Chapter 8 Critical Thinking
#4
What would you do if large numbers of cockroaches invaded your home? See whether you can come up with an ecological rather than chemical (pesticide) approach to this probem.
First of all, one must determine whether the influx of cockroaches is actually a problem. It might be assumed that the cockroach population is that of a disturbance, a parasite perhaps. That the cockroach is merely mooching off of the food, heat, and protection that the humans provide.
There may in fact be the possibility that the humans and cockroaches can live in symbiotic ways.
The mutualism between humans and cockroaches could be beneficial: the humans provide the home and the cockroaches prevent dust mites and molds. However, if I for some reason become disturbed by the cockroach population, I could bring in a predator of the cockroach, such as a cat.
This would decrease the population of cockroaches without the use of pesticides.
#5
To determine whether a particular species was a keystone species is to determine their role in the community and ecosystem. Keystone species are known for playing critical ecological roles. See if the species is a pollinator, such as critical bees, hummingbirds, bats, and others that do the same. Another way is to see if the species is a top predator. These are carnivorous, usually being wolves, leopard, lion, alligator, and great white shark. These regulate ‘inferior’ species, controlling the flux of numbers in a population. Also, if the species helps rapidly decompose waste, like the dung beetle.
Jennifer Sawtelle
Chapter 8 Response Questions – Cadence Cadence, this is the wrong question! You were to answer crit. thinking #6, not Proj. #6
#6. George Perkins Marsh - Born in Woodstock, VT but spent most of his time in Burlington.
He was a diplomat to the Ottoman Empire, Greece and Italy, and is considered one of America's first environmentalists. He was a renowned author as well, who spoke many languages, the most famous of which was Icelandic. He also played a role in the creation of Adirondak Park.
Lawrence B. Slobodkin - Born in the Bronx, and lived in NY. Updated the definition of ecology and made it a practicable science with ties to evolution and the other sciences. He went to several different colleges, finally finishing off at Yale. He and his students sought to create broad principles for the science of ecology based on framework foundations laid by scientists like
Volterra and Gause. He was a college professor for most of his life.
#9 Jen Sawtelle

Hooray! I’m finally in charge of the world!
The first thing I’m going to do to save aquatic biodiversity is stop all coastal developments, and repair any that were damaged, or in the works of being developed, especially mangroves in the Gulf of Mexico that help protect from hurricanes, erosion, and support strong biodiversity. This would also help the marshes from being “sponged out” from houses, and protect estuaries. This in turn keeps a healthy flow of silt, and filtration of toxins from concentrating any one specific spot.
Secondly, I would mandate the amount of toxins allowed to leave any kind of processing plant to extremely low levels. This will drastically cut greenhouse gasses from accumulating. I would also regulate how many products are produced to prevent any excess waste, which would need to be put in landfills, which have toxic runoff.
That leads to my third change. I would stop offshore (or even inland) drilling for oil. A few spots would be used until an alternative was found for vehicles, but not enough to have a major impact on the greenhouse effect or the areas surrounding the drilling. This would prevent oil spills from demolishing sea life, and from wasting materials, resulting in better energy alternatives.
Jen Sawtelle
3. I agree with restoring the number of bison in North America, but I do not agree with starting off with a large number. Populations can and have gotten easily out of hand, so reintroducing a population should start at lower numbers, so other species don’t have a ‘culture’ shock. It may be hard, because other animals have filled in the niches that bison used to fill, so there may be competition.
Also, say that the bison thrive, then the biologists will have to start killing bison off again because the number of short grass prairie will be in danger, and it starts a harsh cycle of killing off species. The reason ranchers don’t like it is because, like with the niches, their cattle and sheep will have to start competing with bison for food, water, and shelter sources.
4. The reason most animals live in trees in the rainforest is because that is where the food sources are. The canopy drastically blocks sunlight, therefore the fruits that can grow must grow higher in the trees near the source of energy. Also, another reason is because of the predators.
Fire ants, jaguars, poisonous spiders and frogs, monkeys and orangutans, all of these animals could easily kill an intruder. That is also why you cannot camp on the ground, because the bugs will eat you alive.
Cadence F
Chapter 6 Critical Reading Q's
3. Some biologists have suggested that restoring large herds of bison on public lands in the
North American plains as a way of restoring remaining tracts of tall-grass prairie. Ranchers with permits to graze cattle and sheep on federally managed lands have strongly opposed this

idea. Do you agree or disagree with the idea of restoring large numbers of bison to the plains of
North America? Explain.
Although the Bison population in the midwest plains has fallen dangerously low in recent years, the speedy re-addition of the Bison will dangerously destroy the way that the permit system works for the ranchers who are allowed to graze their sheep and cattle there. The bison will also not aid in the re-growth of the tall-grass. In fact, they might even inhibit the growth of plant life, depending on how many Bison are reintroduced. Introduction of the Bison back into the grassland should be done in a much slower way.
4. Why do most animals in a tropical rain forest live in its trees?
Most animals in the tropical rain forest live in the trees because the soil near the ground is wet, inhibiting food growth (plantlife that is eaten by many of the herbivores in the rainforest) low to the ground. Many of the food sources in the rainforest actually grow off the ground as well. The ground also tends to be ridiculously moist, often causing erosion and unstable ground. It is simply safer for a good portion of the animals to live in the trees, which are much more stable and closer to the open air than the ground is.
Evon Li
Chapter 6
Critical Thinking Q's 5 & 6
5. What biomes are best suited for raising crops and grazing livestock?
Grasslands, specifically temperature, have deep and fertile soil which allows the biome to be widely used for growing crops and grazing cattle. Organic matter accumulates and produces a deep, fertile soil, because the aboveground parts of most of the grasses die and decompose each year. Due to the fact that temperate grasslands are great places for crops and animal grazing, many of the world’s natural temperate grasslands have disappeared. They are often flat, easy to plow, and have fertile, deep soils.
6. Congratulations! You are in charge of the world. What are the three most important features of your plan to help sustain the earth’s terrestrial biodiversity?
In order to help sustain the earth’s terrestrial biodiversity, first I would create a variety of reservations that protect a mixture of biomes. Through such protection, biomes will be able to flourish without human disturbances. Second, I would form laws and regulations limiting deforestation and the hunting of animals. In biomes, such as the rainforest, deforestation and extinction of animalsare becoming a large problem. Lastly, to promote the protection of such

ecosystems, people must be aware of the devastation of biomes and the impact humans have on them.
Evon Li
Chapter 7
Critical Thinking Q 5
5. Someone tries to sell you several brightly colored pieces of dry coral. Explain in biological terms why this transaction is probably fraudulent.
It isn't necessarily fraudulent. Most dry corals are just calcium carbonate, and are therefore white. However, some coral species do add pigment to the calcium carbonate matrix, most notably the bright red corals that are used in making coral jewelry. White corals are often dyed however, for sale in tourist shops.
Meghan Lynch Ch. 7 Critical Thinking #6
Developers want to drain a large area of inland wetlands in your community and build a large housing development. List (a) the main arguments the developers would use to support this project and (b) the main arguments ecologists would use in opposing this project. If you were an elected city official, would you vote for or against this project> Can you come up with a compromise plan? a. Inland wetlands provide a variety of important and free ecological and economic services such as filtering toxic wastes and pollutants, absorbing and storing excess water from storms, and providing habitats for a variety of species. If this project goes underway, then populations of species will be depleted, flooding may occur, and pollutants will accumulate in the environment. b. The housing development will provide jobs construction workers, many of whom are laid off during this economy. Additionally, the draining of the wetland will overall allow for further development of the rest of the area.
If I was an elected city official I would vote against this project because wetland ecosystems are some of the most valuable and important environments. It would cause more harm than good to carry out this project. A compromise plan might involve preserving half the land and allowing the audubon take care of it while the other half would be allotted to the housing development company.
Evon Li Ch. 7 Review Question #3

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Temperature: Because of the great amount of sunlight at the surface, the upper layer of the ocean is the warmest and the water because increasing cold as you travel further down the ocean layers.
 Sunlight: The open ocean consists of a brightly lit surface layer (euphotic zone), a dimly lit middle layer (bathyal zone), and a dark bottom zone (abyssal zone).
DO: Do Levels are higher near the surface because oxygen-producing photosynthesis
 takes place there. Photosynthesis cannot take place below the sunlit layer.
Nutrient Availability: In the shallow waters of oceans, ample supplies of nutrients for primary producers are usually available. Nitrates, phosphates, iron, and other nutrients often are in short supply and limit net primary productivity (NPP). However, NPP is much higher in parts of the open ocean where upwellings bring such nutrients from the
 ocean bottom to the surface for use by producers.
Euphotic Zone: The lighted upper zone where floating drifting phytoplankton carry out photosynthesis. Nutrient levels are low (except for upwellings), and levels of DO are high. Large, fast-swimming predatory fish such as swordfish, sharks, and bluefin tuna populate the zone.
 Photosynthesis: Photosynthesis occurs mostly on the upper layer, or euphotic zone, where
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 sunlight can penetrate. The depth of the euphotic zone in oceans and deep lakes can be reduced by excessive algal growth clouding the water.
CO2 Levels: Levels of dissolved CO2 are low in surgace layers because produces use
CO2 during photosynthesis and are high in deeper, dark layers where aquatic animals and decomposers produce CO2 through aerobic respiration.
Shallow Waters: In shallow waters in streams, ponds, and oceans, there are abundant supplies of nutrients for primary producers. There’s ample amount of DO and sunlight.