LIFE SCIENCES: PAPER I

Transcription

1 NTIONL SENIOR ERTIFITE EXMINTION EXEMPLR 2008 LIFE SIENES: PPER I EXMINTION NUMER THERE RE 7 PGES IN THIS OOKLET QUESTION 1 swer the questios i the spaces provided. Place this booklet iside the swer ook i which you aswer the rest of the examiatio paper. 1.1 Observe this photograph of chromosomes ad use this to select the term i the right colum which best matches the descriptio i the left colum. Write the letter of the term i the correspodig space provided betwee the brackets. Use each letter oly oce. [dapted from Ket] escriptio Term [ ] hromosomes ca be see i the detail show here with the RN microscope. [ ] hromosomes i this state have udergoe the process of chromatids [ ] The most importat chemical compoet of chromosomes is electro [ ] These chromosomes cosists of two N [ ] The two parts of the chromosomes are joied by E light F cetromeres G traslatio H replicatio (5) PLESE TURN OVER

2 NTIONL SENIOR ERTIFITE EXEMPLR: LIFE SIENES: PPER I Page 2 of Five multiple choice questios are give below. hoose the most correct optio for each questio ad write the correspodig letter of that optio i the space provided i the table below. Questio swer (5) For questios ad refer to the followig iformatio about hyperdactyly, a geetically iherited coditio. I humas the coditio of hyperdactyly (the possessio of twelve figers) is determied by the domiat allele (H) ad the ormal coditio by the recessive allele (h). The followig diagram shows a family tree i which some members of the family are hyperdactylous = hyperdactylous male = ormal male = hyperdactylous female = ormal female [dapted from Torrace] Paret 1's geotype is heterozygous homozygous recessive homozygous domiat lackig the mutat gee The geotypes of persos 1, 2 ad 3 i this family tree are HH Hh hh HH HH hh Hh HH Hh Hh Hh hh

3 NTIONL SENIOR ERTIFITE EXEMPLR: LIFE SIENES: PPER I Page 3 of ad refer to the followig iformatio. quee hoey bee ca lay both fertilised ad ufertilised eggs. Fertilised eggs develop directly ito diploid females ad ufertilised eggs develop directly ito haploid males. The diagram shows the formatio of gametes i male ad female bees. cell of adult female bee 2 cell of adult male bee cell divisio female gametes male gametes The type of cell divisio that forms male gametes i the hoey bee is meiosis. mitosis. a reductio divisio. the same as occurs i huma males I the formatio of female hoey bee gametes, variatio is caused by crossig over. N replicatio. trascriptio. fertilisatio. PLESE TURN OVER

4 NTIONL SENIOR ERTIFITE EXEMPLR: LIFE SIENES: PPER I Page 4 of The X hromosomes of fruit flies (rosophila melaogaster) sometimes show a lethal (deadly) mutatio. The graph below shows the results of a ivestigatio to fid out the effect of icreasig X-ray radiatio o the percetage umber of X chromosomes displayig the mutatio. % umber of X chromosomes showig lethal mutatio dosage of x-rays (roetges) [dapted from Torrace] The dosage of x-rays has the followig relatioship to the % of lethal mutatios: Iversely proportioal expoetial icrease irectly proportioal No patter of relatioship 1.3 Fill i a tick o this table to show where the structural compoet listed i the first colum is preset, i N, mrn ad/ or trn. Nucleic acids Structural compoet N mrn trn eoxyribose sugar Guaie, cytosie, adeie Thymie Uracil Phosphate Ribose sugar (6)

5 NTIONL SENIOR ERTIFITE EXEMPLR: LIFE SIENES: PPER I Page 5 of The followig graph illustrates the chromosome complemet (umber) of a cell durig meiosis. N cotet of cell Time [dapted from Pickerig] Use the letters R, P, M, G ad label o the graph: R where N replicatio takes place. P where homologous pairig occurs. M where double straded chromosomes alig themselves i a double row at the equator. G where the cells are haploid. (4) raw a diagram of a sigle pair of homologous chromosomes showig the process of crossig over. Label ay 2 structures. o ot draw ay other cell structures. (5) PLESE TURN OVER

6 NTIONL SENIOR ERTIFITE EXEMPLR: LIFE SIENES: PPER I Page 6 of The data below resulted from a study coducted i the US. Use the data ad your kowledge of Life Scieces to aswer the questios that follow. Method of cotraceptio Male sterilisatio Female sterilisatio Hormoe implat Ijectable hormoes Itra-uterie device The pill The mii-pill odoms diaphragm Vagial spermicides Periodic abstiece Vagial spoge Effectiveess of method (pregacies/ 1000 users/ year) [Source: The Ecoomist] Give a headig for the table. (2) What was the idepedet variable i this study? (1) What type of graph would you draw to make the results easier to read? Give a reaso for your aswer. (3) Suggest two other variables (factors) that should have bee take ito cosideratio i this study to improve its accuracy. Provide a reaso for each of your suggestios. (4)

7 NTIONL SENIOR ERTIFITE EXEMPLR: LIFE SIENES: PPER I Page 7 of Which was the least effective method of cotraceptio? hoose oe of the most successful methods of cotraceptio ad explai why you thik it was effective. (1) odoms are ot rated as very effective i this study, yet their use is beig promoted by the epartmet of Health i South frica. Why? (2) (2) 40 marks