2017 RVHS H2 Biology Prelims Paper 3 Answers

River Valley High School Pg 1 of 20 Year 6 H2 Biology 9744 Paper 3 2017 Preliminary Examination II RIVER VALLEY HIGH SCHOOL YEAR 6 PRELIMINARY EXAMINATION II CANDIDATE NAME CENTRE NUMBER S CLASS INDEX NUMBER H2 BIOLOGY 9744/03 Paper 3 Long Structured and Free-response Questions 20 Sep 2017 2 hours Additional Materials: Writing Paper READ THESE INSTRUCTIONS FIRST Write your Centre number, index number and name in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Section A Answer all questions in the spaces provided on the Question Paper. Section B Answer any one question on the separate writing paper provided. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. At the end of the examination, fasten all your work securely together. The number of marks is gi ven in brackets [ ] at the end of each question or part question. For Examiner’s Use Section A 1 /19 2 /18 3 / 13 Section B 4 or 5 /25 Total / 75 _____________________________________________________________________ This document consists of 18 printed pages.

River Valley High School Pg 2 of 20 Year 6 H2 Biology 9744 Paper 3 2017 Preliminary Examination II Section A Answer all the questions in this section. 1 The Galapagos Islands is an archipelago approximately 1400 kilometers off the Western coast of Ecuador. It consists of more than 40 islands, including the small and isolated island Daphne Major. The map of the islands, and its location in relation to mainland Ecuador and Cocos Island, is shown in Fig. 1.1. Fig. 1.1 There are now at least 13 species of finches on the Galapagos Islands, each filling a different niche on different islands. All of t hem evolved from one ancestral species, which colonised the islands only a few million years ago. Molecular analysis was carried out on the nucleotide sequences of the Galapagos Islands finches and the Cocos finch, found on the island of Cocos, 830 km North-east of the Galapagos Islands. Fig. 1.2 shows the phylogeny of these finches as constructed from the molecular data obtained.

River Valley High School Pg 3 of 20 Year 6 H2 Biology 9744 Paper 3 2017 Preliminary Examination II Fig. 1.2 (a) Explain how DNA sequences can be used to determine evolutionary relatedness between species. [2] 1. Compare homologous DNA sequences/ same gene; 2. found in different species; 3. The fewer the differences in the DNA sequences of homologous genes between species, the more closely related the species are (vice-versa);; (b) Suggest how the Cocos finch might be derived from the same common ancestor as the Galapagos finches, despite its lack of proxi