Chapter 4 wiki questions
Chapter 4 wiki questions:
1. An organism is any living thing. A species is a group of organisms. A population is the number of organisms
in an area. A community is the different species in an area. An ecosystem contains different populations. An
ecosphere is a group of different ecosystems. Biodiversity is variation, species variation and ecosystem
variation.
2. The biotic component of an ecosystem is that ecosystems all have living parts that play a role in how the
nutrients move around the system. Producers, consumers, and decomposers are examples of biotic
components. Producers are organisms that make their own food by photosynthesis or chemosynthesis.
Consumers are organisms that get nutrients from eating other organisms they can be herbivores, carnivores, or
omnivores. Scavengers are organisms that eat other other dead organisms. Detritus feeders break down
organic matter to get nutrients. Decomposers like bacteria and fungi are specialized consumers that recycle
organic matter. Photosynthesis uses sunlight to produce energy. Chemosynthesis produces erergy without
sunlight by converting simple compounds into more complex ones. Anaerobic respiration breaks down glucose
and doesn't use oxygen to produce energy. Aerobic respiration uses oxygen to convert organic nutrients back
into Co2 and water.
3) The Law of Tolerance is the existence, abundance, and distribution of a species in an ecosystem that are
determined by whether the levels of one or more physical or chemical factors fall within the range tolerated by
that species. The limiting factor principle is: too much or too little of any abiotic factor can limit or prevent
growth of a population, even if all other factors are at or near the optimum range of tolerance. An example of
how time and adjustments to limits are interconnected would be when a farmer plants corn in a field for a
certain amount of seasons so as to deplete the phosphorus from th soil, even if all other nutrient levels remain
the same, the corn will grow less and less with each progressive year until it stops growing once all the
phosphorus is gone and other plants, which do not require as much phosphorus as corn or perhaps no
phosphorus at all, will then take over the field and therefore the phosphorus will replenish itself and the corn
may grow back again. A threshold is the point at which there is an abrupt change in an ecosystem’s quality,
property, or phenomena, or where small changes in an environmental component produces large responses in
an ecosystem, On land, precipitation is the most common limiting factor: lack of water keeps plants from
growing which affects the food chain and too much water can “drown” the plants. Soil nutrients can also act as
a limiting factor as the above example describes. Important limiting factors in aquatic ecosystems are things
such as sunlight for warmth and photosynthesis, nutrient availability based on water temperature and location,
salinity which is just inorganic minerals and salts in the water, and also the available DO content of the water.
6) Carbon Cycle - Aerobic respiration in the cells of oxygen-using organisms converts the carbon into CO2
which is then released into the tropospere. Then the carbon dioxide is removed from the troposphere by
terrestrial and aquatic organisms through photosynthesis. Some carbon is trapped in the earth in the remains of
dead organisms. The ocean also dissolves some of the atmoshpere’s carbon dioxide which is absorbed and
released depending on temperature. Man has affected this cycle by extracting carbon from the earth in the form
of fossil fuels.
Nitrogen Cycle - Atmospheric electrical discharge (lightening) causes a reaction to occur which produces NO.
Also certain types of bacteria in aquatic systems, the soil, and roots of plants convert N2 into compounds that
can be absorbed by other organisms in the form of nutrients. Nitrogen fixation happens when specialized
bacteria in soil convert N2 to ammonia for plant use. The leftover ammonia undergoes nitrification by aerobic
bacteria which convert it to nitrite ions (toxic to plants) and nitrate ions (useful to plants). Plant roots absorb the
dissolved substances through assimilation. Animals get their nitrogen from plants and return the nitrogen to the
environment through waste products and death. Humans add large, excess, amounts of NO to the atmosphere
throught the burning of fuels which causes acid deposition. We release nitrogen from soils and plants as gas
into the troposphere through deforestation and disturb aquatic ecosystems by adding excess nitrogen through
runoff from agriculture and sewage.
The law of conservation of matter applies to biogeochemical cycles because the earth’s chemical cycles
connect past, present, and future forms of life due to the continuous recycling of the earth’s nutrients. In these
cycles, nutrient atoms and molecules that organisms need to survive and reproduce are cycled between the air,
water, soil, abiotic, and biotic aspects of the environment. All biogeochemical cycles are powered by the sun
and gravity.
Chapter 4 wiki questions
7. Ecologists use biodiversity to study the ecosystems because it studies variation, species variation, and
ecosystem variation so it allows them to see variations in different ecosystems to see how they work.
8. The Phosphorus cycle moves slowly through the water, soil, and living organisms. Very little cycles through
the atmosphere because soil conditions do not allow bacteria to convert chemical forms of phosphorus to
gaseous forms. it is often found in salts, terrestrial rocks, and ocean bottom sediments. Decomposers break it
down and leave it in the sediments. Geological uplift under the ocean can expose seafloor deposits. The Sulfur
cycle also cycles through the Earth, air water, soil, and living organisms. Much of the Earth's sulfur is stored
underground in rocks and minerals. It can enter the atmosphere through swamps, volcanoes etc. The
hydrological cycle recycles the earth's fixed supply of water. Solar energy evaporates the water into the
atmosphere, then it comes down as precipitation. It remains chemically unchanged between the stages of the
cycle. The laws of conservation of matter apply because since no matter and that includes water, phosphorus,
and sulfur, can be destroyed or created the chemicals are always on Earth in some form. We are affecting the
Phosphorus cycle by removing it from Earth to make fertilizer. This adds it to aquatic systems and reduces the
amount of phosphorus in tropical soils. We affect the sulfur cycle by adding sulfur dioxide to the atmosphere by
burning coal and oil and producing metals from ores to make zinc, copper, and lead. We impact the water cycle
by withdrawing large amount of fresh water, clearing vegetation, eroding soils, polluting surface water. Doing
these things impacts the rate of global warming especially impacting the sulfur and water cycles. Our impact on
the Phorphorus cycle leads to more pollution in the environment.
9. Primary productivity is the amount of biomass produced through photosynthesis per unit of area and time,
conducted by primary producers, such as plants. This hypothesis (also known as the "bottom-up" hypothesis) is
the idea that populations of communities are regulated by the primary trophic levels (the "bottom" of a food
chain/web), because the primary producers feed and fuel organisms of the higher trophic levels. If the
population at the "bottom" were to undergo a major change, the other trophic levels would be affected, thus the
food web is being affected by the "bottom-up". There is also the Trophic Cascade or "top-down" hypothesis.
This hypothesis is similar to the "bottom-up" hypothesis in the sense that it states that certain levels are
affecting the rest of a food web. This time, however, the change is initiated from the higher levels (the "top") of
the food web. If there is a dramatic change in the population of organisms at the higher trophic levels, the levels
below would directly be affected. For example, if there was a carnivorous species at the top of the food web,
and they suddenly had a sharp decrease in population, the organisms on the lower trophic levels who are prey
for the carnivore, would have an increase in population due to not having predators to regulate it. With an
increase of this prey (say they were omnivores), then the population of the organisms they eat will decrease
since there is more of a demand for the food with the increased number of individuals. This pattern continues
throughout the food web/chain.