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
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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.