Unit 3: Ecology & the Living World
Study Guide Questions
ENDANGERED/EXTINCTION
1) What is the biggest threat to biodiversity?
Habitat destruction
2) What are characteristics of organisms that could lead to increased risk of
endangerment?
Limited distribution, being a specialist, Small pop. size
3) What is a specialist species?
Occupy narrow niches, have risk of extinction
4) What are causes of the decline of the Whooping Crane?
Habitat loss due to urbanization, wetland destruction, fossil fuel extraction. Each
could lead to loss of food resources, food web disruption, loss of
breeding/nesting/migration habitat.
Hunted for feathers, meat, eggs, skins, trophies, sport or unintentially
5) What are ways that endangered species can be/are being protected?
Legislation:
Endangered Species Act – cannot be hunted, killed, collected, harmed or injured
Clean Water Act – protects wetlands
Migratory Bird Conservation Act – protects migratory species
Ban use of pesticides like DDT
Creation of wildlife refuges
Other:
Captive breeding/incubation of eggs – establishing experimental populations,
teaching alternative flyways
Public Education – raise public awareness of endangered species status
6) What is one ecological reason why endangered species should be protected?
Maintain biodiversity for evolutionary value; for genetic diversity value; species
may be a keystone species
Endangered species have a niche value, where other species may rely on it (give
example)
7) What is one economic reason why endangered species should be protected?
Tourism; Reestablish population for commercial harvest; Economic sanctions
against countries who are not enforcing endangered species laws
EVOLUTION/GENETICS
1) Describe how evolution works.
Cannot occur within an individual organism. Evolution occurs within a population of
a species; the allele frequencies change over time. Evolution occurs through natural
selection of traits. Offspring with more advantageous traits will survive, reproduce
and thus their genes will be more prevalent.
2) What is the difference between a K-strategist species and a r-strategist species?
K – large body, long life, produce few offspring
r – small body, short life, produce many offpsring
3) How can you increase the genetic resistance to a disease of a crop?
Genetic uniformity of a crop decreases the crop’s resistance to a disease. Therefore,
by crossing a crop plant with its ancestral species will increase resistance.
4) How is interspecific competition different than intraspecific competition?
Interspecific comptetition occurs when 2 similar species in the same location are
occupying similar niches. If the niches overlap too much then it could result in
migration or restricting the range of one species.
Intraspecific competition is where members of the SAME species compete for the
same resources.
BIODIVERSITY
1) What is fragmentation? How does it affect biodiversity.
Reducing area’s size and supplanting wildlife with human habitation; reduces
biodiversity. Organisms could be cutoff from food source, habitat, water source, etc.
2) What is the difference between population density and species richness?
Richness involves sampling an area and counting how many different types of
species there are in the area. Density only refers to population of a species per unit
area.
3) What is productivity in an ecosystem? How can it be measured?
Refers to rate of generation of biomass in an ecosystem. Primary production is
dominated by plants and algae through photosynthesis, and can be measured in an
aquatic ecosystem by measuring dissolved oxygen levels
4) What is net primary production? How could this be measured in aquatic plants?
The gain produced by photosynthetic organisms after they have used some energy
for their life processes (NET PRODUCTIVITY = Gross productivity – Respiration
costs)
5) What are limiting factors? Give examples.
Limits the growth or development of an organism or population, which causes the
population to decrease in size. Examples: Food, shelter, water, space, sunlight, temp.
6) Describe the characteristics of a fish population that exist in fisheries. Describe the
genetic diversity. How can fisheries affect the nearby aquatic ecosystem?
Individuals would be very similar genetically and have a higher risk for carrying
disease because of small enclosed space. Fish can escape from containment areas
and also impact water quality negatively due to waste production. Also dissolved
oxygen levels could decrease in the area.
TROPHIC LEVELS/FOOD WEBS/ECOSYSTEMS
1) What is the ultimate source of energy on earth for terrestrial ecosystems?
Sun
2) Describe how much energy is transferred and how much energy is lost between
each trophic level.
10% max is transferred; 90% min. is lost
3) What is a trophic level? Which types of organisms are higher on the trophic level
pyramid? Which types are lower on the pyramid?
Trophic levels represent energy levels of organisms in a food chain. Producers are
lower, Herbivores just above producers, carnivores are highest.
4) If a community wants to produce the most calories for human consumption, what
agricultural practice should they consider carrying out?
Planting grains rather than raising meat, because it is more efficient.
5) How is a biomass pyramid different than a trophic level pyramid?
Biomass – refers to total dry mass of organisms
Trophic – refers to energy levels that are transferred
Both look very similar.
6) Describe how biomagnification works. Which organisms would have the most
concentrated levels of toxins?
Toxins move through the food chain and become more concentrated and thus more
harmful to organisms. The organism at the top of the food chain would have the
most concentrated levels of toxins.
7) Describe the importance of a keystone species. Give an example.
Keystone species drive an ecosystem and many other species are dependent on it.
Altering this species greatly impacts the system. Example: Sea otter in a kelp forest
prevents sea urchins from eating the kelp roots which would kill the kelp.
8) What is nitrogen fixation? What types of organisms carry this out.
Process of taking nitrogen gas from the air (N2) and turning it into ammonia (NH3)
which is more usable by other organisms. Prokaryotes like bacteria carry this out.
Ex: Rhizobia
9) What is denitrification?
Process where bacteria use nitrates (NO3) for their own respiration instead of
oxygen to release nitrogen gas (N2) back into the atmosphere.
10)Where do heterotrophs get their energy from?
Since heterotrophs feed on other organisms, they ultimately get their energy from
carbon compounds or organic molecules.
11)How is natural eutrophication different than human induced eutrophication?
Natural eutrophication takes place over many years, while human induced
eutrophication may only take several years. Natural eutrophication leads to a
productive aquatic ecosystem, while human induced usually leads to algal blooms
which ends up removing dissolved oxygen which results in fish kills.
12)Describe how commensalism is different than mutualism. Give an example of each.
Commensalism – one organism benefits, the other is unaffected
Examples: Remoras on sharks, Barnacles on whale, Moss on a tree
Mutualism – Both organisms benefit
Example: Bees and flowers
13)How is parasitism different than predation? Give an example of each.
Parasitism – one organism benefits, one is harmed but not killed usually
Example: Ticks suck blood from deer as food; ticks carry disease
Predation – One organism feeds on another, which results in death
Example: Lion eats buffalo
14) What is competition between organisms?
When two organisms compete for a resource, like space, which can lead to one
organism being displaced and the most fit organism emerging.
15)How is symbiosis different than mutualism?
Mutualism is a specific type of symbiosis.
16)Why is vegetarianism good for the environment?
Growing grains are more efficient than raising livestock for meat. Growing grains
uses less water, destroys less habitat, contributes less to global warming, and does
not erode soils or cause desertification if sustainable agricultural practices are used
17)Why is vegetarianism good for your personal health?
Reduced risk of heart disease, clogged arteries, diabetes, cancer, etc.
Reduced exposure to hormones, steroids, antibiotics, pesiticides, heavy metals
Reduced risk of infections/diseas like salmonella, E. coli, parasitic worms
18)What factors have lead to the world hunger crisis?
Poverty especially in developing nations; unequal distribution of available food
supplies; decline in arable land; increasing population rate growth; etc.
19)Why is it more efficient to produce grain for human consumption than meat?
Due to 10% rule, vegetarians eat lower on the trophic level pyramid wher they can
obtain more energy (kilocalories). Raising meat requires larger input of energy
because meat eaters feed at higher trophic levels.
20)Why is raising livestock for meat production harmful to the environment?
Overgrazing of land – desertification, increased erosion, nutrient loss
Pollution of waters from animal waste – contamination of ground water,
eutrophication which leads to fish kills
Fencing/Deforestation – loss of habitat, habitat fragmentation, biodiversity loss,
erosion, nutrient loss
Methane production from livestock – contributes to global warming
Livestock requires more water than grains – water depletion/shortage
BIOMES/SUCCESION/ECOSYSTEMS
1) Describe ecological succession. What events can lead to a cycle to restart?
Life cycle of a community based on the events in climate, organism, natural
disasters, fires, man-made events, etc. in the area.
2) What is an old growth forest? Where is the largest old growth forest in the US?
Attained old age without disturbance, known as climax community, diverse wildlife
and trees, more large trees. Alaska has the largest in the U.S.
3) What are some main climate factors that lead to different types of biomes across the
world?
Different climates lead to different communities of organisms, especially vegetation.
Temperature and precipitation are main factors. More precipitation occurs in forest
ecosystems compared to grasslands, even though both can be found at the same
latitude.
4) How is a deciduous forest different than a boreal forest?
Deciduous – 4 distinct seasons w/oaks, elms, etc.
Boreal – coniferous trees, mostly pines; in colder climates (AKA Taiga)
5) What is the process of desertification? Which continent has experienced
desertification the most?
Degrading of land into dry/arid area. Australia.
6) What is an invasive species? Why do invasive species thrive?
A species that has been introduced (usually by humans) and thrives in the new
habitat because they do not have natural predators.
7) What are abiotic changes that could occur to an ecosystem when an invasive species
takes over?
Nutrient levels in soil/water could change
Erosion of soil could increase
Soil pH could change
Soil could become more compacted/aeration decrease
DESIGN A CONTROLLED EXPERIMENT
1) Design a controlled experiment to test whether the weed killer Round Up changes a
garden ecosystem at your local park. Make sure to identify what you will measure, include
a hypothesis, and describe the data you will collect and how you will collect it.