2: 15. Identify the independent variable in the experiment. 16. State ONE example of the type of data that should be collected during the experiment. 17. Make a prediction about the effect of the concentration of chemical X on the hatching of sea urchin eggs. 10