2024 ASRJC H2 Bio P3 QP

ASRJC BIOLOGY DEPT 9744//2024/J2PRELIM/P3 [Turn over H2 ANDERSON SERANGOON JUNIOR COLLEGE HIGHER 2 2024 JC2 PRELIMINARY EXAMINATIONS CANDIDATE NAME CLASS INDEX NUMBER BIOLOGY 9744/03 PAPER 3 LONG STRUCTURED AND FREE RESPONSE QUESTIONS Candidates answer on the Question Paper. No Additional Materials are required. 10 SEPTEMBER 2024 TUESDAY 2 HOURS READ THESE INSTRUCTIONS FIRST Write your name and class on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graph Do not use paper clips, highlighters, glue or correction fluid. Section A Answer all questions in the spaces provided on the Question Paper. Section B Answer any one question in the spaces provided on the Question Paper. 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. This document consists of 24 printed pages. For Examiner’s Use 1 / 30 2 / 10 3 / 10 4 / 5 / 25 Total / 75

2 ASRJC BIOLOGY DEPT 9744//2024/J2PRELIM/P3 Section A Answer all the questions in this section. 1 Malaria is a disease caused by the Plasmodium parasite. There are four species of the Plasmodium parasite, of which Plasmodium falciparum is responsible for most of the deaths from this disease. Fig.1.1 shows part of the life cycle of P. falciparum, which requires two hosts. A female mosquito carrying P. falciparum injects the parasite, in a form known as a sporozoite, into the bloodstream of an uninfected person. The P. falciparum parasite multiplies in a liver cell before emerging as a different form, known as a merozoite, wrapped in the liver cell surface membrane. It enters a red blood cell and multiplies before causing the rupture of the red blood cell, releasing more parasites. Fig. 1.1 A. B.

3 ASRJC BIOLOGY DEPT 9744//2024/J2PRELIM/P3 [Turn over (a) State two features, visible in Fig. 1.1B, that indicate that P. falciparum is eukaryotic. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… [2] (b) To control the spread of malaria, re search has been directed towards the development of a malarial vaccine. Much of this research relies on the fact that P. falciparum has different forms in its life cycle. Researchers were able to extract both the sporozoite form (the form injected by mosquitoes) and the merozoite form (the form that leaves the liver, before entering red blood cells) of P. falciparum. With reference to Fig. 1.1 A, su ggest why researchers finally chose to use the sporozoite form of P. falciparum instead of the merozoite form in the malarial vaccine. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… [2]

4 ASRJC BIOLOGY DEPT 9744//2024/J2PRELIM/P3 (c) In another trial, a naturally occurring mutant form of P. falciparum parasite discovered in Africa was tested for use as a vaccine against malaria. The mutant parasite develops normally in mosquito es. In humans, however, the mutant P. falciparum infects liver cells but does not multiply and cannot enter red blood cells. An investigation was conducted to test this vaccine using mice. Four test groups of 10 mice each were injected (inoculated) with mutant P. falciparum cells, followed by booster doses every six months after the first inoculation. The effectiveness of the vaccine was then tested by injecting non-mutant (wild type) P. falciparum cells into all the mice. Table 1.1 shows the results of the investigation. Table 1.1 number of mutant P. falciparum cells given to mice percentage of mice not infected by non-mutant (wild type) P. falciparum test group first inoculation first booster inoculation second booster inoculation 1 0 0 0 0 2 50 000 25 000 25 000 100 3 10 000 10 000 10 000 100 4 10 000 10 000 0 70 (i) Evaluate whether the results of this investigation is sufficient for researchers to recommend an effective vaccination plan against malaria. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. [4]

5 ASRJC BIOLOGY DEPT 9744//2024/J2PRELIM/P3 [Turn over (ii) Volunteers who were injected with killed mutant P. falciparum cells produced antibodies, which provided some protection against malaria. Outline the events that occur following injection of the killed mutant P. falciparum, which lead to the eventual production of antibodies. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. [5]

6 ASRJC BIOLOGY DEPT 9744//2024/J2PRELIM/P3 (d) While vaccination provides protection against malaria, the severity of a person's malarial infection can be influenced by the type of red blood cells (RBCs) present in their blood. Haemoglobin (Hb) is the protein found in RBCs that is responsible for delivery of oxygen to tissues. HbS is a mutant form of the normal HbA protein and is responsible for causing sickle cell anaemia. Individuals who carry one copy of the HbS allele are protected against severe malaria. From your knowledge of Hb structure, explain how having HbS protein protects such individuals against severe malarial infection. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… [4] (e) The human ABO blood typing system is based on the presence or absence of A and B antigens on the surface of RBCs. A and B antigens are glycoproteins. The ABO blood type is controlled by a single gene with three alleles: O, A and B. • Individuals with RBC genotype AO and AA have type A blood with A antigens on the surface of their RBCs. • Individuals with RBC