2025 VJC H2 Biology Prelim P1

VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION 2025 HIGHER 2 NAME : ……………………………………………………….………………. CT CLASS: ………………..……… BIOLOGY Paper 1 Multiple Choice 9744 / 01 22/09/2025 1 hour Additional Materials: Multiple Choice Answer Sheet 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. 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. 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 18 printed pages. [Turn over]

2 1 What is correct about the synthesis and release of the glycoprotein mucin in epithelial cells lining the intestines? 1 The protein is produced on free ribosomes and a carbohydrate chain is added in the Golgi body. 2 The glycoproteins are packed into vesicles in the Golgi body forming lysosomes. 3 Secretory vesicles containing the glycoprotein move from the Golgi body and fuse with the cell surface membrane. A 1, 2 and 3 B 1 and 3 only C 1 only D 3 only 2 Hydroxyproline is synthesised by addition of an – OH group to the R -group of the amino acid proline. Hydroxyproline is a major component of collagen and has an important role in increasing the stability of its structure. Which statement explains why the addition of an –OH group to proline could increase the stability of collagen? A It strengthens hydrogen bonding between R -groups of adjacent polypeptide chains, resulting in a tertiary structure that is more resistant to heat denaturation. B It increases the number of sites available for the formation of hydrogen bonds within the secondary structure of collagen, resulting in more stable alpha helices. C The –OH group changes proline’s ring shape, locking collagen into a stable triple helix conformation. D It strengthens the quaternary structure of collagen by increasing the number of sites for hydrogen bonding between R-groups of distantly separated amino acids within the same polypeptide chain. 3 Which statement about fatty acids is correct? A Fatty acids are amphoteric molecules because they have a polar –COOH group at one end and a long non-polar hydrocarbon chain. B All unsaturated fatty acids are polyunsaturated, meaning they have two or more C=C double bonds in their hydrocarbon chains. C The complete oxidation of fatty acids releases more energy per gram than the complete oxidation of polysaccharides because fatty acids are less reduced. D Fatty acids stored as components of fats in adipose tissue have no direct effect on the osmotic potential of the cytoplasm.

3 4 Which statement correctly describes how an enzyme acts on its substrate? A Binding and catalytic amino acids at the active site form covalent interactions with complementary chemical groups on the substrate molecule. B Conformational change of both enzyme and substrate molecules occurs upon the binding of substrate. C Most enzymes catalyse irreversible reactions as they can only bind to their substrate molecules and not their product molecules. D Activation energy of an enzyme-catalysed reaction may be lowered by the use of metal ion cofactors at the enzyme’s active site. 5 Which region on the graph shows the activation energy of an enzyme-catalysed reaction?

4 6 An enzyme experiment was conducted, with the graph showing the concentration of substrate remaining each minute after the enzyme was added to the substrate. Graph W shows the results obtained at a temperature of 40º C. Some modifications were made in subsequent experiments and results recorded in two separate graphs X and Y. Which statement best explains the graphs above? A The temperature used for experiment X was higher than W. B A less concentrated reaction mixture was used for X than W. C Experiment Y used a lower initial substrate concentration than W. D The pH used for experiment Y was closer to the enzyme’s optimum than in W.

5 7 A scientist investigated the rate of breakdown of hydrogen peroxide. Four experiments were carried out using different reaction mixtures. In each experiment, the concentration of the enzyme (if present) and all physical conditions such as volumes, temperature and pH were kept the same. • substrate only • substrate + enzyme • substrate + enzyme + competitive inhibitor • substrate + enzyme + non-competitive inhibitor The results are sketched in the graph. 1 In experiment 1, the graph plateaus off at high substrate concentration due to high activation energy. 2 In experiment 2, the maximum rate of breakdown of hydrogen peroxide is similar to experiment 1 because competitive inhibition can be overcome by the substrate. 3 In experiment 3, the maximum rate of breakdown of hydrogen peroxide can be increased by adding more substrate. 4 In experiment 4, the lower rate of breakdown of hydrogen peroxide is due to a permanent reduction in active enzyme molecules. Which statement(s) correctly explain the patterns observed? A 1 and 3 B 2 and 4 C 2 only D 3 and 4

6 8 Anti-cancer therapy that targets dividing cells can reduce the numbers of different blood cell types in a person’s body. Which statement about blood stem cells is correct? A As blood stem cells are totipotent, all the blood cell types can be produced to restore circulating differentiated blood cells to their normal numbers. B As blood stem cells are undifferentiated, they are unaffected by anti -cancer therapy and will continue to renew themselves to gradually bring numbers of blood cells back to normal. C Blood stem cells removed from the bone marrow, if transplanted to the site where the cancer is located, will differentiate into the cell types of the new location. D Blood stem cells that are collected from a person before anti -cancer therapy and are then put back into the same person after therapy are able to produce new blood cells. 9 The figure shows an electronmicrograph of DNA undergoing replication. Which of the following correctly describes the region indicated by the arrow? 1 A mixture of DNA and RNA can be found. 2 Non-enzymatic proteins can be found. 3 DNA can be double-stranded or single-stranded. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

7 10 The figure shows protein synthesis. Which row correctly identifies the labels of X, Y and Z, as well as the direction of RNA pol movement? X Y Z direction of RNA pol movement A 5’ N-terminal 5’  B 3’ N-terminal 3’  C 5’ C-terminal 3’  D 3’ C-terminal 5’ 

8 11 The figure shows the structure of a bacteriophage. Which row correctly matches the function of the labelled structures P, Q and R? P Q R A carries genetic information for passing down to daughter cells for the transfer of genetic material to the host cell for adsorption to the host cell surface B double stranded DNA contractile sheath tail fibres C for integration into the host cell chromosome for the injection of genetic material into the host cell for conformational changes enabling entry of the viral core D carries genetic information for lysozymes contracts to drive a hollow tube through the host cell wall attach to receptors on the host cell surface 12 The cell cycle includes mitosis. What are features of this type of nuclear division? 1 formation of two nuclei each with the same chr