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ap bio unit 8 review NOTES
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ap bio unit 8 reviewBasics of Ecology
How Organisms Respond to Environmental
Changes
● survival of organism: depends on their ability to respond to changes in the
environment
○ responses to changes can be behavioral or physiological
● stimulus: change in the environment that triggers a response
● behavioral response: refers to how animals cope or deal with changes in their
environment by changing their behavior
● physiological response: refers to how animals cope or deal with changes in their
environment by changing their physiological processes/habits
● example:
○ stimulus: extension of day length
○ behavioral response: many bird populations tend to migrate elsewhere
○ physiological response: some animals slow their metabolism to conserve
energy
● stimulus can be communicated between organisms to trigger changes in
behavior with other organisms; they can communicate with:
○ audible signals: birds use audible signals to send warnings to other birds
or to attract mates; some primates use vocalization to assert dominance
or warn of the presence of predators
○ chemical signals (pheromones): can be released by some organisms to
illicit a response in other organisms; responses can be mating, warning
others, to scare off predators, etc.
○ electrical signals: sharks and rays can send electrical signals throughout
the water to locate prey species
○ tactile signals: touching between primates can be used to express
affection or to indicate dominance; some plants curl up to protect
sensitive parts of their bodies from damage
○ visual signals: some species use warning coloration to scare off predators
, ■ aposematism: the use of warning coloration to inform potential
predators that an animal is poisonous, venomous, or otherwise
dangerous
● signals can be used to establish hierarchy, find mates, and find resources
○ natural selection will favor signals and responses that increase survival
and the chance of successful reproduction; over time this can lead to
evolution of the population
● cooperative behaviors: can lead to increased fitness of individuals and
populations; it is cooperative if it is beneficial to another organism, the recipient,
and is selected, at least partially, due to the benefits to the recipient
○ example: meerkats take care of each other; they huddle together for
warmth, groom each other, forage together, fend off predators together in
groups, etc.
Energy Flow Through Ecosystems
● organisms use energy to reproduce, grow, and maintain organization; different
species have different adaptations for maintaining energy levels (and body
temps.)
● endotherms: use thermal energy generated from their metabolism to maintain
body temp. (ex. mammals, birds)
● ectotherms: do not have internal mechanisms for maintaining body temp.;
absorb heat from the environment; their behaviors will change depending on their
body temp. (ex. fish, reptiles, amphibians)
● metabolic rate: the total amount of energy an organism uses per unit of time
○ smaller organisms: higher metabolic rate because they have greater SA:V
ratios and lose heat more quickly; higher metabolic rates compensate for
the quicker loss of heat
○ larger organisms: lower metabolic rate because they lose heat less quickly
● net energy gain: can result in energy storage (ex. fat tissues of animals)
● net energy loss: can result in loss of mass or death of organism
● changes in energy availability can affect population sizes (less energy = smaller
population supported)
● trophic levels: represent steps in the food and energy transfers between
organisms in an ecosystem
○ organisms are classified into trophic levels based on their food and energy
sources
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