23 Evolution Exercises

-~ __ _ , .Ji/8 /i,liJte5 snd ftercises In~ - ~- ~~ ,-- - fXEROSE - f\'OJ.lf!'lOl'i . d E nvironm e nt slc'E -- Sc••"""· TL-rhnoloM • sor1 etv an NOS ::::-: Nature of Science SI S c! ellt111C lr'IQUII'\ ' I , "s t ions that follow: I. Rr,d 1IK 1 ,;i »a :: ,· 1,ci<" ' and : 11is"cr 11 c qu e- · "-=- 188 ,----- . f . 0 , ·s rn that lived thou sa nd s or millions f h "s il is 1h e ma rk or rem ai ns o an ° 1 od 11I 0 yea rs a ~ · - k I t that were pre ser ved after a pl an t . · 'go_ . . • ed ~, rnie tossi ls are l eaves . she ll s, ors e e ons or an 1m al d' Othe rs are tr ac ks or trai ls l eft by rnovmg anirnals. · · The fossi ls pre serve d in the s trata of the Grand Canyon in Arizona provide a good _ _ _ . . exam 1 of the mcreasmg com plexity of Itvmg things. Strata near the bottom contain only . . p e f · pnm1ti v ossrl algae . Strala higher up contain fossils of invertebrates. Above which . e fi . . , rem am s sh b eg m to appear. Some of the upper strata contain tracks of such early la d . of h . . n ammal a mp ,brans and small reptiles . s as ( a) ( i) Whole plant and animal fossils are very rare. Give a possible reason for this (1 m k · ar ! (ii) Based on your answer in (i), suggest how an entire animal fossil may be preserved naturally. (2 mark s) . d'fferent (b) The pa ssage above has mentioned a number of animals whose fossils are fou nd m I t 10 flowchar s trata of the Grand Canyon. Based on the information provided, construct a ·k s) . . . ' (2 ,na, s how the pos s ible evolul!onary relattonsh1ps among these animals.

, . 1 , relative positions of the fo sn . ) 1 ic I s in the s tr at ( t' se 0 rga ni sms. However, th e act , 1 . · c a c an o nl y tell th e o rd er of oc curren ce of tlio . ..., l uc1 t1n 1 cs \V I 17 ae st h ow th e age of a particuj ,, . 1 .- , ,· ' icn Such oq.w , 1i 1, n1 1, ap rcarcd arc n ot kn ow n. S ll .:-c «t n ss i1 can h r . Exercise - EVi c uund sc 1cntifiu tlly. (2 marks) Total: 7 marh , ~a ny evo lutioni st s put forwa rd various hypothe ses to ex pl a in th e origin of th e long n eck of •· ,n odem g iraffes. The diagram below shows one of the se po s tulated m ode ls: Orginally giraffes had short necks. However, occasionally some long-necked giraffes appeared in the population . • k d giraffes could reach the higher leaves on the Theselong-nec e . trees in times of drought and surv1ed better. J """,,. .. <,,i~~-~-- ,,;,,,,Ji#-,;a; • ,,. , ,;,q, . ,_ __ , _ - . ff ·n the population had long After many generations, all g1ra es , necks. 189 ~ .-•

he passage be low and answer th e . vl,id t questions th,1t , . 11 _\, I' t () 0\V : Exercise - Evofution " first antibiotic, penicillin, Was ct· ,, -- -- flw lscovcrc I . ll · used to treat ba t .·, . . l 111 19 29 hy J\ I . , . . genera Y . . c eital tlll'ections , cs , ,· . CX t11td n l· lc 1 11 111 g. 11 was t hen " cc i l111tially th e , ·1 · . · P ct: 1 i1ll y lh u "l' .. . 1 . '(reptoco · ' <lnt101ot1c Was , 1 . 1 . ,. . l dli '-l t hy , 111;1!1 \' / r,r ·n('('t and • 1 . H c Cc t1 vl' , 1 . , · these bactena. owever, r es istan ,_ . . . cg i1111 s1 , ill so r1 1, nl inlcc 11 , ,n 1, c, ,u ,;;c d b )' . . ce to Pen1c1llin in S () , _ . . oanised shortly after introduction f h · rn c s 11 ; 11n s ol ,1r, 1 ,1 /\ ,f fir (J('( i wa 1., re c i, . · 0 t e drug . Toda ., .·. . . . Y as 80% of all strams of Sta1Jhvl .. y, t es is tan cc to r cn1c 1l lin <K cllr .., in a -., man ,- . Otocc r, s aureu .,·. Many chemicals can also kill bacteria ff . (a) • . e eclJvely. But why are antibioti cs pa rti cu larly important m chemotherapy? ( / mar k) (b) In a bacterial population, some cells have greater resistance to the antibiotic than the r es t. Explain two genetic causes that may lead to this variation among the bacteri al eel l s. (4 mark s)

. - NS S B io lo gy -Intensive Notes and Exercises (c) Using the theory of natural selec tion, explain swp hylococci have become resista nt to penicillin. why incr easing number of str a· in s of (4 rnark s) ------------ --- Total: 9 marks 4. Sedimentary rocks are laid down in layers called strata. Fossils contained in successive rock s trat a can provide evidence for evolution. (a) What evidence can be obtained from the study of such fossils for the hypothesis of divergent evolution? ( 3 marks ) (b) Based on fossils di sc overed in North America in the 1870s, a sequence of species believed to have evolved gradually from Hyracotherium into the modern horse in a "straight-line" has beeil . ·t d from con s tructed. The diagram on p.193 shows the sequence of evolution of horse reconstruc e fossils obtained from successive rock strata.

, 5 d their diet f rom I·ruit , d Exercise . d ch3n ge < .tr1<1 \ . , Notes an ' , im als h,, . h' d caused corr es ponding ·h 11 1\ l - tntenst\ e . th e cl ll . r d , et cl . . c.: a~ I . NSS gioJOgy' )ro pn sc 1\1 ,,t ·1 , ,n ae in th ct_ h ·r rn o\ars which mig ht h ave <le. \· ~t· . . ts a\ sC) I 1~ 1i e L ,, ~ . in t et <lilt \• scient , :-- . ,-,, sses- · 11 L - 1i ~ 111 g cs (2 .(\ ( ii ) ' 1 \I 11 ' • 1 C , rn_ I . \ ia l: l. ' lll 1n t1 ).l. i::- • \ fll'O po ss \ llr k ,J 0 • s· u 0ULS · 1 -c th. · r:- ~ . \ \1 ' 1 \ l ,n l -1·1 -t ch: 111 ~ -· . \ he ' \ t\1 (' 11 111 ·, ----- 5. Thi." evo\utic m ary tr ees h ow n below clas ------ ----- · s A to E. sifies five specie A --- ---- -- - --- -- - Total: 8 mar ki B common ____ --,.. ancestor C E ( a) Wh ich pa ir of s pecies are the most closely related? Give a reason for your answer. (2 mark s! (/J ) All th ese rive sp ec i es belona to t\ , . . ut in . .. b 1e s, une tanuly Wh . . . . h to be P d 11l cre nt o rd e rs'! ' · Y 1s it 1mposs1ble for t em -~) ( 1 11101 --- ~ : 194

. rckism is an evolutionary theor Exercise - Evolution ~ il111,1 y proposed I 0 , r ·k dev eloped two laws to exph. ' )Y th e Fr ench l . 1 . 1 , 1111 8 c ' 111 evolution Th 1 10 og 1st Lamarck in 1809. , --------- . ey ar c cl csc ·1 J . . ~ -- · fl 1 cc as tollo ws: Use or disuse causes structure , t , --- - __ J. s o enlar ge ()1· l•I . k - - ·' 11'111 J[. All acquired changes were heritable . · ---- In an experiment conducted b W . - - - - - ( a) . Y eisinann the t· ·1 · • successive generations. It was found ti. . ' · < II s of mi ce we re c ul r,lf o ve r m,rn y - . lctt th ere was .· ·. ·· , . . . the progeny . Explam how these findino . . no sig nifi c ant ch an ge 111 1hc tail .., ,;c 1Jf bs cont1ad1ct Larnarcki s rn . U rw1rk ,J ( b) How can the knowledge of genetics help refine Darwin's theory of evolution? (3 marks) . h d led to formation of new species. Explain why. ( c) Domestication of ammals by humans a (4 mark s) Total: 10 marks 195