Biosc&0150:&Foundations&of&Biology&I.& & Review&10:&Chapter&42& &Adel,&Anthony,&Megan,&Dr.&Swigonova& & Page&1&of&7&Review&Chapter&42:&Water&and&electrolytes&balance&1. Aquatic&animals&and&osmoregulation:&a. Are& tissues& of& marine& fish& hypertonic& or& hypotonic& to& their&environment?&&&Hypotonic&b. What&would&happen&to&the&cells&of&a&marine&fish&if&it&did&not&osmoregulate?&&The&cells&would&shrivel&and&die&due&to&water&loss.&c. Are&tissue&cells&o f&freshwater&fish&hy pe rton ic&or&hyp oto nic&to&their&environm en t?&&Hypertonic&d. What&would&happen&to&the&cells&of&a&freshwater&fish&if&it&did&not& osmoregulate?& The& cells& would& burst& due& to& gain& of&water.&e. What&strategy&do& marine&fish&employ&to& regulate& the&osmolarity&of&their& cells?&(Explain&your&answer&in& terms&of&water/solute&intake& or&excretion.)&Does&this& process&require&expenditure&of& energy?& Marine& fish& drink& large& quantities& of& water.& However,& this& process& brings& in&excess& solutes.& Th e& solutes& are& actively& pumped& out& of& the& epithelial& tissue& of& the& gills.&Because&active&transport&is&used,&energy&expenditure&is&required.&f. What&strategy&do&freshwater&fish&employ&to&regulate&the&osmolarity&of&their&cells?&(Explain&your& answer& in& terms& of& water/solute& intake/excretion.)& Does& this& process& require&expenditure&of& energy?&Freshwater& fish&excrete& large&amounts& of&w ater& and&do& not& drink.&However,&this& process& leads&to&the& loss&of&solutes.&If& the&fish&actively&transports&ions&into&its&body& through& the& epithelial& gill& tissue,& then& energy& expenditure& is& required.& (The& fish& can&also&obtain&solutes&from&its&food.)&&2. Land&animals&and&osmoregulation:&a. List&three&ways&in&which&land&animals&may&lose&water&to&their&environment.&&Three&possible&answers& are& evaporation& from& the& outside& body,& evaporation& from& lung& tissue,& and&urination.&b. Give& one&way&in&which&an&animal&can&gain&water& without&the&physical& intake& of&liquid&water&or& food.&(Hint:& Recall&cellular&respiration.)& Metabolic&water& can& be&gained&when&oxygen&is&reduced&to&w ate r&at&the &end &of&th e&elec tron &tran spo rt&cha in.&&&3. Explain&why&aquaporins&are&never&phosphorylated&by&ATP.&Water& is& never& actively& transported,& so& aquaporins& never& need& to& be&phosphorylated.& The&active& transport&of& solutes&by&different&mem brane&proteins&is&the&driving&force&behind&water&movement.&&&4. Explain&why&insects&are&more&susceptible&to&water&loss&compared&to&other&large&organisms?&Insects&have&a& large&surface&area& to& volume& ratio&so&there&is&a&larger&area& to&lose&water& through&the&body&by&evaporation&and&a&small&volume&to&store&water&within&the&body.&a. What& advantages& to& spiracles& have& for& insects?& Spiracles& are& adaptations& for& water& loss&control&because&when&they&are&closed&they&can&limit&water&loss.&&Biosc&0150:&Foundations&of&Biology&I.& & Review&10:&Chapter&42& &Adel,&Anthony,&Megan,&Dr.&Swigonova& & Page&2&of&7&b. Suppose&you&were&able& to&manipulate& the&amount& o f&spiracles&on&an& insect.& If&you& increased&the&amount&by&a&lot,&would&this&be&an&ad van tag e&for&the&in sect? &Why&or&why&not?&Spiracles&are&advantageous&for&insects&but&increasing&the&amount&of&spiracles&by&too&much&can&pose&as&a&problem.& If&there& are&a& lot& of& spiracles,&water&loss&w hen&the&spiracles&are&open& wou ld&be&much&greater&when&there&are&many&spiracles&which&can&make&it& harder&to&regulate&water&retention.&M ore &is&not&alw a ys&be tter&in&th is&case.&&c. Suppose&there&was&an&insect&living&in&a&tropical&rain&forest&where&water&was&plentiful&and&it&was& very& humid.& W hat& m ight& the& cuticle& layer& on& this& insect& look& like?& The& cuticle& layer&would& probably&be&thinner&because& the&function& of&a&cuticle&is&to&prevent&water&loss&due&to&the&w axy & laye r& th at&makes& it& im pe rm eab le&to&wate r.& In& th e&rain&forest&water&re ten tion&would&not&be&as&much&of&an&issue&so& it& m ight& be& advantageous& to& have&a&thinner& cuticle&that&would&decrease&energy&investment.&&5. Suppose&there&was& a&solution& that&was&very& acidic.&Would&adding& am m on ia&decrease& o r&increase& the&pH& and& why?& & Acidity& is& based& on& the& number& of& dissolved&H+&in&solution&(the&more&H+&the&more&acidic)&and& N H3&is&a&base&so&it&will&gain&a&proton&and&become&NH4.& Th is &mea n s&ther e&will&be&less&H+&in&solution,&which&would&increase&the&pH,&making &the&solution&mo re&basic.&a. Why&does&too&much&ammonia&pose&as&a&problem&for&organisms?&Remember&that&enzymes&have&specific& pH&ranges&in&which&they&function&best.&Ammonia&can&alter& the&pH&of&solutions&to&the&point&that&an &en zym e &will&not&b e&ab le&to&fun ctio n&in&tha t&solu tion.&&b. List& the& different& forms& of& n itrogenous& waste& excretions& in& the& order& o f& increasing& water&retention.&W h at& is&the&trade& off&to&being& able&to&retain &w ate r?&[A m monia<Ure a< U ric& Acid]&Uric& acid& retains& the& most& water& of& all& the& forms,& however,& it& is& energy& demanding& and&requires&specia lized&e nzy m es&to &m ake .&&c. Suppose& you& find& an& organism& living& in& a& dry& desert.& Without& knowing& its& evolutionary&lineage,&what&would&you&infer& about&its& nitrogenous& waste&excretion?&It&probably &excretes&a &water&retaining&form&of&nitrogenous&waste&such&as&uric&acid&as&water&is&rare&in&the&desert.&&d. What&about&an&organism&living&in&a&deciduous&forest&where&it&does&rain?&It&wou ld &be&mo re &difficult& to&decide& without& kno w ing & its& ev olu tiona ry& line ag e& so & it& c ou ld& p rob ab ly& b e& either&ammonia&or&urea.&&e. Would&you&expect&humans&to& ever&excrete&their&nitrogenous&wastes& solely&in& the&form&of&ammonia?&Probably&not.&Humans&are&not&constantly&surrounded&b y&water&as&fish&are&and&it&requires&a&lot&of&wa ter&to &be&ab le&to &excre te&nitro ge no us&w as tes&as&a m m o nia .&&&6. Instead &of&blo o d,&what&do&insec ts &con tain&and&what&does&it&con sist&of?&Insects&pos se s s&he molymph ,&which&contains&oxygen,&nutrients,&waste,&and&electrolytes.&&a. What& is& the& function& of& an& insect’s& Malpighian& tubules& and& hindgut?& Both& are& forms& of&excretory&organs&w here&wastes&are&processed.&The&Malpighian&tubules&function&as&a&sort&of&pre& urine& creator& where& electrolytes& and& nitrogenous& wastes& are& collected& from& the&hemolymph,&which&eventually&empty,&into&the&hindgut&for&further&processing&for&excretion.&b. How& do& w astes& and& electrolytes&