APES Fall Final Review Outline In order to be considered a “sustainable” practice, it must preserve the condition of the resource/environment today, tomorrow, and do it in such a way that it is healthy to the environment. 2. Human population growth began arithmetically in a linear fashion. Now, and for the past 4,000 years, the human population has grown exponentially. 3. A limiting factor in an environment is anything that “limits” the growth of an organism or a population of organisms. It can be resources, size of environment, etc. A vernal pond (small seasonal pond) can be a limiting factor in how large a fish population is allowed to get. The vernal pond actually dries up seasonally, so any fish who live there would have to be fast breeders, and able to migrate to an area where the water remains. Available food is also a limiting factor. A petri dish filled with nutrient agar has a “limited” amount of food for the growing organisms to consume. Once the bacteria or fungi have consumed the nutrient, the population will plummet because of lack of food. The carrying capacity of an ecosystem is the maximum population of a species that the environment can support. Once the carrying capacity of the petri dish is reached, the population plummets. 4. Volcanoes can influence global climate and temperatures, because of the gases which are emitted. Gases such as H20, sulfur dioxide, carbon dioxide can all alter the structure of the atmosphere. 5. In Earth’s atmosphere currently, the most prevalent gas is N 2. Oxygen is a distant 2nd. Earth’s atmosphere is very important to life on Earth as it is a protective layer of gases that prevents the sun’s most damaging rays from entering and wreaking havoc. Other gases in our atmosphere (greenhouse gases, like CO2, and H2O) work to blanket the Earth and keep her warm. Much warmer than she’d be without them! This is known as greenhouse effect. It is an important, essential process that keeps Earth’s temperatures to a “livable” range. There has been a great deal of negative publicity lately about global warming as a result of rising emissions and increased greenhouse effect. While that is all true, without the greenhouse effect, Earth would be far too cold to support life as we know it. 6. Know the nitrogen cycle: Nitrogen Fixation: Soil bacteria convert N2 (atmospheric nitrogen) into ammonia (NH3) Nitrification: Nitrifying bacteria convert the ammonia into nitrate. Assimilation: Nitrate is assimilated and absorbed by plants (which are consumed by animals to pass the nitrogen on in the food web) This nitrogen in plants is used to help make amino acids, the building blocks of proteins. Ammonification: After death, ammonifying bacteria break nitrogen compounds in the body down, and return them back to the soil in the form of ammonia. Denitrification: Denitrifying bacteria can take nitrates and convert them into atmospheric nitrogen again, completing the cycle. Nitrates are the form of nitrogen that is most usable by plants. 7. Know the hydrologic cycle: Hydrologic cycle Processes: Evaporation: liquid to a gas; Condensation: gas to a liquid (clouds); Precipitation: liquid or solid to the ground; Runoff: over the ground; Infiltration/percolation: Into the ground; Transpiration: Plants participating in the cycle as water vapor moves through the stomata of a plant. The parts of the cycle which move against gravity, are transpiration and evaporation. All other processes work with gravity. 8. Know the phosphorus cycle: This is the simplest cycle. Most of the phosphorus found in the phosphorus cycle originates in the rocks beneath your feet. (if a cycle has an origin). From the rocks, with the aid of the hydrologic cycle, it is removed and transported in the water and soil, where it is taken up by the plants, which are eaten by the animals. Phosphorus is then added back to soil when organisms die, and has the potential to be turned back into rocks again. Phosphorus does NOT have an atmospheric stage! 9. Energy flow and Food Webs/Chains: The 10% rule: Only 10% of the available energy at each trophic level is transferred to the next level. An ecological pyramid illustrates the 10% rule. So, if there is 8,596 units available at the producer level, the primary consumers incorporate only 859.6 units, secondary…85.96 etc...also know how to determine how much energy is lost to the environment. If there is originally 1,000 units (at the producer level), and by the time it gets to the secondary consumer, there are only 10 units left, 990 units were lost. The levels of ecological organization from largest include: Biosphere; ecosystem; community; population; organism 10. In aquatic ecosystems, dissolved oxygen levels are very important to the life there. Fish, tadpoles, and all aquatic animals rely on levels of dissolved oxygen to breath. The colder the temperature of the water, the more dissolved oxygen the water can hold. In the summer, when water temperatures rise, dissolved oxygen levels drop to such a point that it may stress organisms vulnerable to the lower levels. Dissolved oxygen levels are subject to change due to other considerations besides temperature 1. 11. 12. 13. 14. 15. 16. 17. 18. too, such as presence of consumers, and producers. Consumers use dissolved oxygen, so the more consumers you have in an area, the more dissolved oxygen gets used. Producers (aquatic plants) make dissolved oxygen, so the more there are, the more DO is present, however, plants also use DO during cellular respiration. The presence of decomposers also uses a great deal of DO in an aquatic ecosystem. Organisms serve several functions in ecosystems. Keystone species are vital to the community at large. The extinction of a keystone species would cause devastation to the ecosystem, perhaps to the point that it cannot recover immediately. The buffalo were a keystone species on the American Plains, vital to the grasses, Native Americans, and many other omnivores and carnivore predators. Indicator species are species which serve as early warning signs that a community is being altered or damaged over time. They are usually extremely susceptible to any kind of environmental stressor (like pollution). Many kinds of insect larva are indicator species in aquatic ecosystems. Types of relationships in nature: Symbiosis is the name given to relationships formed between DIFFERENT species. There are many types of symbiosis. Mutualism is a relationship formed where both individuals benefit. Commensalism occurs where one benefits and another is UNAFFECTED. Parasitism occurs when one benefits and another is harmed. Competition can also occur among species. Exploitative competition occurs when a competing species has roughly equal access to a specific resource but differs in how fast or efficiently they utilize it. Interference competition occurs when contending species end up not having equal access to some resources, like one species can chase another (competitor) away. Success is change in an ecosystem over time. It is like the “evolution” of the ecosystem. Left alone for a long enough time, a field of grass will become a forest. There are two types of succession that you must know: Primary succession occurs on brand new land, like volcanic rock. No soil has formed there yet. It is the job of the primary successors to make soil! Secondary succession occurs in all other circumstances. When there has been a flood, or a fire, or any kind of natural or anthropogenic disaster, as long as there is soil, secondary succession is the process that re-colonizes the area. Primary makes soil, and includes pioneer species such as mosses, lichens, and grasses. Life strategies for organisms include r – selection and K – selection. The r-selected species tend to be small, and plentiful. They reproduce rapidly, have a short lifespan. They do not spend time with, or nurture their young. Once born (or hatched), and r-strategist is on its own! r-strategists do relatively well in an ecosystem that is rapidly changing. Insects are r-strategists. K-strategists are relatively larger, have far fewer offspring, and live a much longer life. As a result, they spend time parenting and ensuring that the next generation lives. Elephants and people are K-strategists. K-strategists do better in stable environments. Endangered species are species that are in imminent danger of becoming extinct. Threatened species are those which are in imminent danger of becoming endangered. The greatest threat to most species today is habitat loss, mostly due to human consumption patterns. Threats to species include biological magnification. This occurs when a pollutant is added to the Earth, taken up by plants, consumed by animals, and moved up through the food web. It just so happens that the top consumer usually winds up with the most toxin in their bodies. The toxin is “magnified” as you move up through the chain. Know the formula for calculating population growth rates: GROWTH RATE = Current Value – Past Value/Past Value x 100. There is another way to calculate the growth rate. Instead of using actual birth numbers, and death numbers, you would use the Crude Birth Rate, and the Crude Death Rate. (CBR and CDR).These are figures that represent a population based on 1,000 individuals…such as CBR of 17, and CDR of 23. That would be 17/1,000 in a year, or 23/1,000 in a year. To calculate population growth rate using these figures, the formula is r=CBR-CDR In an environment, limiting factors are anything that “limits” the reproductive success of organisms. The tectonic plate theory states that a divergent boundary is one where new crust is being formed from an upwelling…such as the mid-Atlantic ridge. A convergent boundary is one that forms where two plates “smash”, “grind”, or “glide” together. One plate (the more dense oceanic crust made of basalt) subducts beneath the less dense continental plate (granite). There are many dangers in earthquakes for people, such as tsunamis, and liquefaction. However, the most deaths occur to people because of poorly constructed buildings either for work, or home. Volcanoes may contribute to global temperature change because of the chemicals they emit, changing the nature of the atmosphere. 19. Currently, our atmosphere is composed of: a. Nitrogen 78% b. Oxygen 21% c. Argon; Helium; CO2; H2O; Hydrogen; Krypton; Xenon (trace gases) 1% 20. The Greenhouse Effect is a natural process that impacts the climate of Earth in a positive manner. We influence this effect through our burning of fossil fuels, and CO 2 emissions, which add to our atmospheric blanket and trap solar radiation close to our surface. This can raise global temperatures, even though most of the radiation from the Sun never even reaches the Earth’s surface due to reflection off of clouds, and ozone. Any shift in atmospheric levels of CO2 could induce climate change in an ecosystem. 21. Hydrologic cycle is driven on Earth by the Sun’s energy, and includes: a. Precipitation (water in any form falling to the earth) b. Condensation (liquid water forming from gaseous water…requires a condensation nuclei) c. Evaporation (gaseous water forming from liquid water) d. Transpiration (movement of water through plants) e. Infiltration (movement of water down through the Earth to enter groundwater) f. Run off (movement of water over the surface) 22. Species that are introduced into an ecosystem are known as invasive alien species. They may wreak havoc in an ecosystem, largely because they will out-compete the other organisms as they’ll have no natural predators (or organisms that consume them naturally if they’re plants). As a result, many introduced species thrive in their new ecosystems. 23. When organisms consume toxins in their environment, the toxin becomes “magnified” in the tissues of the organisms at the top of the food chain. That is because of the biomass they consume. If each little creature the top consumer eats contains a tiny bit of the toxin, they will get the largest dose, so top predators are the most in danger from this process. This is known as biological magnification, or bioaccumulation. Example: DDT in Bald Eagles and Polar Bears. 24. When glaciers and the ice sheets melt due to global warming, scientists predict that the Earth’s temperature will rise even more. This is largely due to the fact that snow and ice cover reflects the Sun’s rays, which keep the ground and troposphere (layer of atmosphere closest to the Earth) colder. Land (whether it be rocky and barren, or green and lush) will absorb more of the sun’s energy, and heat up the troposphere. 25. The greatest single threat to species on Earth is habitat destruction. The greatest single threat to our National Parks is human activity. 26. Types of rocks on Earth, and the Rock Cycle: a. Igneous: Volcanic, forming at just beneath the Earth’s surface, crystalline structure b. Metamorphic: Beneath the Earth’s crust, changing due to pressure and heat c. Sedimentary: Form on Earth’s surface from erosion and deposition of tiny particles that over time, and due to increasing pressure due to overburden, make layered rocks. These rocks form a vast carbon sink (storage area for carbon) on Earth as well. 27. Know the carbon cycle, and how photosynthesis and cellular respiration are a part of it. Know that the carbon cycle is particularly important to the Earth, because the distribution of carbon in our atmosphere can dramatically alter the temperatures. CO2 levels fluctuate on Earth seasonally, largely due to seasonal photosynthesis of plants. 28. In the nitrogen cycle, nitrogen can be fixed atmospherically (by lightning), or biologically (by bacteria). The nitrogen fixation that occurs in bacteria largely takes atmospheric nitrogen (N 2) and converts it to NH3 (ammonia). Ammonia is rather toxic, but nitrite bacteria can take ammonia and convert it into nitrite (NO2). Nitrite is also somewhat toxic, but nitrate bacteria take the nitrite and convert it to NO3 (nitrate), which the plants are able to take up and use in their tissues to build amino acids. Animals consume the plants and get their nitrogen that way. If it weren’t for those tiny bacteria, all the nitrogen in our atmosphere would go unused, and there would be no life at all. 29. In any ecosystem, the energy available decreases at each trophic level. The higher up the food chain you go, the less the amount of energy available for consumption. Consumers participate in food chains by consuming plants and other consumers and incorporating the chemical nutrients into their bodies. Remember, the ULTIMATE SOURCE of all energy on Earth (as far as food webs/chains) go…THE SUN!!! 30. Of all consumers, parasites feed at all trophic levels. 31. In a nutshell, Natural Selection is one of the processes that drives evolution. Nature selects those individuals in a population that are the best adapted, and they survive to pass on their characteristics to the next generation. Darwin came up with this mechanism by observing many organisms on his long journey in the mid-1830s, such as finches and tortoises. Finches, he noticed, had many adaptations to the foods they were eating. Many had long narrow beaks that were perfect for drinking nectar. Others were short and powerful, to crack hard seeds. Natural selection is a process that drives evolution. Basically, certain traits are selected for by nature because the organisms that contain them, survive to reproduce. Those traits carried by the individuals that survive to reproduce are successful at moving into the next generation. That is why giraffes have long necks now. The giraffes in the original population with longer necks (due to some random mutation), were able to survive because they got more food. They reproduced, and passed on the long-neck gene. 32. Dissolved oxygen is the oxygen that aquatic organisms use. It can come from the atmosphere, and it can come from aquatic plants as a byproduct of photosynthesis. Dissolved oxygen, just as any gas, will stay in solution under certain conditions. The colder the water is, the higher the DO content, and the warmer the water is, the less DO can be held in solution. That is why many fish have difficulty in water that is too warm, because there is often times too little DO present. It stresses them. 33. The most rapid increase in the presence of CO2 in our atmosphere in recent history, coincides with the advent of the Industrial Revolution. 34. Specialists, (organisms that have very specific needs, niche wise) are more likely to become extinct than generalists (organisms that have varied needs, and can adapt easily). 35. The following are all good reasons to preserve biodiversity: Some species are keystone species in their ecosystems; Some species have economic and medicinal benefits to us; Each species is unique and irreplaceable; Each species is of scientific interest and has a role in its ecosystem. The following reason is anthropocentric, and not a good reason to preserve species: Each species must have an inherent value to us to be preserved 36. Most of the atmospheric oxygen on Earth is produced by the process of photosynthesis 37. The ecological levels of organization, from broad to specific are: Biosphere; Ecosystem; Community; Population; Organism 38. Geographic isolation is a mechanism of speciation. One species that is divided geographically may become two different species. For this reason, decreasing geographic isolation will lead to an increase in biodiversity, because the genetic materials from those distant populations can be reintroduced. 39. Plants synthesize glucose in photosynthesis; Denitrification is the process that returns N 2 (nitrogen in our atmosphere) from the soil back to the atmosphere; Transpiration leads to precipitation 40. The fundamental cause of seasons on Earth have nothing to do with the distance of the planet to the sun…which by the way, we are closer to the sun during the Northern Hemisphere’s winter season. It has, instead, to do with the tilt of the Earth’s axis, and the resulting angle of the sun’s inclination on the Earth’s surface. 41. Greenhouse effect is caused by increasing CO2 levels in our atmosphere. These can be anthropogenic, or natural…such as with the burning of fossil fuels, or the natural cycle of photosynthesis, and respiration seasonally.