2016 RVHS H2 Biology Prelims Paper 2 Answers

River Valley High School Pg 1 of 22 Year 6 H2 Biology 9648 Paper 2 2016 Preliminary Examination I RIVER VALLEY HIGH SCHOOL YEAR 6 PRELIMINARY EXAMINATION II CANDIDATE NAME CENTRE NUMBER S INDEX NUMBER H2 BIOLOGY 9648/02 Paper 2 Core Paper 15 Sep 2016 2 hours Additional Materials: Answer Paper READ THESE INSTRUCTIONS FIRST Write your index number and name on all the work you hand in. 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 answer paper provided. Circle the question attempted on the cover page. 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 given in brackets [ ] at the end of each question or part question. For Examiner’s Use Section A 1 / 10 2 / 10 3 / 9 4 / 10 5 / 10 6 / 11 7 / 10 8 / 10 Section B 9 or 10* / 20 Total / 100 _____________________________________________________________________ This Question Paper consists of 23 printed pages.

River Valley High School Pg 2 of 22 Year 6 H2 Biology 9648 Paper 2 2016 Preliminary Examination II Section A (80 marks) Answer all the questions in this section. 1 Fig. 1.1 shows photomicrographs of a zebrafish cell undergoing mitotic cell division. Fig. 1.1 (a) Explain the significance of mitosis in the development of zebrafish. [2] 1. Produces genetically identical cells; 2. resulting in genetic stability in a zebrafish; 3. Allows growth; 4. into a multicellular zebrafish; 5. Allows replacement of worn-out / damaged tissues; Reject: asexual reproduction as context given is zebrafish (b) (i) Identify stage A. [1] Telophase;; (ii) With reference to Fig. 1.1, describe two visible features that support the identification in 1(b)(i). [2] 1. Chromosomes de-condense into chromatins;; 2. Chromatin are gathered at opposite poles of the cell;;

River Valley High School Pg 3 of 22 Year 6 H2 Biology 9648 Paper 2 2016 Preliminary Examination II (iii) Explain the significance of stage D in cell division. [2] 1. Cytokinesis; 2. Separation of cytoplasmic materials; 3. and chromosomes; 4. into two daughter cells; (c) Explain why sister chromatids are genetically identical. [3] 1. Sister chromatids are formed by DNA replication (in S phase); 2. which is semi conservative; 3. The two parental strands separate; 4. Each parental strand act as a template; 5. for the synthesis of a daughter strand; 6. via complementary base pairing; [Total: 10] 2 Human Immu