AP Bio Ecology (Unit 8)

Ecology

study of relationships between living organisms and their environment

Biotic factor

any living factor in an organism’s environment

Abiotic factor

any nonliving factor in an organism’s environment

Individual

a single organism

Population

a group of organisms of the same species

Community

all the populations of species (all biotic factors)

Ecosystem

biological community and all abiotic factors that affect it

Biome

a group of ecosystems that share the same climate and have similar types of communities

Biosphere

the layer of Earth that supports life

Habitiat

the area where an organism lives

Niche

the role or position that an organism has in an ecosystem

Competitive exclusion principle

suggests that species with identical niches cannot coexist forever, and competition will result in natural selection

Niche partitioning

species occupy different niches to avoid competition

Photoperiodism

reaction of plants to the length of a night or dark period

Phototropism

growth of a plant in response to light (going towards sunlight)

Diurnal animals

active during daylight

Nocturnal animals

active during night

Crepuscular animals

active during twilight

Taxis

directed movement of an organism in response to a stimulus (can be toward or away from stimulus based on if it’s positive/negative)

Kinesis

undirected movement of an organism in response to external stimulus

Fight-or-flight response

organism quickly chooses to fight or to flee in response to stressful stimulus

Aposematism

the advertising by an animal to potential predators that it is not worth attacking or eating

Innate behaviors

behaviors that are developmentally fixed and closely controlled by genes (little to no environmental influence)

Learned behaviors

behaviors that are present as a result of experience

Altruistic behaviors

behaviors that lower the fitness of the individual but increase the fitness of another individual

Autotroph

organism that makes its own food (aka producers)

Heterotroph

organisms that get food and energy from a source (aka consumers)

r-selection

many offspring with low survival rates

K-selection

few offspring with high survival rates

Annual plants have ____ growing season

one

Biennial plants have _____ growing seasons/years

two

Perennial plants have life cycles ______

longer than two years

Metabolism

energy usage

Endotherm

organism that maintains homeostatic body temperature using energy

Ectotherm

organism that relies on external sources of heat to maintain its body temperature

Trophic level

indicator of feeding level or position in the food chain

10% rule

Each level only has ~10% of the energy of the previous level

(this is because energy is lost as heat when you go up the pyramid)

Biomass

how much matter is made up by living organisms

Biogeochemical cycles

flows of nutrients from living to nonliving components of the Earth

Water cycle (hydrologic cycle) processes

• precipitation (water vapor falls)

• evaporation (liquid to gas)

• transpiration (plants release water into air)

• condensation (gas to liquid)

Carbon cycle processes

• photosynthesis (plants make their food with co2)

• cellular respiration (breaks down organic compounds and releases co2)

• Decomposition (decay of organisms by decomposers releases co2)

• Combustion (burning fossil fuels releases co2)

Nitrogen cycle processes

• nitrogen fixation – Bacteria or lightning convert atmospheric nitrogen (N₂) into ammonia (NH₃) or ammonium (NH₄⁺), which plants can use.

• nitrification – Nitrifying bacteria convert ammonia into nitrites (NO₂⁻) and then into nitrates (NO₃⁻), a more usable form for plants.

• assimilation – Plants absorb nitrates from the soil and use them to build proteins; animals get nitrogen by eating plants or other animals.

• ammonification – Decomposers break down dead organisms and waste, releasing ammonia or ammonium back into the soil.

• denitrification – Denitrifying bacteria convert nitrates back into nitrogen gas (N₂), releasing it into the atmosphere and completing the cycle.

Phosphorus cycle processes

• rock weathering (releases phosphate into soil and ground water)

• producers take in phosphate

• excretion (returns phosphate back to soil via release of waste by organisms)

• decomposition (returns phosphates back to soil)

What macromolecules require carbon?

carbohydrates, lipids, proteins, nucleic acids (all)

What macromolecules require nitrogen?

proteins and nucleic acids

What macromolecules require phosphorus?

nucleic acids and phospholipids