VJC 2023 H2 9744 P1 QP Ans

1 CANDIDATE NAME CT GROUP VICTORIA JUNIOR COLLEGE PRELIMINARY EXAMINATION HIGHER 2 Answers – last page ……………………………………………….………….. …………………………….. BIOLOGY 9744/01 Paper 1 Additional Materials: Multiple Choice Answer Sheet 25 September 2023 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name and class on the Answer Sheet in the spaces provided. WRITE and SHADE your EXAM NUMBER on the Answer Sheet in the spaces provided. There are thirty questions on 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 booklet. The use of an approved scientific calculator is expected, where appropriate. This document consists of 20 printed pages

2 1 The electron micrograph shows two organelles (not to the same scale) present in a plant cell. Organelle P Organelle Q Which of the following options is false of the organelles P and Q? A Only organelle P contains enzymes. B Vesicles can be pinched off from both organelles. C Both organelles can fuse with vesicles coming from another organelle in the cell. D Organelle P is involved in synthesis of phospholipids while Q is involved in synthesis of glycoprotein. 2 How many rows in the table show correctly the chemical processes that occur in the organelles found in an animal cell? Nucleus Mitochondrion Rough ER polymerisation phosphorylation glycosylation replication reduction polymerisation translation transcription phosphorylation transcription oxidation translation A 1 B 2 C 3 D 4

3 3 The chart shows the concentration of some substances outside the cell surface membrane, in the cytoplasm, in two organelles 1 and 2 of a plant cell. Which statement about the direction of movement of these substances and the process by which they are moving is correct? A Phosphate and ATP are entering the organelles 1 and 2 by active transport. B ATP is leaving organelle 1 by facilitated diffusion, water is leaving the plant cell by osmosis. C Phosphate and ATP are leaving organelle 2 by facilitated diffusion, water is leaving the plant cell by osmosis. D Phosphate is entering the organelle 1 by facilitated diffusion, water is entering organelle 1 by osmosis 4 Which row matches correctly each molecule to a type of bond that is present? ester bond hydrogen bond disulfide bond A amylase Haemoglobin catalase B glycerol glycogen collagen C lipid amylose haemoglobin D Phospholipid cellulose antibody

4 5 Approximately half of the total protein in a pea seed consists of the storage protein vicilin. Below are statements describing vicilin: ● Each molecule of vicilin is made up of three identical polypeptides. ● Each polypeptide is made up of two β -pleated sheet regions with linking α-helix regions, folded into a specific shape. ● This allows the three polypeptides to pack together into a compact, flat storage molecule, as shown below. Based on the information provided, which of the following can be deduced about vicilin? A The primary structure of the polypeptides has repeating amino acid sequences. B The most significant level of organisation in vicilin is the secondary structure. C The β-pleated sheet and α -helix regions are formed by interchain hydrogen bonds at regular intervals between adjacent polypeptide chains. D Vicilin is coded by three genes, forming a major component of the protein content within the seed.

5 6 A student investigated the effect of urea on the activity of the enzyme urease. Urease catalyses the following reaction: urea + water ammonium carbonate To find out the rate of the reaction by measuring the amount of ammonium carbonate produced in 10 minutes in different urea concentrations, the student carried out titrations using dilute sulfuric acid and recorded down the volumes of acid needed to neutralise the ammonium carbonate. The results were used to produce the graph below. Which statements are correct? 1. At P, the rate of reaction is limited by the concentration of urease. 2. At Q, all the urease active sites are occupied by urea molecules. 3. R represents the affinity of the urease for the urea molecules. 4. At S, not all the urea molecules are occupying the active sites of urease. A 1 and 4 only B 2 and 3 only C 1, 2 and 4 D 1, 3 and 4

6 7 Differentiating stem cells may be used to replace damaged tissues in mice. For example, neural precursor cells derived from embryonic stem cells can give rise to different types of functional nerve cells (neurons and dendrocytes) in the brains of mice. One risk associated with this treatment is that small numbers of embryonic stem cells remain within cultures of neural precursor cells. When introduced to mice, embryonic stem cells can form tumours known as teratomas. Formation of teratomas in the heart or brain is fatal. Ceramide and S1P are molecules that have opposite effects when they bind to protein receptors on stem cells. Binding of ceramide to stem cells promotes cell death, while binding of S1P to stem cells promotes survival by inhibiting cell death. Adding a combination of ceramide and S1P to cultures of neural precursor cells can eliminate the risk of teratoma formation without making the stem cells less effective at replacing damaged brain tissue. Which row provides a possible explanation for this? Pluripotent stem cells Multipotent stem cells A Have receptors for ceramide and S1P Have receptors for ceramide but not for S1P B Have receptors for ceramide but not for S1P Have receptors for ceramide and S1P C Do not have receptors for ceramide or for S1P Have receptors for S1P but not for ceramide D Have receptors for S1P but not for ceramide Do not have receptors for ceramide or for S1P 8 The figure below shows the process of DNA replication. Which of the following statements is/are true about the process? 1. Q is located around the origin of replication. 2. R is synthesized discontinuously towards the replication fork. 3. T is a short DNA primer for DNA polymerase to elongate. 4. S is synthesized continuously until the end of the strand. A 1 only B 2 only C 1 and 4 D 2 and 3

7 9 The diagram below shows a codon table. Part of the coding strand controlling the production of a polypeptide includes the nucleotide sequence below. Using the information provided, which of the following statements shows the effect of the type of mutation on the DNA sequence? A A substitution mutation at position 10 with adenine can cause the production of a truncated protein. B A deletion of a nucleotide at position 12 has no effect on the primary structure. C A substitution mutation at position 9 with adenine would produce no alteration in the polypeptide sequence. D An insertion of a thymine after position 3 can cause a premature termination of translation.

8 10 Cyclins are important regulatory proteins that control the cell cycle together with cyclin- dependent kinases. Their presence at the precise timing will help to ensure proper cell division and maintain genomic stability. The figure below shows the changes of concentration of different cyclins in the cell cycle. What can account for the changing concentration of different cyclins? 1. Ubiquitylation of cyclins 2. DNA methylation 3. Repressor binding to operator 4. Activator binding to promoter 5. His