Bio 320 Exam 2 Study Guide Solutions

BIO 320 EXAM 2 STUDY GUIDE SOLUTIONS Describe all processes by which organisms exchange heat with their environment. - ANSWER- Radiation, Conduction, Convection, Evaporation Radiation - ANSWER-*Emission of electromagnetic energy by surface (i.e. sun) *When objects are warmed by radiation, they emit lower-energy radiation as infrared light *The temp of the radiating surface determines how rapidly an object loses energy by radiation to colder parts of the environment. Conduction - ANSWER-*Transfer of kinetic energy of heat between substances in contact (i.e. lizards lying flat on rocks to warm) *Rate of heat movement depends on 1) surface area 2) resistance to heat transfer 3) temp difference *Greater surface area=greater surface for energy transfer (i.e. animals curling up in ball for warmth) Convection - ANSWER-*Transfer of heat by movement of liquids and gases (Molecules of air or water next to warm surface gain energy and move away from surface)*When environment is cold, organism ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 2/12 warms it's boundary layer which reduces heat loss but current of air can disrupt layer and carry away heat by convection (wind chill) Evaporation - ANSWER-*Transformation of water from liquid to gas using heat energy *Removes heat=cooling effect on organism *Plants transpire/Animals breathing makes water evaporate from exposed gas exchange surfaces esp. in higher temp. Homeotherms - ANSWER-Maintain constant temperature conditions within the cells. Poikilotherms - ANSWER-Does not have constant body temperatures. Ectotherms - ANSWER-*Body temp largely determined by external environment *Usually have low metabolic rates (reptiles, amphibians, plants, insects- those that cant generate or retain heat to offset heat loss)*Ectotherms adjust temp by altering behavior (moving in/out of shade, etc) Endotherms - ANSWER-*Generate enough metabolic heat to raise body temp higher than external environment *Most mammals/birds maintain body temp between 36°C-41°C, despite surrounding temp. *Maintaining a higher body temp gives them more energy for activity like find food and escape. ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 3/12 *Sustaining internal conditions despite external difference requires a lot of work/energy *Organisms make up for temp difference by generating metabolic heat or gaining through radiation, conduction, or convection. Radiation Equation - ANSWER-AεT^4 σ *A=surface area of obj emitting radiation *ε=defines how effectively obj radiates energy (0-1) *T=temp of obj expressed in K *σ=Boltzmann constant *^Temp=exponential inc in radiation *Organism emits radiation to and received radiation from environment. Hot organism in cold environment will emit more than it gains, meaning radiation will cause body to cool. *Organism w/ temp that equal environment will emit as much as it receives, canceling change. Conduction Equation - ANSWER-(KA(Tb-Tg))/L *Tb= temp of body surface *Tg=temp of ground (or other solid) ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 4/12 *A=area of contact between organism & environment *k=conductivity (how well solid conducts heat) *Tb equals the temperature of the body surface *Tg equals the temperature of the ground (or another solid). *L=distance of heat transfer *Surfaces like metals have high conductivity, meaning they transfer heat rapidly. Insulation such as fur or feathers will increase the distance that heat must flux between an organism and its environment Convection Equation - ANSWER-hA(T_b-T_a) *Tb=temp of body surface *Ta=temp of air/water *A=surface area in contact with fluid *h=convection coefficient (shape of organism and movement of fluid that determines rate of heat flux by convenction) *larger h means larger heat flux Evaporation Equation - ANSWER-cA(e_w-e_a) ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 5/12 *eW=vapor pressure of water in body *eA=vapor pressure in the air *A=surface area where water can evaporate *c= constant that converts water loss to heat loss *Evaporation requires water concentration of the body to exceed that of air. When the air has less water than the body, the pressure generated in body exceeds that of water in the air so water molecules push their way into air as vapor. Freshwater Osmoregulation - ANSWER-*Freshwater animals have higher solute conc in their tissues than surrounding water. *Freshwater fish continuously gain water when they consuming food and osmosis occurs across mouth and gills (most permeable tissues exposed to water) *Fish respond to this influx of water by eliminating the excess water through urine *They add solutes to their bloodstream by using their gill cells to actively transport solutes into the body from water, and use kidney to remove ions from their urine Saltwater Osmoregulation - ANSWER-*Hyposmotic organisms must a