SGSS Pure Biology Prelim 2024 Paper 2

St. Gabriel’s Secondary School 2024 ‘O’ Preliminary Examination Subject : Biology Paper : 6093 / 2 Level/Stream : Sec 4 Express Duration : 1 hour 45 min Date : 20 August 2024 Setter : Ms Jane Zhou ▪ Section B: Answer one question. ▪ You are advised to spend no longer than 50 minutes on Section A. INFORMATION FOR CANDIDATES The number of marks of each part-question is shown in brackets. This question paper consists of 20 printed pages including this cover page. Name: …………………………………………… ( ) Class: Sec ……………… READ THESE INSTRUCTIONS FIRST Write your name, 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, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided. Section B Answer one question. Write your answers in the spaces provided. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Sect. A / 70 Sect. B / 10 TOTAL / 80

2 SGSS/BIOP2/4EPrelim/2024 Section A Answer all questions. 1 Food poisoning can be caused by bacteria -infested foods that have been left out in the open for a long time. One such bacteria is Campylobacter. People with Campylobacter infections in the intestines are often prescribed a medicine called erythromycin. Erythromycin is an antibiotic that is known to reduce Campylobacter bacteria counts. Fig. 1.1 below shows the concentration of Campylobacter protein after erythromycin intake. Fig. 1.1 (a) Patients are advised to be administered erythromycin every 6 hours. Suggest the concentration of Campylobacter protein at the sixth hour by extending the line, before the next dose of erythromycin is administered. ………………………………………….………………………………............................ [1] (b) Describe and explain the results in Fig. 1.1, from 2 h to 4 h after erythromycin intake. ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………….………………………………............................ [4] 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 Concentration of Campylobacter protein / 100 cells per ml Duration after erythromycin intake / h

3 SGSS/BIOP2/4EPrelim/2024 (c) Some Campylobacter samples have been obtained from the patient before taking erythromycin and have been placed under the light microscope for research. Fig. 1.2 shows the possible appearance of the Campylobacter bacterium obtained from the patient before taking erythromycin. Draw label lines to the Campylobacter bacterium obtained in Fig. 1.2 and annotate your labels to identify two structures absent in a typical virus. …………………………………………......... ..... Fig. 1.2 [2] (d) Campylobacteriosis is an illness caused by the Campylobacter bacteria. Development of an effective vaccine for the prevention of campylobacteriosis has been ongoing for over 20 years. In recent research, scientists have found that the Campylobacter vaccination not only reduces intestinal disease but also prevents stunted growth in infants. The production of the vaccine involves the culturing, inactivat ion of Campylobacter strains, and removal of toxins to produce a “whole-cell” vaccine. (i) Suggest and explain whether Campylobacter infections are infectious. …………………………………………………...……………………............................ …………………………………………………...……………………............................ …………………………………………………...……………………............................ ……………………………………………………………………............................ [2] (ii) Suggest how the vaccine prevents Campylobacter infection in an individual. …………………………………………………...……………………............................ …………………………………………………...……………………............................ …………………………………………………...……………………............................ …………………………………………………...……………………............................ …………………………………………………...……………………............................ …………………………………………………...……………………............................ ……………………………………………………………………............................ [3] [Total: 12]

4 SGSS/BIOP2/4EPrelim/2024 2 Cacti are desert plants that grow in water scarce areas. The leaves of cacti are modified into spines shown in Fig. 2.1 below. Fig. 2.1 (a) Suggest how the leaves in a cactus plant shown in Fig. 2.1 prevents wilting in water scarce environments. ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………….………………………………............................ [2] (b) Fig. 2.2 shows the cross section of a cactus plant. Use label lines and labels to identify the position of the xylem and phloem in Fig. 2.2 below. Fig. 2.2 [2]

5 SGSS/BIOP2/4EPrelim/2024 Fig. 2.3 shows a mangrove tree growing in coastal swamp. Fig. 2.3 The roots of the mangrove are specially modified to erect out of the ground as air spaces in the soil are always filled with water. Arrows M, N, and P represent the movement of gases into and out of the tree during the day. Gas M only moves out in the day. (c) Name gas M and gas P in Fig. 2.3. For each gas state the chemical process in the tree which produces it. gas M:……………………………… chemical process:……………………………… gas P:……………………………… chemical process:……………………………… [2] (d) Active transport is a process which occurs in most plant roots. Suggest why mangrove roots may have difficulty in carrying out this process. ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………….………………………………............................ [2] [Total: 8] M N P mud surface root erect root mangrove tree

6 SGSS/BIOP2/4EPrelim/2024 3 Fig. 3.1 shows how a blocked blood vessel outside the heart can be bypassed using an artificial blood vessel. Fig. 3.1 (a) Name the blocked blood vessel and vessel A respectively. vessel A ……………………………...……...……………………....................... blocked vessel ……………………….…………………………………........................ [2] (b) Describe how the blocked blood vessel in Fig. 3.1 can affect the normal functioning of the heart. ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………………………...……………………............................ ………………………………………….………………………………............................ [2] (c) Sometimes, instead of using an artificial blood vessel, a vein from another part in the patient’s body is used. Suggest two ways in which a vein might not be suit