AP Biology Ecology Review 2011-12
1. Describe a symbiotic relationship between bacteria and plants. (Interdependence)
Symbiotic nitrogen fixation occurs in plants that harbor nitrogen-fixing bacteria within their tissues.
Rhizobia are soil bacteria that fix nitrogen after becoming established inside root nodules of legumes
(plants or fruit of plants). Within the nodules, rhizobia are found as bacteroids, which perform the
nitrogen fixation--to do this, they obtain sources of carbon and energy from the plant. In return,
bacteroids provide the plant with ammonium and act like plant organelles to cycle amino acids back to
the plant. The biological reduction of atmospheric nitrogen to ammonium (nitrogen fixation) provides
about 65% of the biosphere's available nitrogen. Fixed nitrogen is also necessary to biosynthesize the
basic building blocks of life (such as nucleotides and amino acids).
2. Explain primary productivity. (Energy Transfer)
Primary productivity is a term used to describe the rate at which plants and other photosynthetic
organisms produce organic compounds in an ecosystem. There are two aspects of primary
productivity:
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Gross productivity = the entire photosynthetic production of organic compounds in an ecosystem.
Net productivity = the organic materials that remain after photosynthetic organisms in the ecosystem
have used some of these compounds for their cellular energy needs (cellular respiration).
Measurement of dissolved oxygen is often a method used to gauge primary productivity in an aquatic
ecosystem.
3. Describe an example of mutualism.
--Mutualism is a form of symbiosis, in which the two interacting organisms both benefit.
--Example: pollinators and nectar-producing plants
-The pollinators (ex: bees) gain food and nutrients from the relationship, while the
producing plant gets help with reproduction
nectar-
4. Energy Transfer: Diagram and describe a marine food chain.
Killer Whale
Large Carnivorous Fish
Small Carnivorous Fish
Zooplankton
Phytoplankton
Phytoplankton, a primary producer, is consumed by zooplankton, a primary consumer, which
in turn is consumed by a small carnivorous fish. This small fish is a secondary consumer and is
consumed by a large carnivorous fish, a tertiary consumer. This fish is then eaten by a killer
whale, a quaternary consumer.
5. Energy Transfer: Explain how dissolved oxygen relates to primary productivity.
Primary productivity is the amount of energy converted to chemical energy by autotrophs
during a given time period. High dissolved oxygen levels suggest photosynthesis is taking
place very frequently, which suggests a high primary productivity. Low levels of dissolved
oxygen suggest low levels of photosynthesis and low primary productivity.
6. Competition
Competition is an interaction between species. In it, two or more species strive for the same
resource, lowering the relative fitness of all species. The desired resource must be in limited
supply. Thus, the interspecific competition is for survival. The most common and apparent
resource is food. Many species compete when they live in similar habitats and have similar
prey. This type of competition is fierce because the survival of species depend on their ability
to win. A good example of such competition is between wolves and coyotes. Both species live
in similar areas and have similar diets. When prey is running low, the species able to hunt
better survives while the other dies off. Other resources that provide sources for competition
include mates, light, and water.
7. Explain net primary productivity.
Net primary productivity is the change in dissolved oxygen concentration of a sample of
water over time. To find net primary productivity, one must subtract the final dissolved oxygen
concentration of the sample form the original dissolved oxygen concentration. That will give
you the change in dissolved oxygen concentration, which is the net primary productivity. If one
gets a positive answer, that means that the producers in the water have produced more
oxygen than the consumers used during the time frame. If one gets a negative answer,that
means that the consumers used more oxygen via cellular respiration than the producer could
produce.
8.
Describe how the introduction of a non-native species destabilizes an ecosystem:
Competition: Non-native species may be more aggressive competitors than the
ones present. They may be more successful in competition for resources, whether it
is food, light, or space.
Predation: Some non-native species are more effective competitors and will kill
or consume native organisms, disrupting the ecosystem.
Genetic impact: Non-native species affect the genetic makeup by Gene flow. This
tends to reduce the genetic differences between the two species making them more
similar.
New interactions: Existing interactions are thrown off as the native species may
react differently to the non-native species. This can then compromise the existing
state of the native species.
9.
Eukaryote: an organism whose cells contain complex structures enclosed within membranes. The
defining structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear
envelope.
10. Diagram and describe a terrestrial food chain.
A terrestrial food chain describes the transfer of energy through organisms that live on land.
For example, in the diagram below, plants get their energy through sunlight, and animals such
as marmots, butterflies, grouse, and deer eat the plants (grass, flowers and berries). The
marmot is eaten by the red-tailed hawk or the grizzly bear, and the deer is also eaten by
grizzly bears. Also, the grizzly bear can eat flowers and berries directly. The seeds are eaten
by the grouse and the chipmunk, and the red tailed deer eats the chipmunk. When the
animals die, decomposers and detritovores feed on their flesh, and supply nutrients back into
the soil which the plants need in order to grow. Then the cycle starts all over again.
11. Describe how loss of a species destabilizes an ecosystem.
Answer: A loss of a species affects the food chain. For example, when a species (such as a
type of bird) has become extinct, the animals that prey on that bird will lose a source of food,
so they will have to eat other animals or plants. This will result in a shortage of (and could
possibly endanger) that particular animal or plant (since the bird isn't available to eat). Also,
the animals and plants that the extinct bird feeds on will be overpopulated because the
number of predators has been reduced. This will lead to instability in the ecosystem.
12. Heterozygote Advantage
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describes the case in which the heterozygote genotype has a higher relative fitness than either
the homozygote dominant or homozygote recessive genotype
Example: Sickle Cell Anemia
o Sickle-cell anemia is a genetic disorder that is caused by the presence of two recessive alleles.
o If a person with a heterozygote trait for sickle cell (Aa) for example, they do not show the
effects of the disease but they contain the recessive allele for sickle cell. This recessive allele
protects them from malaria.
13. Describe the transfer of energy through a food pyramid.
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Each level of a pyramid is called a trophic level.
Only 10% of energy from the previous trophic level is passed on to the next trophic level.
o For example, if a plant (autotroph) contains 100% of the original energy, the grasshopper that
eats the plant will only receive 10% of the original energy, the snake that eats the grasshopper
will only receive 1% of the original energy and so on.
14. Transformation
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Transformation is one of three basic mechanisms for genetic exchange in bacteria.
DNA that is outside the host cell is taken into a recipient cell where it is incorporated into the
recipient genome, changing the genetic makeup of the bacterium.
Artificial or Natural Transformation
o Natural: the active uptake of free DNA by bacterial cells and the heritable incorporation of its
genetic information.
o Artificial: In some cases DNA can be forced into these cells by chemical, physical, or enzymatic
treatment. This is especially important in genetic engineering, as artificial transformation is
essential for the introduction of genetically altered sequences into recipient cells.
15. Explain the difference between a habitat and a niche:
A habitat is the place where the organism lives, the niche is the job it has in the habitat.
16. Describe the different niches in a stable ecosystem:
What an organism eats, what eats it, where it lives, and any other influence that it has on the
environment. When it reproduces, how much offspring etc…
17. Niche Exclusion Principle- Every species has a niche or ecological role (how it
fits into the
ecosystem) and if there are two species with the same niche, then it leads to the elimination of
the inferior competitor/species.
18. Community- All the organisms that inhabit a particular area; an assemblage of
populations of different species living close enough together for potential interaction.
19. Give an example of competition:
A squirrel and a chipmunk both want to eat insects, limit each other.
defined as: a symbiotic relationship between or among living things for resources, such as
food, space, shelter, mate, ecological status, etc
20. Describe an example of Parasitism
The hookworm is a parasite that is consumed in uncooked pork that grows in a human's
digestive tract and absorbs nutrients through the food the human consumes, depriving the
host of necessary nutrients.
21. How is an organism's phenotype affected by genetics and environment ?:
An organism's behavior, traits, and appearance can all be considered part of its
phenotype. The environment can influence these. For example, the environment a bird lives in
can influence its behavior by what materials are available for it to construct a nest, or a bacteria
can be reddish because it lives in an iron-rich habitat. Genotype codes for appearance and
traits, so it affects phenotype. Genotype can determine fur color in cats, for example.
22. Describe a symbiotic relationship between fungi and plants
Mycorrizhae: fungus that inhabits the surface area of a plant's root, provides essential nutrients
and water to the plant via its high absorbative capacity, and, in some habitats, provides access
to previously immobilized phosphorous sources; The fungus helps the host plant absorb inorganic
nitrogen and phosphorus from the soil. Some mycorrhizal fungi also secrete antibiotics which may help
protect their host from invasion by parasitic fungi and bacteria.
23. Describe an example of predation
Lion (predator) captures, kills, and consumes a zebra (prey)
24. Explain Gross Primary Production
This is the total primary production of an ecosystem. This includes the amount of light energy
that is converted to chemical energy by photosynthesis per unit time. For aquatic ecosystems,
primary production is controlled by the amount of light and nutrients available. In terrestrial
ecosystems, temperature and moisture are the controlling factors.
25. Commensalism
It's a symbiotic relationship in which one organism benefits but the other is neither helped or
harmed.
Example: More than 150 bacterial species live on the surface of our skin. We provide food for
them, like oils that comes from our pores, and a place to live. But the bacteria neither help or
harm us.
26. Describe how a monoculture destabilizes an ecosystem:
A monoculture is the practice of producing/growing one single crop in a large area. If a
uniform crop is susceptible to a pathogen, the disease is more likely to spread faster in that
area and wipe out the entire population. The normal interactions and the competition that occur
within the population help to restrict harmful plants and/or insects but with a monoculture, you
have to control the pests/weeds. Monoculture also depletes the nutrients in the soil which
increases the use of fertilizer.
27. Describe how loss of tropical forests has global consequences:
Deforestation threatens the existence of species and the biological diversity of the globe.
Tropical rainforests afford humans valuable services like erosion prevention, flood control,
pollination, and water treatment. Many people rely on natural resources for their everyday
survival and deforestation limits the availability of renewable resources such as timber,
medicinal herbs, nuts, fruits, and animals (game). Deforestation also drives climate change.
Forest soil is moist but without trees for sun protection, the soil will dry out. Trees also help
perpetuate the water cycle by returning water vapor back into the atmosphere. Without trees,
larger amounts of greenhouse gases can enter the atmosphere which will increase the speed
and severity of global warming.
28. Discuss the evidence supporting the endosymbiotic theory:
Endosymbiotic theory describes the idea behind the formation of eukaryotic cells and the theory behind
why mitochondria and chloroplast have there own DNA. It is believed that mitochondria was originally
a parasite engulfed by an ancestral prokaryote and never digested, but eventually in stead of harming the
cell the mitochondria formed a mutualistic relationship. This parasite turning beneficial has been seen
through out science many times. The host benefits from the nutrients released by the mitochondria or
chloroplast and the prokaryote revives protection from an ever more aerobic world.
29. Describe an example of commensalism:
Commensalism is when two organisms live in close contact; where one organism is helped and the
other one is neither helped nor harmed. A common example is the shark and the pilot fish. The pilot fish
eats the scrapes from the shark’s food but the shark itself is neither harmed nor benefited by this.
30. Symbiosis-An interaction between two different organisms living in close physical association, typically to
the advantage of both. For example; parasitism, commensalism, and mutualism
31. Explain what a keystone species is. Give an example.a species that plays a critical role in maintaining the structure of an ecological community and whose
impact on the community is greater than would be expected based on its relative abundance or total
biomass. An example is alligators and otters.
32. Eubacteria:
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Means "true bacteria;" includes all bacteria except archae bacteria.
these bacteria from the domain Bacteria
Prokaryotic organisms that lack membrane enclosed nucleus, are mostly unicellular, have
DNA in single circular chromosome, and have peptidoglycan on call wall if it has a cell wall.
Most familiar bacteria of medical and economic importance.
33. Describe a symbiotic relationship between bacteria and animals:
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Mutualistic: bacteria that live in our intestines: E. coli
Parasitic: Lyme disease, caused from bacteria transferred by ticks. produces arthritis, heart
disease, and nervous disorders.
34. Cooperation/cooperatively: an act or instance of working or acting together for a common
purpose or benefit; joint action
Examples: mutualism; both organisms benefit from the other, such as termites and the
bacteria that live in their digestive tract allow the termite to digest cellulose
This is when components of a system seem to communicate ( like a school of fish).
It also can be important in cell to cell signaling and more complex processes regulating the
behavior of cells.