Chapter 40
Study Guide and Notes
1. & 2. How has natural selection/evolution influenced
animal body SIZE and FORM?
• Physical laws – constrain what natural selection
can “invent”
– Govern strength, diffusion, movement, heat exchange
and therefore limit animal forms
Ex. Convergence of body forms in water
• Size – thicker skeletons are needed as size
increases
• Surface area:Volume – regulates size of individual
cells
– Diffusion across membranes
– Thermoregulation of body heat
How do the following organisms exchange materials with
their environment? How does their structure help this?
• Amoeba
– Entire surface is in contact
with the environment
• Hydra
– Simple organization where all
or nearly all cells are in
contact with the environment
• A flatworm
– Most cells are in direct
contact with environment
• Whale
– Extensively branched or
folded surfaces to increase
surface area
– Interstitial fluid, blood,
How are complex body plans advantageous over
simple body plans?
• Can maintain stable
internal environment
while living in a variable
external environment
– External skeleton
(protection)
– Sensory organs (obtain
detailed information)
– Internal digestion (control
release of stored energy)
– Filtration system (adjust
composition of interstitial
fluid bathing animal’s cells)
What is the difference between a
Regulator and a Conformer?
• Regulator
– Uses internal control
mechanisms to regulate
internal change in the
face of external
fluctuation.
– Mammals
• Conformer
– Its internal condition
conforms to external
changes
– Reptiles
Give an example of negative feedback in detail
What is the difference between an
endotherm and an ectotherm
• Organisms that gain
most of their heat from
metabolism (cellular
respiration)
• Mammals and birds
• Organisms that gain
most of their heat from
external sources
• Amphibians, reptiles,
many fish, most
invertebrates
List 5 adaptations for thermoregulation
• Radiation
• Evaporation heat loss
• Convection-- Movement of air or liquid past a surface
– A breeze to cool organism down
– Dilation/constriction of blood vessels
• Conduction – direct transfer
• Insulation
– Controlled seasonally
– Amount of hair, feathers, fat or raising the hair/feathers
– Oil secretions to waterproof
• Circulatory adaptations
– Dilation/construction of blood vessels
– Countercurrent exchange
• Behavioral responses
• Adjusting Metabolic heat production
– Shivering, nonshivering thermogenesis, brown fat
Explain countercurrent exchange
• The flow of adjacent fluids
in opposing directions that
maximizes transfer rates of
heat or solutes
• Blood vessels are arranged
antiparallel to one another
• As warm blood passes
through arteries, it transfers
heat to the colder boold
returning from the
extremities in the veins
• Heat exchange will occur
the entire length of the
exchanger
Basal Metabolic Rate vs. Size
Metabolic Rate per kg of body mass vs. body size