2016 VJC H2 Biology Prelims Paper 1 Questions

1      VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION 2017 NAME : ____________________________________ CT CLASS : ____________________________________ H2 BIOLOGY 9744/1 Paper 1 Multiple Choice 1 hour Additional material: Multiple choice answer sheet READ THESE INSTRUCTIONS FIRST Write your name, exam number on the answer sheet provided. Do not use any staples, paper clips, highlighters, glue or correction fluid. There are 30 questions in this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate answer sheet. Read the instructions on the answer sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this paper. The use of an approved scientific calculator is expected, where appropriate. This document consists of 24 printed pages, including cover page

2      1 Which of the following is a false statement regarding centrioles and ribosomes? A Both are non-membrane bound organelles. B Only centrioles are present in a cell undergoing mitosis. C Both are present in dividing and non-dividing animal cells. D Under high temperature, bot h will be denatured as they have a proteinaceous component. 2 Fig 2 shows three cell organelles W, X and Y. Which of the following statements about these organelles is true? A Only organelle Y contains RNA. B Only organelle W contains carbohydrates and phospholipids. C Organelle X has 80S ribosomes whereas organelle Y has 70S ribosomes. D Organelles X and Y have double membrane whereas organelle W has a single membrane.

3      3 Which set of factors shown below will produce the least fluid cell surface membrane? A ● High proportion of cholesterol ● High temperature B ● Low proportion of phospholipids with saturated fatty acids ● High temperature C ● Low proportion of phospholipids with unsaturated fatty acids ● Low temperature D ● High proportion of phospholipids with unsaturated fatty acid ● Low temperature 4 Fig 4 shows a repeating unit found in a biomolecule. Fig 4 In which of the following biomolecules, w ould one expect to find the above repeating unit? X Absent √ Present Cellulose Glycogen Amylose Collagen A X X √ X B √ X √ X C √ X X √ D X √ √ X

4      5 Fig 5 below is an electron micrograph of a stained fiber of deoxyhemoglobin S (HbS). Fig 5 [From G. Rykes, R.H. Crepeau, and S.J. Edelstein. Nature 272(1978):509.] Source: http://www.nslc.wustl.edu/sicklecell/part2/molecular.html Which of the following statements is true? A Mutation in the red blood cell results in the production of HbS which precipitates out as long rigid fibers under low oxygen concentration. B The long HbS molecule is insoluble due to its large molecular size and this results in the sickling of red blood cells. C The aggregration of HbS molecules, under low oxygen concentration, causes the fiber to be precipitated out of solution, resulting in the sickling of red blood cells. D Under low oxygen concentration, HbS molecules form a tr iplex helix structure, causing the cell membrane of the red blood cells to be more rigid and hence they sickled.

5      6 The graph shows the effect of increasing the concentration of substrate on the rate of enzyme catalysed reaction. What is limiting the rate of the enzyme-catalysed reaction at 1, 2, 3 and 4 on the graph? 1 2 3 4 A enzyme concentration substrate concentration competitive inhibitor non-competitive inhibitor B enzyme concentration substrate concentration non-competitive inhibitor competitive inhibitor C substrate concentration enzyme concentration competitive inhibitor non-competitive inhibitor D substrate concentration enzyme concentration non-competitive inhibitor competitive inhibitor

6      7 Many people are opposed to the use of em bryonic stem cells on ethical grounds. Researchers have come up with a way of dev eloping embryonic stem cells from a patient’s cells. The cultured embryonic cells can then be used to treat the patient. Fig 7 shows the process. Fig 7 Which of the following options is true? 1 The patient will not show any immune response when the specific cell types developed from the embryonic stem cells are introduced into the patient. 2 No embryo is destroyed in the process of harvesting the embryonic stem cells. 3 The cultured embryonic stem cells can be used for reproductive cloning. 4 The moral concern of the embryo bei ng an individual is not an issue as the embryonic cells come from the patient. A 1 only B 1 and 4 only C 2 and 3 only D 1, 2, 3 and 4

7      8 The graph below shows the relative amount of mRNA for the production of histone protein at different times throughout a cell cycle. Using your knowledge of t he cell cycle and the information in the graph, it is correct to state that A DNA replication occurs most actively in the G1 phase. B histone genes are highly active throughout the cell cycle. C histone protein synthesis occurs simultaneously with DNA synthesis. D histone protein is not present in the cell during the G1 and G2 phases. 9 The following are descriptions of different regions of chromosomes. 1 Non-coding sequences are onl y located within the genes. 2 The ends of the chromosomes can be lengthened using a RNA template. 3 Sequences found in the mi ddle of the chromosomes are always integral to the positioning of spindle fibres. 4 Each chromosome comprise of ti ght packing of several DNA molecules around histone proteins and scaffold proteins. Which of the statements above apply only to a eukaryotic chromosome? A 2 only B 1 and 3 only C 3 and 4 only D All of the above

8      10 The sequence below depicts the template st rand of a hypothetical gene. The exons are in bold type. An allele for this gene codes for a polypep tide with only five amino acids. This is caused by a mutation in one of the exons. Which of the following describes the change(s) that results in the formation of the shorter polypeptide? A Deletion of one adenine B Addition of two cytosine C Substitution of thymine with adenine D Addition of cytosine and removal of adenine 11 The following events occur during transcription. P. Bonds break between complementary bases. Q. Bonds form between complementary bases. R. Phosphodiester bonds form. S. Free nucleotides pair with complementary nucleotides. Which options correctly depicts the frequency of the events occurring in the nucleus? Occurs once Occurs twice A P, R, S Q B Q, R, S P C R, S P, Q D P, S Q, R

9      12 The c-myc proto-oncogene on chromosome 8 codes for the c-myc protein, a transcription factor that promotes cell proliferation. In cells that are induced to differentiate, the gene is expressed at a very low level. The figure below shows the involvement of two enzymes in regulating the expression of this gene. Which one of the following statement is true? A A hyperactive enzyme 2 can lead to tumor formation. B Enzyme 1 is only functional in both stem cells and cancerous cells. C Enzyme 2 can be recruited by methylation of c-myc gene. D Both enzymes 1 and 2 carry out chemical modification on the DNA molecule. 13 Which of the following mechanism can reduce the amount of polypeptides produced from a given mRNA molecule? A Addition of ubiquitin to the mRNA B Increasing the region of DNA methylation C Preventing activators from binding to enhancers D Inhibiting the activ