2014 HCI H1 Biology Prelims P2 Questions

This document consists of 11 printed pages and 1 blank page. HWA CHONG INSTITUTION JC2 Preliminary Examinations Higher 1 CANDIDATE NAME CT GROUP 13S____ CENTRE NUMBER INDEX NUMBER BIOLOGY Paper 2 8875/02 2 September 2014 2 hours INSTRUCTIONS TO CANDIDATES Write your name, CT group, centre number and index number in the spaces provided at the top of this cover page. SECTION A This section contains four questions. Answer ALL questions. Write your answers on the lines / in the spaces provided. SECTION B This section contains two questions. Answer any ONE question. Your answers must be in continuous prose, where appropriate. Write your answers on the writing paper provided. Begin each part on a fresh sheet of writing paper. A NIL RETURN is required. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or question part. You may use a calculator. You are reminded of the need for good English and clear presentation in your answers. For Examiners' Use 1 / 10 2 / 10 3 / 10 4 / 10 5 / 6 / 20 Total / 60

© Hwa Chong Institution 2014 8875 H1 Biology / Preliminary Examinations / Paper 2 2 --- BLANK PAGE --- 1

© Hwa Chong Institution 2014 8875 H1 Biology / Preliminary Examinations / Paper 2 2 SECTION A: STRUCTURED QUESTIONS QUESTION 1 Fig. 1.1 shows the electron micrograph of part of a plasma cell with organelles A, B and C labelled. Plasma cells secrete proteins that are involved in immune responses. Fig. 1.1 (a) (i) Name and state the function of organelles A and B. [2] (ii) Explain why there is an abundance of organelle C in the plasma cell. [2] A B C cell membrane

© Hwa Chong Institution 2014 8875 H1 Biology / Preliminary Examinations / Paper 2 3 (b) Explain how the structure of the cell membrane relates to its role in maintaining the internal environment of the plasma cell. [3] Macrophages are another important cell type in the immune system where one of their functions is to remove cellular debris. (c) Describe how macrophages engulf and digest cellular debris. [3] [Total: 10]

© Hwa Chong Institution 2014 8875 H1 Biology / Preliminary Examinations / Paper 2 4 QUESTION 2 Fig. 2.1 outlines the processes in photosynthesis with structures A and B labelled. Fig. 2.1 (a) Describe how light is harvested at structures A and B. [2] A herbicide, triazine, acts on weeds by binding to a specific protein associated with structure A, blocking the movement of electrons between electron carriers in the electron transport chain. (b) Explain the effect of triazine on photosynthesis. [2]

© Hwa Chong Institution 2014 8875 H1 Biology / Preliminary Examinations / Paper 2 5 A process known as photorespiration also takes place in photosynthetic cells. In this process, oxygen competes with carbon dioxide for the active site of the enzyme Rubisco. Fig. 2.2 outlines the process of photorespiration. Fig. 2.2 (c) (i) Describe and explain the effects of an increase in oxygen concentration on photosynthesis. [3] (ii) Suggest why the process outlined in Fig. 2.2 is known as photorespiration. [2] 2 ribulose bisphosphate (5C) + 2 O2 2 phosphoglycolate (2C) 2 glycerate 3-phosphate (3C) 1 glycerate 3-phosphate (3C) O2 CO2 Calvin cycle RuBP carboxylase

© Hwa Chong Institution 2014 8875 H1 Biology / Preliminary Examinations / Paper 2 6 Some plants known as C4 plants use an enzyme PEP carboxylase, instead of Rubisco, to fix carbon dioxide. (d) Suggest why photorespiration does not occur in these plants. [1] [Total: 10]

© Hwa Chong Institution 2014 8875 H1 Biology / Preliminary Examinations / Paper 2 7 QUESTION 3 In his book The Origin of Species , Charles Darwin hypothesised a logical and well-supported explanation for evolution. It articulated descent with modification by natural selection. (a) Outline what is meant by descent with modification by natural selection. [3] The seahorse Hippocampus shown in Fig. 3.1 is an unusual small fish. It gives birth to live young and it is the male rather than the female that becomes pregnant. Fig. 3.1

© Hwa Chong Institution 2014 8875 H1 Biology / Preliminary Examinations / Paper 2 8 (b) Explain why variation is important in selection. [3] In one species of Hippocampus, a type of natural selection called disruptive selection occurs. (c) (i) Using the axes provided, sketch a graph to show the distribution in the size of Hippocampus as a result of discruptive selection. [1] (ii) Explain how disruptive selection has been maintained in this species of Hippocampus. [3] [Total: 10] frequency of Hippocampus size of Hippocampus

© Hwa Chong Institution 2014 8875 H1 Biology / Preliminary Examinations / Paper 2 9 QUESTION 4 Fig. 4.1 shows the different developmental pathways of a human embryonic stem cell (ESC). Fig. 4.1 (a) (i) Explain the significance of forming more stem cells from an ESC. [2] (ii) Suggest how an ESC differentiates to form specialised cell types. [2] embryonic stem cell forming more stem cells forming different specialised cell types