
	Trending ▼ ICSE CBSE 10th ISC CBSE 12th CTET GATE UGC NET Vestibulares ResFinder

GCE MAY 2006 : (A2 2) Reproduction, Genetics and Taxonomic Diver

24 pages, 41 questions, 0 questions with responses, 0 total responses,

	gce	+Fave Message
	Profile Timeline Uploads Q & A

Home > gce >

Formatting page ...

Centre Number 71 Candidate Number ADVANCED General Certificate of Education 2006 Biology assessing Module 5: Reproduction, Genetics and Taxonomic Diversity A2B21 Assessment Unit A2 2 [A2B21] THURSDAY 25 MAY, MORNING TIME 1 hour 30 minutes. INSTRUCTIONS TO CANDIDATES Write your Centre Number and Candidate Number in the spaces provided at the top of this page. Write your answers in the spaces provided in this question paper. Answer all nine questions. For Examiner s use only Question Number 1 INFORMATION FOR CANDIDATES The total mark for this paper is 75. Section A carries 60 marks. Section B carries 15 marks. You should spend approximately 20 minutes on Section B. You are expected to answer Section B in continuous prose. Quality of written communication will be assessed in Section B. Figures in brackets printed down the right-hand side of pages indicate the marks awarded to each question or part question. 2 3 4 5 6 7 8 9 Total Marks A2B2S6 1628 Marks BLANK PAGE A2B2S6 1628 2 [Turn over Section A Examiner Only Marks 1 Remark Complete the key below to identify the four different phyla of the kingdom Animalia labelled A, B, C and D. Is the animal triploblastic? Yes No Phylum A _____________________ Does the animal have a body cavity or coelom? Yes No Phylum B _____________________ Does the animal have an internal skeleton composed of bone or cartilage? Yes No Phylum C _____________________ Phylum D _____________________ [4] A2B2S6 1628 3 [Turn over 2 The diagram below represents the structure of a prothallus. Examiner Only Marks Remark archegonia antheridia rhizoids Source: A-Level Biology (Revised edition), W. D. Phillips and I. J. Chilton, Oxford University Press, 1995 (a) (i) In the life cycle of which type of plant is the prothallus found? ___________________________________________________ [1] (ii) What is the ploidy of the prothallus? ___________________________________________________ [1] (iii) The prothallus is normally found in damp conditions. Suggest one reason for this. ______________________________________________________ ___________________________________________________ [1] (b) (i) The antheridia and archegonia illustrated in the diagram produce gametes. What type of gamete is produced in the antheridia? ___________________________________________________ [1] (ii) State one difference between the gametes produced by the antheridia and archegonia. ______________________________________________________ ___________________________________________________ [1] (c) Suggest one possible function of the rhizoids illustrated in the diagram above. _________________________________________________________ _______________________________________________________ [1] A2B2S6 1628 4 [Turn over 3 The diagram below shows hyphae of the pin-mould fungus, Mucor. Mucor is an early coloniser of the fresh dung of herbivores, such as rabbits. vacuole Examiner Only Marks Remark cell wall dung cytoplasm Source: Adapted from C. J. Clegg Microbes in Action , John Murray, 2002 (a) State the composition of the cell wall of Mucor. _______________________________________________________ [1] (b) Describe how Mucor obtains food. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] Organisms of the kingdom Fungi are eukaryotic. (c) Give one feature of eukaryotic organisms. _______________________________________________________ [1] (d) List the three other kingdoms in which eukaryotic organisms are found. 1. __________________________ 2. __________________________ 3. __________________________ A2B2S6 1628 [2] 5 [Turn over 4 A saddle pattern of the wool of a sheep is due to a recessive allele at a single gene locus. In a flock of sheep 800 lambs are produced of which 4% show the saddle pattern. The saddle pattern within the population of lambs is considered to be in Hardy Weinberg equilibrium. Examiner Only Marks Remark (a) (i) Calculate the relative frequency of the saddle allele and the non-saddle allele in the population of lambs. (Show your working in the space below.) Relative frequency of saddle allele __________________ [2] Relative frequency of non-saddle allele __________________ [2] (ii) Calculate the relative frequency of lambs which might be expected to be homozygous non-saddle and heterozygous non-saddle . (Show your working in the space below.) Relative frequency of homozygous non-saddle lambs __________________ [2] Relative frequency of heterozygous non-saddle lambs __________________ [2] (iii) Calculate how many of the 800 lambs would be expected to be heterozygous for the non-saddle pattern condition. (Show your working in the space below.) Number of lambs heterozygous for the non-saddle condition __________________ [1] A2B2S6 1628 6 [Turn over Since the saddle pattern reduces the value of the wool, the farmer selects the unwanted lambs and sells them for slaughter. In the next generation 2.8% of the lambs have the saddle pattern in their wool. He continues to select for another five generations and the incidence of the saddle pattern is reduced to 1%. Examiner Only Marks Remark (b) Explain why the saddle pattern is still reappearing after five generations of selection against it. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] A2B2S6 1628 7 [Turn over 5 (a) A couple who are not otherwise able to have children may undertake a programme of treaments involving in vitro fertilisation (IVF). The diagram below outlines stages associated with IVF, following the initial hormone treatment of the woman. During an operation eggs are removed by a syringe. Examiner Only Marks Remark Sample of semen is produced by male. Sperm and eggs are mixed in a suitable culture medium. Fertilised eggs remain in culture medium for several days. Two or three early embryos inserted into uterus through the vagina. Remaining embryos frozen and stored. liquid nitrogen Source: Bradfield, Dodds, Dodds and Taylor AS Level Biology , Pearson Education, 2001 (i) Suggest one infertility problem for which IVF is a suitable treatment. ______________________________________________________ ___________________________________________________ [1] (ii) Suggest why the woman receives hormone treatment at the commencement of the IVF programme. ______________________________________________________ ___________________________________________________ [1] (iii) Suggest one reason why the fertilised egg is cultured for several days before being implanted in the uterus. ______________________________________________________ ___________________________________________________ [1] A2B2S6 1628 8 [Turn over (iv) Suggest one problem that may arise from implanting more than two or three embryos into the uterus. Examiner Only Marks Remark ______________________________________________________ ___________________________________________________ [1] (v) Suggest what course of action is available to the couple if, still wishing to have a child, this initial treatment is unsuccessful. ______________________________________________________ ___________________________________________________ [1] (b) Culture media, in which eggs may be fertilised in vitro and in which embryos may subsequently develop, contain human serum albumin. Albumin is a blood protein which is used as a stabiliser to create an optimal growth environment. Until recently albumin was obtained from blood donors. Now, recombinant human albumin, produced from genetically engineered yeast (Saccharomyces cerevisiae), is used and this is regarded as a safer option. (i) Suggest one way in which albumin may act to stabilise the environment of the eggs or embryos. ______________________________________________________ ___________________________________________________ [1] (ii) Suggest why the use of recombinant human albumin is considered to be safer than using albumin obtained from blood donors. ______________________________________________________ ___________________________________________________ [1] (iii) Suggest how the human gene for albumin might have been incorporated into yeast cells. ______________________________________________________ ___________________________________________________ [1] A2B2S6 1628 9 [Turn over 6 A species of cichlid fish, Tilapia nilotica, is found in Lake Turkana in Kenya. Examiner Only Marks Remark (a) The table below shows the classification of Tilapia nilotica. Complete the table by inserting the names of the three missing taxonomic groups. Kingdom Animalia Chordata Class Osteichthyes Perciformes Family Cichlidae Tilapia Species nilotica [3] Over the last 10 000 years the water level in the lake has fluctuated considerably. A volcanic island in the lake has a crater which filled up with water and fish when the water level was high. Later it became isolated as the water level fell. Tilapia nilotica is found in the main lake but a different species, Tilapia vulcani, is found in the crater within the island. The two species are very similar in appearance which suggests a common ancestor. The diagram below shows a map of the island and the flooded crater containing T. vulcani. Tilapia nilotica Tilapia vulcani Lake Turkana Source: Bradfield, Dodds, Dodds and Taylor A2 Level Biology , Pearson Education, 2002 A2B2S6 1628 10 [Turn over (b) Suggest an explanation of how the species known as Tilapia vulcani might have arisen. Examiner Only Marks Remark _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [4] A2B2S6 1628 11 [Turn over 7 In cats, a pair of sex-linked alleles G and g may determine coat colour. Ginger is controlled by the allele G (designated XG ) while black is controlled by the allele g (Xg). In the heterozygous condition female cats are described as tortoiseshell (a mixture of ginger and black fur). Examiner Only Marks Remark (a) Explain why there are no tortoiseshell male cats. _______________________________________________________ [1] The effect of the G and g alleles is modified by the alleles at another locus, known as the dilution gene (which is not sex-linked). The dominant allele D ensures that the alleles G and g are expressed at their full colour intensity. The recessive allele d changes the ginger colour to cream and the black colour to grey, while the heterozygote becomes a pale tortoiseshell. (b) State the phenotype and gender of the genotype ddXgXg. _______________________________________________________ [1] (c) Two cats of the following genotypes were crossed. DdXGXg DdXgY Determine the expected proportions of the offspring produced in terms of colour and gender. Show your working in a genetic diagram in the following space. A2B2S6 1628 12 [Turn over Examiner Only Marks Remark [6] (d) Using the example above of coat colour in cats, distinguish between allele interaction and gene interaction. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] A2B2S6 1628 13 [Turn over BLANK PAGE A2B2S6 1628 14 [Turn over 8 Triploid rainbow trout (Oncorhynchus mykiss) may be produced by fertilising eggs in which the meiotic cycle is inhibited by heat- or pressureshock. A diploid egg nucleus, then combining with a haploid sperm nucleus, produces a triploid zygote. Examiner Only Marks Remark (a) The diagram below shows the appearance of a red blood cell from a diploid and a triploid fish. The cells are nucleated. Triploid Diploid 10 m (i) State one way in which the red blood cell of the fish differs from that of a mammal. ___________________________________________________ [1] (ii) Explain why the red blood cell nucleus of a triploid fish is bigger than that of a diploid fish. ______________________________________________________ ___________________________________________________ [1] (b) Triploid organisms cannot produce gametes and so are sterile. Explain why triploid organisms cannot produce gametes. _________________________________________________________ _______________________________________________________ [1] A2B2S6 1628 15 [Turn over The growth of diploid female rainbow trout and triploid female rainbow trout in a reservoir, over an approximate 4-year period, is shown in the graph below. 2000 triploid Mean mass/g 1600 1200 diploid 800 400 0 0 12 24 36 48 Age of female trout/months Examiner Only Marks Remark (c) Describe the trends shown in the graph. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] A2B2S6 1628 16 [Turn over All triploid fish are sterile and female triploids exhibit restricted ovary development so that eggs are not produced. Another relevant feature is that triploids are generally less aggressive (e.g. in their feeding) than diploids. Diploid trout, in this reservoir, become sexually mature in their third year. Female diploids produce hundreds of eggs. Examiner Only Marks Remark (d) Use the information above to suggest explanations for the trends identified in the graph. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] The same number of diploid and triploid females were introduced into the reservoir (where angling was permitted). At the end of four years fish were caught by netting and within the sample of fish caught the number of diploids and triploids differed. The ratio of triploids to diploids was found to be approximately 2 : 1. (e) Suggest two possible reasons for the difference observed. (Use any of the information offered previously to answer the question.) 1. _______________________________________________________ _________________________________________________________ _________________________________________________________ 2. _______________________________________________________ _________________________________________________________ _______________________________________________________ [2] A2B2S6 1628 17 [Turn over Section B Examiner Only Marks Remark In this section you are expected to answer in continuous prose, supported, where appropriate, by diagrams. You are reminded that up to two marks in this question are awarded for the quality of written communication. [2] 9 Give an account of meiosis, and explain its importance within life cycles and its role in promoting genetic variation. [13] _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ A2B2S6 1628 18 [Turn over Examiner Only _____________________________________________________________ Marks Remark _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ A2B2S6 1628 19 [Turn over Examiner Only _____________________________________________________________ Marks Remark _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ A2B2S6 1628 20 [Turn over Examiner Only _____________________________________________________________ Marks Remark _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ A2B2S6 1628 21 [Turn over Examiner Only _____________________________________________________________ Marks Remark _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ A2B2S6 1628 22 [Turn over THIS IS THE END OF THE QUESTION PAPER A2B2S6 1628 23 [Turn over Permission to reproduce all copyright material has been applied for. In some cases, efforts to contact copyright holders may have been unsuccessful and CCEA will be happy to rectify any omissions of acknowledgement in future if notified. S 6/05 4500 302507(72)S

Formatting page ...

Additional Info : Gce Biology May 2006 Assessment Unit A2 2 - Module 5: Reproduction, Genetics and Taxonomic Diversity
Tags : General Certificate of Education, A Level and AS Level, uk, council for the curriculum examinations and assessment, gce exam papers, gce a level and as level exam papers , gce past questions and answer, gce past question papers, ccea gce past papers, gce ccea past papers

gce chat

Horizontal lines at:
Guest Horizontal lines at:
AutoRM Data:
Box geometries: