DHS 2023 H2 Prelim Paper 1

© DHS 2023 9744/01 [Turn over Name: Centre/Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination Year 6 H2 BIOLOGY 9744/01 Paper 1 Multiple Choice Questions 25 September 2023 Additional Materials: Multiple Choice Answer Sheet 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your centre number, index number, name and class at the top of this page. 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 25 printed pages 1 blank page.

2 © DHS 2023 9744/01 1 Four students, A – D, were asked to match the function with the appearance of some cell structures in an animal cell. The functions were listed by a number. 1 mRNA passes through to the ribosome 2 organises microtubules to produce the spindle during cell division 3 packaging of hydrolytic enzymes that will remain in the cell The appearances were listed by a letter. V membranes which surround an enclosed inner cavity W non-membrane bound, spherical structures X a double membrane interspersed with pores Y non-membrane bound, cylindrical structures Z membrane-bound sacs, arranged as a flattened stack Which student correctly matched the numbered function with the appearance of the cell structure? 1 2 3 A V W Y B V Y Z C X W Y D X Y Z

3 © DHS 2023 9744/01 [Turn over 2 The electron micrograph shows a chloroplast. Which row correctly shows the function or characteristic of the labelled structure? help to maintain high H+ concentration made up of phospholipid where ATP is synthesised A 1 and 2 3 and 4 2 B 2 and 3 2 and 4 3 and 4 C 1 and 2 1, 2 and 3 3 and 4 D 3 and 4 1, 3 and 4 2 2 3 4 1

4 © DHS 2023 9744/01 3 Which row describes starch, glycogen, and cellulose? Starch Glycogen Cellulose A Highly branched amylose due to α-1,6 glycosidic bonds Highly compacted molecule that serves as a good energy storage in animal cells Provides structural support and prevents cells from bursting when turgid B Insoluble due to the – OH groups projecting into the interior of helices Made up of α-glucose monomers with 1,4 glycosidic bonds resulting in highly branched chains Cellulose chains are organised into microfibrils and macrofibrils C Can be easily hydrolysed to release α-glucose monomers Angle of α-1,4 bonds and CH2OH side chains results in helical chains Made up of long linear chains due to 180o rotation of alternate β-glucose D Highly compacted molecule that serves as a good energy storage in plant cells Made up of α-glucose monomers with 1,6 glycosidic bonds resulting in highly branched chains High tensile strength is due to the accumulative strength of the covalent cross linkages between cellulose chains 4 Which statements about glycosidic bonds are correct? 1 A hydroxyl group is formed on each molecule when a glycosidic bond is hydrolysed. 2 Only glycosidic bonds can be formed between glucose molecules. 3 The formation and breakage of glycosidic bonds are reversible. 4 The same enzymes are involved in the formation and breakage of glycosidic bonds. A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

5 © DHS 2023 9744/01 [Turn over 5 The diagram shows the structure of two lipid molecules. Which statements correctly describe the two lipid molecules? 1 Both molecules are esters of glycerol. 2 Both molecules are made by condensation reactions. 3 The hydrocarbon chains of molecule X are always from saturated fatty acids. 4 The hydrocarbon chains of molecule Y may be from saturated or unsaturated fatty acids. 5 The hydrocarbon chains of molecule Y are always the same length. A 1, 2 and 4 B 1, 3 and 5 C 2 and 4 D 3 and 5

6 © DHS 2023 9744/01 6 The diagram shows some interactions between amino acid R-groups in a polypeptide chain. Which row describes the nature of the interactions? can be disrupted by extreme pH can be disrupted by high temperatures located within the core of a globular protein located within the transmembrane domain of a membrane protein A 1, 3, 4 1, 2, 3, 4 2 1, 2, 4 B 1, 2, 4 3 1, 4 2, 3 C 3 1, 4 2, 3 1, 2, 3, 4 D 1, 4 1, 2, 4 2, 3 2, 3

7 © DHS 2023 9744/01 [Turn over 7 A student investigated the hydrolysis of lipids in high-fat milk, using the enzyme lipase. • 1 cm3 of enzyme solution was added to 10 cm3 of high-fat milk. • The temperature was kept constant. • The pH of the reaction mixture was recorded at 0 minutes and every minute for 20 minutes. Which statements could explain the possible results of the investigation? 1 Less product is made as time proceeds because the amount of substrate was decreasing. 2 The pH of the reaction mixture changed more rapidly in the first few minutes and then changed less rapidly. 3 The product gradually caused more lipase molecules to denature. A 1, 2 and 3 B 1 and 2 C 1 and 3 D 2 and 3

8 © DHS 2023 9744/01 8 Reindeers are well adapted to survive in extreme cold winters. One of these adaptations is having a unique cell membrane composition at different parts of its body. The graph show s the percentage composition of the components of cell membranes A and B taken from two different parts of the reindeer’s body. Which statement best explains the differences in the membrane composition in cell A and cell B? A Cholesterol decreases the membrane fluidity and prevents the membrane from breaking up by restraining the movement of phospholipids. B Cell membrane A is taken from a lower part of the reindeer’s leg as the unsaturated hydrocarbon tails will prevent the fatty acids from packing close to each other. C Cell membrane B is taken from a lower part of the reindeer’s leg as the saturated hydrocarbon tails will prevent the fatty acids from packing close to each other. D Transmembrane proteins maintain the osmotic balance between the interior and exterior of the cell, hence preventing the cell membrane from solidifying at low temperatures.

9 © DHS 2023 9744/01 [Turn over 9 The diagram shows part of a DNA molecule. How many hydrogen bonds are present in this diagram? A 6 B 8 C 10 D 12

10 © DHS 2023 9744/01 10 The mechanism of action of four drugs that inhibit DNA replication is stated below: • Drug 1 - inhibits the action of DNA ligase • Drug 2 - resembles the shape of a DNA nucleotide • Drug 3 - attaches irreversibly to the DNA molecule • Drug 4 - binds irreversibly to the active site of DNA polymerase Which row matches the drugs to their effects on DNA replication? Daughter strands of varying lengths are synthesized Only fragments are synthesised at the end of replication process Phosphodiester bonds cannot be formed Template strands become inaccessible by the enzyme. A 4 3 2 1 B 2 4 3 1 C 2 1 4 3 D 3 2 1 4