1. (a) Define sex linkage... State one example of sex linkage... Key. 1st generation. Male. Female

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1 1. Define sex linkage. State one example of sex linkage. Draw a simple pedigree chart that clearly shows sex linkage in humans. Use conventional symbols. Start with an affected woman and an unaffected man. 3. The following diagram represents a two generation pedigree showing the blood groups of the individuals. The female has been married to two different individuals. O A AB 1st generation 2nd generation B O A AB Key Male Female 2. The diagram below shows the pedigree of a family with red green colour-blindness, a sex-linked condition. 1st generation Key 1 2 normal male 2nd generation 3rd generation normal female male with condition female with condition Define the term sex-linkage. Deduce, with a reason, whether the allele producing the condition is dominant or recessive. Define the term co-dominant alleles. Deduce with a reason the probable father of 2nd generation 1. If 2nd generation 3 marries a man with blood group AB, predict the possible genotypes of the children. 4. Define the term co-dominance. (Total 6marks) A man of blood type AB and a woman of blood type B are expecting a baby. The woman s mother had blood type O. Deduce the possible phenotypes of the offspring from the cross shown below. Parent phenotypes AB B Parents genotypes Parent gametes (i) Determine all the possible genotypes of the individual (2nd generation 1) using appropriate symbols. Determine all the possible genotypes of the individual (3rd generation 4) using appropriate symbols. F 1 genotypes F 1 phenotypes 1 2

2 5. Define the term degenerate as it relates to the genetic code. (d) Apart from international cooperation, outline two positive outcomes of the Human Genome Project. State the catalytic activity of reverse transcriptase. State one use of monoclonal antibodies in diagnosis and one use in treatment. Diagnosis:... Treatment: In Zea mays, the allele for coloured seed (C) is dominant over the allele for colourless seed. The allele for starchy endosperm (W) is dominant over the allele for waxy endosperm (w). Pure breeding plants with coloured seeds and starchy endosperm were crossed with pure breeding plants with colourless seeds and waxy endosperm. State the genotype and the phenotype of the F 1 individuals produced as a result of this cross. genotype.. phenotype.. The F 1 plants were crossed with plants that had the genotype c c w w. Calculate the expected ratio of phenotypes in the F 2 generation, assuming that there is independent assortment. Use the space below to show your working. Expected ratio... (d) Explain the reasons for the observed results of the cross differing significantly from the expected results. 7. Define the term sex linkage. A male and female with normal colour vision each have a father who is colour blind. They are planning to have children. Predict, showing your working, the possible phenotypes and genotypes of male and female children.? Key male female affected male affected female Explain the relationship between Mendel s law of segregation and meiosis. (d) Distinguish the differences between animal cells and plant cells undergoing mitosis and cytokinesis. 8. State the names of the parts of the chromosome labelled (i) and on the diagram below. The observed percentages of phenotypes in the F 2 generation are shown below. coloured starchy 37% colourless starchy 14% coloured waxy 16% colourless waxy 33% The observed results differ significantly from the results expected on the basis of independent assortment. State the name of a statistical test that could be used to show that the observed and the expected results are significantly different. 3 [Source: adapted from Hartwell (editor) (2003), Genetics: from Genes to Genomes, 2nd edition, McGraw Hill, page 81] 4

3 Explain how the inheritance of chromosome 21 can lead to Down s syndrome. Explain how meiosis promotes variation in a species. 10. A farmer has rabbits with two particular traits, each controlled by a separate gene. Coat colour brown is completely dominant to white. Tailed is completely dominant to tail-less. A brown, tailed male rabbit that is heterozygous at both loci is crossed with a white, tail-less female rabbit. A large number of offspring is produced with only two phenotypes: brown and tailed, white and tail-less, and the two types are in equal numbers. (i) Deduce the pattern of inheritance of these traits. State both parents genotypes and the gametes that are produced by each during the process of meiosis. Male genotype:... Female genotype:... Male gametes:... Female gametes: Draw and label a simplified structure of a nucleotide. A genetic cross was made between pure-breeding snapdragon plants with red flowers and pure-breeding snapdragon plants with white flowers. The cross produced F 1 offspring that had only pink flowers. When the F 1 plants were self-pollinated, the resulting F 2 generation had some red, some white and some pink flowers. (i) Identify the relationship between the red and white alleles for flower colour. Deduce the genotype of the F 1 plants. (iii) Construct a Punnett grid to show the cross between two F 1 plants. (iv) Deduce the proportion of the different phenotypes of the F 2 offspring. Discuss two advantages of genetic screening. 13. The diagram below shows a DNA profiling of a family with five children. Segments of the DNA inherited by some members of the family are shown as two dark bands in each column. The DNA fragments are labelled A to F. Maternal Paternal Paternal Son 1 Son 2 Son 3 Son 4 Daughter Mother Father grandmother grandfather grandmother A B (iii) Predict the genotypic and phenotypic ratios of the F2 generation. Show your working. Outline the biotechnology used to transfer genes from one organism to another. 5 C D E F State two properties of the fragmented pieces of DNA which allow them to be separated in gel electrophoresis. Determine which DNA fragment Son 2 inherited from his mother and which from his father. From his mother:... From his father:... Identify the child that genetically most resembles one of the grandparents. 6

4 (d) Apart from determining family relationships, outline one other application for DNA profiling. 14. State one advantage and one disadvantage of genetic modification technology for crop plants. Advantage: Disadvantage: Explain the effect of base substitution mutation in sickle cell anemia. 15. (i) Define allele. Outline the consequences of a base substitution mutation. (i) Mendel crossed tall, round-seeded plants with short, wrinkled-seeded plants. All F 1 produced were tall, round-seeded plants. When F 1 plants were crossed with other F 1 plants, the F 2 generation produced many more than 1/16 short, wrinkled-seeded plants. Deduce, with reasons, the inheritance of these genes. The same cross was later repeated but gave fewer F 2 short, wrinkled-seeded plants although still more than 1/16. Outline a named statistical test that could indicate if your deduction about the inheritance of these two genes is likely to be correct. 16. List two roles of testosterone in males A boy inherited red-green colour-blindness from one of his grandfathers. Deduce, giving your reasons, which of his two grandfathers was also colour-blind. 17. Explain one use of reverse transcriptase in biotechnology. 18. State the two classes of compounds that compose chromosomes in animal cells. Outline how meiotic division results in almost an infinite genetic variation in the gametes produced. In a species of plant, tall is dominant to short and the production of round seeds is dominant to that of wrinkled seeds. The alleles are unlinked. A plant heterozygous for both characteristics is crossed with a plant homozygous for tall with wrinkled seeds. Use the letters: T allele for tall t allele for short R allele for round seed r allele for wrinkled seed. Determine the phenotypes and genotypes of the offspring of this cross. 7 8

5 (d) State how chromosome number can increase in human beings. 19. State two procedures used for the preparation of a DNA profile. The following part of a DNA profile was used as evidence in a criminal investigation. DNA profiles of two suspects labelled S1 and S2 were compared to the DNA profile taken from the scene of the crime labeled E. [Source: Solomon and Berg, (1995), The World of Biology, Saunders Harcourt Brace College, Publishers Orlando, page 238] Analyse the profiles to determine which suspect was present at the crime scene. 20. Describe the consequence of a base substitution mutation with regards to sickle cell anaemia. 9 (Total 3 marks) 21. Describe, with the aid of a diagram, the behaviour of chromosomes in the different phases of meiosis. 22. Explain how meiosis and fertilization can give rise to genetic variety. 23. Explain the use of two named enzymes in biotechnology. 24. Describe how sexual reproduction promotes genetic variation within a species. 25. Outline the differences between the behaviour of the chromosomes in mitosis and meiosis. 26. Sickle cell anemia is a serious disease caused by a single base substitution mutation. Explain how a single base substitution mutation can have significant consequences for an individual. 27. Outline a method for carrying out gene therapy, using a named example. 28. Explain how meiosis results in great genetic variety among gametes. 29. Discuss the ethical arguments for and against the cloning of humans. 30. Outline the process of DNA profiling (genetic fingerprinting), including ways in which it can be used. 31. Discuss the ethical issues for and against the use of transgenic plants Outline a basic technique for gene transfer involving plasmids. 33. Outline DNA profiling (genetic fingerprinting), including one way in which it has been used. 34. Karyotyping involves arranging the chromosomes of an individual into pairs. Describe one application of this process, including the way in which the chromosomes are obtained. 35. Outline two examples of the commercial application of enzymes in biotechnology. 36. Discuss the potential benefits and possible harmful effects of genetic modification. 37. Define the terms gene and allele and explain how they differ. 38. Outline one example of inheritance involving multiple alleles. 39. Using an example you have studied, explain a cross between two linked genes, including the way in which recombinants are produced. 40. Outline two examples of the commercial application of named enzymes in biotechnology. 10

6 41. Outline the use of transgenic techniques in agriculture, using one named animal example Up to two additional marks are available for the construction of your answers. Define the term gene linkage and outline an example of a cross between two linked genes. Describe the inheritance of ABO blood groups including an example of the possible outcomes of a homozygous blood group A mother having a child with a blood group O father. Outline sex linkage. 43. Up to two additional marks are available for the construction of your answers. Outline how the process of meiosis can lead to Down s Syndrome. (Total 3 marks) Discuss the advantages and disadvantages of genetic screening for chromosomal and genetic disorders. Describe the technique for the transfer of the insulin gene using E. coli. 44. Up to two additional marks are available for the construction of your answers. Outline the structure of DNA. Describe the effects of polygenic inheritance using two specific examples. Explain the process of transcription in eukaryotes. 45. Up to two additional marks are available for the construction of your answers. Draw and label a generalized prokaryotic cell as seen under the electron microscope. Outline the process of meiosis. Explain the role of the following hormones in the menstrual cycle: estrogen, progesterone, follicle stimulating hormone (FSH) and luteinizing hormone (LH). Genetic modification involves the transfer of DNA from one species to another. Discuss the potential benefits and possible harmful effects of one example of genetic modification in a named organism. 47. Up to two additional marks are available for the construction of your answers. Describe the structure and function of the placenta. Draw and label a diagram of the adult male human reproductive system. Discuss the implications of genetic screening. (7) 48. Up to two additional marks are available for the construction of your answers. Explain why enzymes are substrate specific and why their activity is affected by substrate concentration. Outline the use of restriction enzymes (endonucleases) and DNA ligase in gene technology. Outline the role of two enzymes found in the digestive system of humans. 49. Up to two additional marks are available for the construction of your answers. Draw and label a diagram of a dicotyledonous animal-pollinated flower as seen with the naked eye and a hand lens. Describe how meiosis results in an enormous genetic variety in the production of pollen. Using the theory of natural selection, explain how new species of dicotyledonous plants develop. 50. Up to two additional marks are available for the construction of your answers. Draw and label a diagram of the molecular structure of DNA. Explain the consequences of a base substitution mutation in relation to the processes of transcription and translation. Outline the evidence for evolution provided by homologous structures. 46. Up to two additional marks are available for the construction of your answers. Draw and label a simple diagram to show how DNA is constructed from sugars, phosphates and bases. Define the terms gene and gene mutation