 Use free energy to maintain homeostasis in response
to environmental conditions
 In order to survive, organisms need:
Timing and Coordination
 Diversity of life on Earth
 6 kingdoms
 Organisms detect environment conditions
 Organisms communicate
 Endocrine, Immune, Nervous System
 Animal behaviors
Maintaining homeostasis
 Negative feedback:
returning the changing
condition back to its
target set point
 Ex: temperature
regulation in animals
 Ex: plant responses to
water limitations
 Positive feedback:
amplification of a
response by moving away
from its set point.
 Ex:ripening of fruit
 Ex: labor in childbirth
 Leads to harmful effects on individual
 Ex: diabetes
Respond to a changing environment by using energy to
maintain homeostasis
 Organisms respond to changes in their environment
through behavioral and physiological mechanisms
 Excretory system in flatworms earthworms and
vertebrates
 Osmoregulation in bacteria fish and protists
 Osmoregulation in aquatic and terrestrial plants
 Thermoregulation in aquatic and terrestrial animals
Using energy to respond to the environment to maintain
homeostasis
 Directed movement in response to stimulus
 toward attractant: food
 away deterent: poison
 Structure: flagellum
 Bacteria expel proteins in normal lifecycle
 Populations increase other functions begin
 When environment lacks specific nutrients, bacterial
cell develops protective cell
 Genome is copied
 Water is removed
 Metabolism stops
 Original cell lysis
 Endospore endures
 Dormant for centuries
Using energy to respond to the environment to maintain
homeostasis
 Occur as a result of internal and external signals that
synchronize with environmental cycles and cues
 Ex: fruiting body development in response to nutritional
depletion
Using energy to respond to the environment to maintain
homeostasis
 Growth in response to light
 (positive) toward light shoots
 (negative) roots down
 Mechanism: auxin hormone
 Response to timing of light
 Determine time of day/season
 Mechanism: phytochrome
 Positive feedback mechanism
 Mechanism: Ethylene
 Plants pass materials between cells
 Physical defense:
 Thorns, trichomes (hairs)
 Chemical defense:
 Glycosides – anti-herbivory
compound
 Symbiotic defense:
 Recruitment of animals –
ex: acacia tree and ants
 Flower development
 https://vimeo.com/75555419
 C4 plants – alternate
way to fix and store
CO2 to avoid water
loss
 CAM plants – close
stomata in day to
conserve water, open
at night for gas
exchange
Using energy to respond to the environment to maintain
homeostasis
Contact (Plant Cells)
Short Distance
Contact (Animal Cells)
Long Distance
 Hormones (Endocrine System)
 Antigens (Immune System)
 Neurotransmitters (Nervous System)
 http://www.dnatube.com/video/1113/The-Endocrine-
System-How-it-Functions
 Molecules produced by endocrine cells
 Typically travel through circulatory system
 Medicine:
 Birth control
 Depression
 Blood pressure
 Metabolism
 https://www.youtube.com/watch?v=zQGOcOUBi6s
 Recognize and quickly fight pathogens
 1st line – barriers (skin, mucous membranes)
 2nd line – internal, non-specific defenses (general
responses against any invader that gets through)
 Organism Barrier: Chitinous exoskeleton
 Cellular: Hemocytes ingest bacteria
 Molecular: Lysozyme enzymes break cell walls
 Organism Barrier: Skin
 Cellular: Neutrophils and macrophages
 Molecular: Interferon & 30 protein complement
system
 Histamine and cytokine signals trigger capillaries to
dilate
 Vertebrate defenses
remembered after
initial exposures
 Humoral – B-cells
produce
antibodies to
attack pathogen
 Cellular – T-cells
attack pathogen
 https://www.youtube.com/watch?v=z3M0vU3Dv8E
 https://www.youtube.com/watch?v=x4PPZCLnVkA
 http://highered.mheducation.com/sites/0072495855/s
tudent_view0/chapter14/animation__the_nerve_impu
lse.html
Nervous system receives signals, brain regulates behaviors to
respond to them
 Response of a muscle or gland under control of the
nervous system in response to a stimulus
 Innate vs. Learned
 Kinesis
 Random movement in response to stimulus
 Ex: Paramecium slow down and turn more often in the
presence of bacteria (food)
 Taxis
 Direct movement toward/away from stimulus
 Ex: American Cockroach hides from light
 Detection of light to set internal clock
 Mechanism: pineal gland detecting sunlight
 Regular long distance change in location
 Mechanism (in birds)
 Magnetite in brain to visualize magnetic field
 Lowering of metabolism to survive seasons
 Honeybees perform the waggle dance to communicate
the location of food sources
 Pheromones
 Ex: alarm or reproductive
 Pack behavior in animals
 A loss of responsiveness to stimuli that convey little or
no new information
 Ex: prairie dog alarm call in human presence
 Ability to associate one environmental feature with
another
 Ex: Mouse associates color/taste
 The process of recognizing and following the first
moving object encountered during a “sensitive period”
of life (learned/innate)
 Scientists often wear costumes to prevent human
imprinting with endangered species
 The process of knowing by awareness, reasoning,
recollection & judgment.
 Ex: primates learn how to use tools