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 formsEx. 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
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