2013 HCI H2 Biology Prelims Paper 3 Questions

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© Hwa C QUESTIO Tobacco p infection le creating t Agrobacte 1.1. These protein wil step 5: R ti th step 1: Is co step 2: F p step 3: T w step 4: In tr in in step 6: T o su le tr Chong Institu ON 1 plants are eads to de a transgenic erium tumef e transgeni ll provoke a Recombinant ssue culture hen whole tra solation of onversion to c ormation o f lasmid ransformation with recombin nfection of ransformed A ntegration o f nto plant chro MV rubb e nto t h urface eaves ransgenic lt ution 2013 vulnerable ath. Scien plants th a faciens (tha ic plants c a a response f plant cells gr into plantle t ansgenic plan viral RNA cDNA f recombin a Vira for T prot n of A. tumef ant Ti plasmi plant cel A. tumefacie n f Ti plasmi d omosome ed he of of Tra B STRUCT to tobacc o tists have u at are resi s at naturally an express from the pla rown in ts and nts and ant Ti al gene coding TMV coat tein R faciens d Tr ls by ns and d DNA ansgenic plan 2 9648 H BOOKLET TURED QU o mosaic vi used genet stant to T infects plan the viral g e ants, resulti Fig. 1.1 cDN g Recombinant ransformed A t Infected p H2 Biology / J T I UESTIONS rus (TMV). ic engineer TMV. This nt cells) and ene coding ng in resista NA Le pro t Ti plasmid A. tumefaciens plant cell JC2 Prelimina It is a R N ring to over technique d the Ti pla s for TMV c o ance to TM af-specific omoter s Control T ary Examinat NA virus, w rcome this p involves t smid as sh oat protein MV. Ti plasmi carrying v for TMV protein w TMV tion / Paper 3 which upon problem by the use o f own in Fig. . The coa t RNA Coat id DNA viral gene coat within plant y f t

3 © Hwa Chong Institution 2013 9648 H2 Biology / JC2 Preliminary Examination / Paper 3 (a) Outline how the isolated viral RNA can be converted into a double-stranded cDNA in step 1. [2] (b) (i) Explain how the recombinant Ti plasmid in step 2 can be formed. [3] (ii) Explain the purpose of having a leaf-specific promoter in the recombinant Ti plasmid formed in step 2. [2] One important role of A. tumefaciens is to infect plant cells to facilitate the integration of Ti plasmid DNA into plant chromosomes in step 4. (c) Suggest another important role of A. tumefaciens in the process of creating transgenic plants which are resistant to TMV. [1]

4 © Hwa Chong Institution 2013 9648 H2 Biology / JC2 Preliminary Examination / Paper 3 Recombinant plant cells are grown using tissue culture into plantlets and then whole transgenic plants in step 5. The initial stages involve growing the plant cells in growth media supplemented with different ingredients, such as inorganic nutrients, before a change of environment is required for the newly formed plantlets in the final stage. (d) (i) Describe the functions of two other named ingredients in the growth media in the development of plant tissues. [4] (ii) Explain the significance of the change of env ironment for the newly formed plantlets in the final stage of tissue culture. [2] [Total: 14]

5 © Hwa Chong Institution 2013 9648 H2 Biology / JC2 Preliminary Examination / Paper 3 NAME: __________________________________ CT GROUP: 12S7 ___ BOOKLET II STRUCTURED QUESTIONS (continued) BLANK PAGE

© Hwa C QUESTIO A couple’s fertilisation conductan (a) Stat The CFTR 2.1 shows (b) Usi n (i) Chong Institu ON 2 s first child n, they u n nce regulato e what is m R alleles of s the results ng the inform the three- ution 2013 is affected nderwent g or (CFTR) a meant by gen each family s of gel elec mation give -day-old em by cystic fib genetic te s allele in thre netic testing y member a ctrophoresis n in Fig. 2.1 mbryo will de 6 9648 H brosis. As sting for t h ee-day-old e g. are amplifie s performed Fig. 2.1 1, explain w evelop into H2 Biology / J they are try he mutant embryos. d by polym d on each D why a child affe JC2 Prelimina ying for a s cystic fib r erase chain NA sample cted by cys ary Examinat econd child rosis tran s n reaction ( e. stic fibrosis. tion / Paper 3 d by in vitro smembrane [1] PCR). Fig. [2] o e

© Hwa C (ii) The coupl CFTR alle (c) Sug Chong Institu the posit i comparis le’s first ch eles being tr gest why th ution 2013 ion of allel on with alle ild undergo ransferred i he child can e 2 on th e ele 1. oes liposom nto his trac not pass on 7 9648 H e agarose me-mediated cheal epithe Fig. 2.2 n the norma H2 Biology / J gel indicat e d gene the r lial cells. al CFTR alle JC2 Prelimina es that it c rapy. Fig. 2 ele to his of ary Examinat contains a 2.2 shows ffspring. tion / Paper 3 deletion in [2] the normal [1]

© Hwa C (d) Stat this limit impr Linkage a human c h markers. mutation. (e) Des 7. Chong Institu e one limit limitation. [2] ation: rovement: analysis usin hromosome The aste r cribe how R ution 2013 ation of lip o ng RFLP m e 7. Fig. 2 rix (*) indic RFLP analy osome-med markers prov 2.3 shows ates the p o ysis facilitate 8 9648 H diated gen e vided evide the positi o osition of a Fig. 2.3 ed linkage m H2 Biology / J e therapy a ence for th e on of the C a Taq I re s mapping of JC2 Prelimina and sugges t existence CFTR locu s striction sit e the CFTR ary Examinat t one impr o of the CFT s in relatio e that can gene on ch tion / Paper 3 ovement t o TR locus on n to RFL P be lost b y hromosome [4] o P y e

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