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 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

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