6 2 (a) The diagram shows a human karyotype. 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 x 22 21 20 19 (Source: © DEPT. OF CLINICAL CYTOGENETICS, ADDENBROOKES HOSPITAL/SCIENCE PHOTO LIBRARY) (i) Which of the following identifies the human with this karyotype? (1) A female with Down’s syndrome B female with Turner’s syndrome C male with Down’s syndrome D male with Turner’s syndrome (ii) Which of the following would cause the karyotype in the diagram? (1) A non-disjunction producing a monosomy B non-disjunction producing a polysomy C translocation producing a monosomy D translocation producing a polysomy Turn over 7 (b) (i) The table shows the chromosome number and chromatid number of some of the cells formed during oogenesis in humans. Cell type Chromosome number Chromatid number ovum 23 23 primary oocyte 46 92 secondary oocyte 23 46 Which of the cells are haploid? (1) A ovum and primary oocyte B ovum and secondary oocyte C primary oocyte and secondary oocyte D ovum alone (ii) Explain how meiosis produces new combinations of alleles in gametes. (4) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (Total for Question 2 = 7 marks)