APES Unit 1: The Living World: Ecosystems Concept Study Notes

A set of practice flashcards covering key concepts from APES Unit 1: Ecosystems, including ecosystem interactions, biotic/abiotic factors, biomes, biogeochemical cycles, productivity, trophic levels, and energy flow.

What effect does the availability of resources have on species interactions?

Resource availability shapes which interactions occur and their strength, influencing competition, predation, and symbiotic relationships.

Define predation and give two examples.

Predation is one organism consuming another. Examples: wolves preying on deer; hawks preying on mice.

Define intraspecific competition and give two examples.

Intraspecific competition is competition between members of the same species. Examples: two male deer competing for mates; algae strains competing for limited nutrients.

Define interspecific competition and give two examples.

Interspecific competition is competition between different species. Examples: warblers and thrushes competing for insect prey; oak and maple trees competing for light.

Define competitive exclusion and give two examples.

Competitive exclusion occurs when one species outcompetes another for the same resource, leading to the other's local elimination. Examples: Paramecium aurelia outcompeting P. caudatum in the same environment; two similar fish species competing for the same prey, with one dominating.

What is a biological niche, and give two examples.

A niche is the role and position a species has in its ecosystem, including how it uses resources. Examples: a woodpecker foraging on bark; a cactus adapted to arid desert conditions.

Define resource partitioning and provide two examples.

Resource partitioning is division of resources to reduce competition, often by using different parts of the resource or at different times. Examples: multiple warbler species feeding at different heights in a single tree; different herbivores feeding at different plant parts.

Describe mutualism and give two examples.

Mutualism is a relationship where both species benefit. Examples: bees pollinating flowers; mycorrhizal fungi aiding plant nutrient uptake.

Describe commensalism and give two examples.

Commensalism is when one species benefits and the other is unaffected. Examples: barnacles on whales; epiphytic orchids growing on trees.

Describe parasitism and give two examples.

Parasitism is a relationship where one organism benefits at the expense of the host. Examples: tapeworms in intestines; fleas on dogs.

What is an abiotic factor?

A non-living component of the environment (e.g., temperature, pH, moisture, salinity).

What is a biotic factor?

A living component of the environment (e.g., plants, animals, microorganisms).

Give an example of an abiotic factor affecting a biotic factor.

Soil pH affecting nutrient availability and plant growth.

Give an example of a biotic factor affecting an abiotic factor.

Beavers building dams can alter water flow and the local hydrology.

Give an example of a biotic factor affecting a biotic factor.

Predation reducing prey populations, which in turn affects predator numbers.

What abiotic factors should be described when detailing terrestrial biomes?

Geography, latitude, altitude, nutrient availability, and soil; include a climatogram of average precipitation and temperature.

Name the major terrestrial biomes listed in the notes.

Taiga, temperate rainforests, temperate seasonal forests, tropical rainforests, shrublands, temperate grasslands, savanna, desert, tundra.

What is the purpose of including climate visuals for biomes (climatogram, photos)?

To show how precipitation and temperature patterns shape biome characteristics, plus visuals of land, plants, and animals.

List the processes in the carbon cycle as requested.

Photosynthesis, respiration, decomposition, combustion.

Which carbon cycle processes are biological?

Photosynthesis, respiration, and decomposition are biological processes; combustion is not.

Which carbon cycle process must be reduced to help mitigate climate change?

Combustion (especially burning fossil fuels) must be reduced.

What are the two major carbon sinks (storage) in the carbon cycle?

Oceans and geological reservoirs (sedimentary rocks/long-term sediments).

What percent of the atmosphere is carbon?

Approximately 0.04% (about 400 parts per million).

Name the five processes of the nitrogen cycle.

Nitrification, nitrogen fixation, assimilation, ammonification, denitrification.

What organism is key to nitrogen fixation, and where?

Rhizobium bacteria in legume root nodules fix nitrogen into usable forms.

What is the major reservoir of nitrogen?

The atmospheric reservoir, N2, is the largest reservoir of nitrogen.

Describe the phosphorus cycle and mention the term guano.

Phosphorus cycle involves weathering of rocks releasing phosphate, uptake by organisms, assimilation, and return via decomposition; guano is a significant source of phosphate.

What is the major reservoir of phosphorus?

Phosphate rocks and related sedimentary deposits.

Why is phosphorus often a limiting factor in ecosystems?

Phosphorus has no gaseous phase, moves slowly through the environment, and is often limited in soils, constraining primary production.

List the steps of the hydrologic (water) cycle.

Evaporation, transpiration, condensation, precipitation, infiltration, percolation.

Why are trees/forests important to the water cycle?

Transpiration adds atmospheric moisture; roots promote infiltration and reduce runoff, helping regulate the water cycle.

What is the major reservoir of water in the hydrologic cycle?

Oceans (the world’s largest reservoir of liquid freshwater).

Define Gross Primary Productivity (GPP).

The total amount of carbon fixed by photosynthesis in a given area and time before subtracting plant respiration.

Define Respiration (R) in plants.

The metabolic process where plants consume some of the fixed carbon for their own energy needs, releasing CO2.

Define Net Primary Productivity (NPP).

NPP = GPP − R; the amount of carbon stored as plant biomass (energy available to higher trophic levels).

Write the equation for Net Primary Productivity.

NPP = GPP − R.

List the trophic levels and brief definitions.

Producer: organisms that make their own energy (plants); Primary consumer: herbivores; Secondary consumer: carnivores that eat herbivores; Tertiary consumer: top carnivores; Decomposers: break down dead matter; Detritivores: ingest detritus; Detritus: non-living organic matter.

Explain the 10% rule of energy transfer in ecosystems.

Approximately 10% of energy stored in one trophic level is transferred to the next; about 90% is lost as heat or through metabolic processes.

How is the 2nd Law of Thermodynamics related to food chains and the 10% rule?

Energy becomes more dispersed and less usable as it moves up trophic levels, with most energy lost as heat at each transfer.

Differentiate a food chain from a food web.

A food chain shows a single linear pathway of energy transfer; a food web is a network of interconnected food chains showing multiple pathways for energy flow.

Construct a basic food web with at least 2 producers, 2 primary consumers, 2 secondary consumers, and 1 top predator.

Example: Producers: grasses and algae; Primary consumers: grasshoppers, zooplankton; Secondary consumers: small birds, small fish; Top predator: hawk or larger fish; Arrows indicate energy flow from sun to producers to consumers to top predator, with decomposers breaking down waste.