AP Biology Unit 8

Behavioural response to the environment

Observable actions/decisions made by individuals in response to environmental cues.

Example: moving to warm up

Physiological response to the environment

Automatic, internal adjustments to adapt to external stimuli.

Example: shivering when cold

Photoperiodism

Response of an organism to lengths of light and dark periods.

Example: geese timing migration

Phototropism

Directional growth of plants in response to light.

Taxis

Innate response where an organism moves toward (positive) or away (negative) from a external stimulus.

Directed, purposeful movement.

Kinesis

Non-directional, random movement of an organism in response to a stimulus. The stimulus make the organic change speed or rate of turning.

Helps organism reach a favourable environment.

Nocturnal and diurnal

Nocturnal - active during night, sleep during day.

Diurnal - active during day, sleep during night.

Communication mechanisms

Produce changes in behaviour of other organisms, leads to differential reproductive success.

Visual signals, Audible signals, Electrical signals, Chemical signals (plants release chemicals when eaten to warn others), Tactile (physical contact),

Cooperative behaviours

Organisms working together to survive.

Natural selection

Favors signals and responses that increase survival and fitness of the organsims

Endotherms

Use external energy such as the sun to maintain body temperature. Do not have sufficient internal mechanisms.

Ectotherms

Use energy generated internally through metabolic processes to maintain body temperature

Metabolic rate

Amount of energy used by an organism over a specific time

More active organisms have a higher metabolic rate

Mass specific metabolic rate

Energy used by an organism per unit of body mass

Smaller organisms have a higher mass specific metabolic rate because SA:V ratio is high, they loose heat more quickly and need to restore it.

Net gain of energy

Energy storage, growth

Net loss of energy

loss of mass, death

Trophic levels

An organisms position in a food web/chain based off the organisms food and energy sources.

Producers, primary, secondary, tertiary, quaternary

Autotrophs

Producers, produce food from inorganic materials from their environments.

Photoautotrophs

Use energy from sunlight

Chemoautotrophs

Use chemical energy from chemical reactions

Heterotrophs

Cannot produce their own food and must consume other organisms for energy

Decomposers

Break down dead organisms into simpler nutrients. Recycle essential nutrients back into the ecosystem.

Food chains

Linear sequence of organisms, shows the energy transfer between them

Food web

Network of food chains, multiple paths of energy flow

Biomass

Total mass of all living organisms at a specific trophic level.

Energy is stored in biomass

Only 10% of biomass stored in a trophic level is converted into biomass of the next.

90% is lost as respiration, heat, or waste.

Bottom up regulation

Population sizes and biomass are controlled by resource availability at lower trophic levels

Top down regulation

Predators control population sizes and biomass of organisms at lower trophic levels.

Biogeochemical cycles

Processes through which essential elements are circulated between the abiotic and biotic parts of an ecosystem

Evaporation

Water vapour rises to atmosphere because it got heated in oceans, lakes, and rivers by the sun.

• Transpiration: plants release water vapour.

Condensation

Water vapour rises and cools, turning into water and forming clouds.

Precipitation

Clouds become heavy with water so it falls down to the earth.

Collection

Water collects in oceans, rivers, streams or soaks into the ground (infiltration).

Photosynthesis

Plants absorb CO₂ from the atmosphere and convert it to glucose and oxygen

Consumption

Animals eat plants/other animals, moving the carbon through the food chain.

Respiration

Living organisms break down glucose and release CO₂ into the atmosphere when they breathe.

• Decomposition: Bacteria and fungi break dead organisms down releasing CO₂ into the soil/atmosphere.

Combustion

Carbon is released into the atmosphere when organic matter/fossil fuels are burned.

Nitrogen fixation

Atmospheric nitrogen is converted into NH₃ (ammonia) by microorganisms in soil/aquatic environments

Nitrification

Soil bacteria convert ammonia into nitrite (NO₂^-) then to nitrate (NO₃^-)

Assimilation

Plants absorb nitrogen compounds (primarily nitrates and ammonium), convert them to AA.

Ammonification

Bacteria and fungi decompose organic nitrogen from dead organisms and waste, converting to ammonia or ammonium. Can re-enter nitrification process.

Denitrification

Denitrifying bacteria convert nitrate back into nitrogen gas, which goes back to the atmosphere.

Weathering + erosion

Rocks (which contain phosphorus) release it as phosphate ions due to breaking from wind, rain and chemical weathering.

Into soil/water

Absorption

Producers take in phosphate, incorporating them into organic molecules

Consumption

Animals eat producers, getting phosphorus

Decomposition (P)

When organisms die, decomposers break organic matter, releasing phosphorus into soil.

Sedimentation

Phosphorus sinks to the bottom of water bodies, forming new rock layers.

Reproduction

Based off energy availability and metabolism.

• Some organisms alternate between sexual and asexual reproduction based off energy availability.

• organisms with faster metabolisms reproduce more because they acquire and process energy more quickly, mature faster.

Organism

A single living entity

Population

A collection of organisms that are of the same species

Community

A group of interacting populations (species) that live in the same habitat

• Change over time based off of the interactions of the populations

Ecosystem

Consists of all living organisms in the area (biotic) as well as non living things (abiotic)

• Biotic and abiotic factors interact

Biome

A large, geographical area.

Competition

Organisms use the same limited resource such as food, habitat, and mates.

Interspecific - different species

Intraspecific - same species

Predator/prey

Predators rely on prey for food and control their populations.

As number of prey increases, number of predators follows. leads to decrease in prey.

Trophic cascades

Changes at one trophic level influence others in the food web.

Niche partitioning

Competing species coexist by using shared resources differently.

Symbiotic relationship

Ways two species can interact

Parasitism

One organism benefits. one organism is harmed

Commenalism

One organism benefits, the other isn’t harmed nor benefited

Mutualism

Both organisms are benefited

Biodiversity

The variety of living things in the world, ecosystem, or a habitat.

Ecosystems with greater biodiversity are more resilient and can adapt to environmental changes.

Keystone species

Organism that has a disproportionately large impact on its ecosystem

• Disproportionate because their influence is greater than their abundance would suggest.

Maintains ecosystem stability and biodiversity, holding it together

Heterozygote advantage

Individuals with two different alleles have higher fitness than homozygous individuals.

Invasive species

Organisms that aren’t native to an ecosystem

• Outcompete native species, bringing harm to the ecosystem.

Human impact

Humans accelerate changes in ecosystems/biodiversity

• Accelerates mean that we make it happen at a faster pace than natural processes.

Biomagnification

Process by which toxic substances become increasingly concentrated at higher trophic levels.

• Tiny organisms absorb little mercury, little fish eat lots therefore accumulating mercury, large fish eat the a lot of small fish accumulating even more mercury.

Eutrophication

Process by which nutrients accumulate in bodies of water and cause excessive algae growth that depletes oxygen from the water.

1) Excess nutrients enter the water

2) Algae grows and blocks sunlight from reaching underwater plants

3) Plants die, so they are unable to oxygenate the water.

4) Bacteria decompose the dead plants, using up oxygen

5) Any life dies

Geological & meterological

Geological and meteorological events are drivers of change in ecosystems

Density dependant factors

Limit population growth based on its size.

• increases with increase in population

Density independant

Affect population size regardless of density

R-selected

Species that thrive in unstable environments and produce many, low-investment offspring.

K-selected

Species that thrive in stable environments and produce few, high-investment offspring.