Honors Biology: Ecology Quizlet
Section 1: Ecological Organization & Earth’s Spheres
Study of the interactions between organisms and their non-living environment.
Group of similar organisms that can interbreed and produce fertile offspring.
A group of the same species interacting and living together in a specific area.
Different populations interacting and living together in an area.
The living community interacting with the non-living environment.
A large group of ecosystems with a characteristic group of communities and a particular physical environment.
The parts of the Earth where all life exists.
Living organisms in an ecosystem (e.g., deer, bacteria, grass, fungi).
Non-living factors in an ecosystem (e.g., sun, water, pH, weather, temperature).
The thin layer made up of a mixture of gases suspended in the air that surround the Earth.
A sphere that includes the liquid ocean, inland water bodies, and groundwater.
A subset of the Hydrosphere that consists entirely of frozen water.
A sphere that includes the solid Earth; the core, mantle, crust, and soil layers.
Section 2: Energy Flow & Feeding Relationships
Each step or role in a food chain.
Organisms that make their own food/glucose automatically.
Converts light energy into chemical energy stored in the bonds of glucose/food.
Transfer of chemical energy from inorganic molecules to glucose (e.g., chemosynthetic bacteria).
Organisms that ingest food to obtain the chemical energy needed to build their bodies.
An animal that does not kill its own food, but instead feeds on animals that are already dead.
A predator hunts and consumes living prey. The prey is the hunted organism.
Organisms that break down dead organisms and return nutrients to the soil by secreting digestive enzymes (e.g., bacteria and fungi).
Energy cannot be created or destroyed, only transformed from one form to another. (Plants transform light into chemical energy; they do not create it).
Every energy transfer increases the disorder (entropy) of the universe. In ecology, this means energy transfers are never 100% efficient due to heat loss.
A linear sequence that shows energy transfer from autotrophs to heterotrophs. Arrows point in the direction of energy flow.
No! Energy only flows in one direction and must be constantly replenished by the sun. Elements/matter, however, are recycled.
Section 3: Food Webs & The 10% Rule
Many interacting food chains that show more biodiversity and complex feeding relationships in an ecosystem.
The amount of organic molecules stored in cells (tissues), available to be consumed by the next trophic level.
Only about 10% of the energy from an organism on one trophic level can be passed on to an organism on the next level.
It is used during cellular respiration, metabolism, lost as waste, and continuously lost to the environment as HEAT.
Because they break down ALL types of dead organisms, arrows from all trophic levels ultimately point to the decomposers.
Shows the amount of energy available at each trophic level. Energy decreases significantly as you move up the pyramid.
Shows the amount of living tissue (potential food) at each trophic level. Biomass decreases as you move up.
Shows the number of individual organisms at each trophic level. Generally, population size decreases as you move up (there are more producers than consumers).
There is rarely a level greater than a quaternary (4th degree) consumer because so little energy is available by the time it reaches the top of the chain.
The bonds that store the most energy in organic compounds are between Carbon-Carbon (C-C) or Carbon-Hydrogen (C-H) atoms.
Section 4: Biomagnification & The Carbon Cycle
Organisms at higher trophic levels have a greater concentration of toxins stored in their tissues because the toxins cannot be metabolized.
Examples include DDT (pesticides), PCBs, and mercury. Top predators like large fish or birds of prey carry the highest loads.
Constantly recycle matter (elements like C, N, P) between the biotic & abiotic factors in an ecosystem. Matter is conserved, not created or destroyed.
Producers remove Carbon (as CO2) from the atmosphere to make glucose (C6H12O6) and release O2.
Eukaryotes (plants and animals) use O2 and break down glucose, releasing Carbon (as CO2) back into the atmosphere.
Bacteria and fungi return carbon to the soil as they break down organic matter. They also conduct respiration, releasing CO2.
Consumers eat other organisms and take in their carbon compounds, passing it through the food chain.
Burning fossil fuels releases massive amounts of stored CO2 back into the atmosphere.
Removal of trees by clear-cutting or burning prevents CO2 from being removed from the air by photosynthesis.
Section 5: The Nitrogen & Water Cycles
All organisms need Nitrogen (N) to build amino acids, proteins, and nucleic acids (DNA and RNA).
Convert unusable Nitrogen gas (N2) from the atmosphere into Ammonium (NH4+). Found in soil and in a mutualistic relationship with the roots of legumes.
Convert Ammonium (NH4+) into Nitrates (NO3-). Nitrates are the usable form absorbed by ALL producers to build proteins.
Convert Nitrates (NO3-) back into Nitrogen gas (N2), removing excess N from the ecosystem and balancing N-fixation.
A mutualistic relationship where N-fixing bacteria live in legume roots, gaining a habitat/glucose, while the plant receives usable nitrogen.
Addition of excess nutrients (N, P, K) to a body of water from fertilizer or sewage runoff, leading to producer overgrowth and algal blooms.
Algae blocks sunlight, plants die, and decomposers use up all the Oxygen (O2) in the water to break them down, resulting in fish kills and “dead zones.”
Liquid water changes to water vapor (gas) from oceans, lakes, and streams.
Water evaporates directly from plants through the stomata of their leaves.
Condensation: water vapor changes to tiny liquid droplets (clouds). Precipitation: water falls to the surface as rain, snow, sleet, etc.
Section 6: Biodiversity & Species Interactions
Refers to both species diversity (variety of species in an area) and genetic diversity (variety within a single species).
Provides medicines, CO2 and O2 balance, food chain stability, varied food sources, shelter, and predator/prey population stability.
Genetic variations within a species provide unique adaptations that allow populations to withstand disease and resist environmental change.
A relationship in which two species live closely together.
A symbiotic relationship where Species A receives a benefit, and Species B is not affected.
A symbiotic relationship where both Species A and Species B receive a benefit.
A symbiotic relationship where Species A receives a benefit, and Species B is harmed.
An organism’s specific role or “job” in an ecosystem.
No two species can occupy the exact same niche at the same time, or else they will COMPETE! (e.g., Paramecium populations grown together).
Section 7: Ecological Succession
Slow, gradual changes in an ecosystem where species compete and replace one another until a stable climax community is reached.
The first species to populate an area. They often help break down rock to form soil.
A classic pioneer species formed by a mutualistic relationship between fungi (decomposers) and autotrophs (algae or cyanobacteria).
Fungi get sugar/food from the autotroph. The autotroph gains protection from water loss and attachment to the rock.
The most stable, biodiverse community following the process of succession. It remains until a disturbance occurs.
Gradual establishment of an ecosystem beginning from bare rock, with NO life or soil. Caused by volcanic eruptions (lava) or retreating glaciers.
Gradual establishment of an ecosystem in an area where soil already remains. Caused by farming, human disturbances, or natural disasters like fires.
Section 8: Population Dynamics & Limiting Factors
Changes in population size, density, dispersion (spatial patterning), and age structure over time.
J-shaped curve showing rapid population increase due to constant reproduction, unlimited resources, and no predation or disease.
S-shaped curve showing growth that slows and levels off as resources become more limiting and carrying capacity is reached.
The maximum number of individuals in a population that an ecosystem can support based on limited resources.
Factors that restrict population growth when the population’s density is high (e.g., disease, predation, parasitism, competition).
Factors that limit all populations in a similar way, regardless of their density (e.g., weather events, natural disasters, human activities).
A nutrient that is scarce and must be added to an ecosystem to increase producer growth. (N, P, and K are naturally limited because they move slowly).
Resources that regenerate and are quickly replaceable (e.g., trees, water, solar energy).
Making use of decomposers to add nutrients to the soil from compost and yard waste. It reduces reliance on fertilizers and saves landfill space.
Miscellaneous
The physical size of the area in which a population lives.
The number of individuals per unit area. It varies depending on species type, trophic level, and ecosystem characteristics.
The proportion of individuals in each age group (pre-reproductive, reproductive, post-reproductive) of a population.
Has grown rapidly over the past hundreds of years due to improved agriculture, industrialization, sanitation, and medication.