2022 EJC Promo JC1 P1 Bio (A)

©EJC 2022 9744/01/J1H2PROMO/2022 [Turn over EUNOIA JUNIOR COLLEGE JC1 Promotional Examinations 2022 General Certificate of Education Advanced Level Higher 2 H2 Biology Paper 1 9744 / 01 04 October 2022 1 hour Additional Materials: Optical Mark Sheet READ THESE INSTRUCTIONS FIRST You have a total of 1 hour to attempt this paper. Write your name, civics group and registration number on all the work you hand in. There are thirty 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 Optical Mark Sheet. The use of an approved scientific calculator is expected, where appropriate. Answer all questions. This document consists of 19 printed pages and 1 blank page.

2 ©EJC 2022 9744/01/J1H2PROMO/2022 Answer all questions on the Optical Mark Sheet provided. 1 Dextrins a re a group of carbohydrates with low molecular weight and are produced by hydrolysing starch or glycogen. Which of the following segments is/are not likely to be from a dextrin molecule? 1 2 3 4 A 1 only B 1 and 4 only C 1, 2 and 3 only D 2, 3 and 4 only

3 ©EJC 2022 9744/01/J1H2PROMO/2022 [Turn over 2 The diagram below shows a repeating unit found in a biomolecule. Which of the following biomolecules has the above repeating unit? cellulose glycogen amylose collagen A X X √ X B √ X √ X C √ X X √ D X √ √ X 3 The structure of phosphatidylcholine, a common membrane phospholipid, is shown. Which combination correctly describes the synthesis and property of one molecule of phosphatidylcholine? number of water molecules eliminated during synthesis property A 3 amphipathic B 2 amphipathic C 3 hydrophobic D 2 hydrophobic

4 ©EJC 2022 9744/01/J1H2PROMO/2022 4 A peptide section of an insulin molecule was hydrolysed by two proteases, trypsin and chymotrypsin. • Trypsin breaks the peptide bonds at the carboxyl terminals of lysine (lys) and arginine (arg). • Chymotrypsin breaks the peptide bonds at the carboxyl terminals of phenylalanine (phe), tryptophan (trp) and tyrosine (tyr). The hydrolysis was performed separately using: 1 both enzymes, or 2 trypsin only, or 3 chymotrypsin only. The sequence of amino acid residues in the peptide is shown below: tyr-leu-val-cys-gly-glu-arg-gly-phe-phe-tyr-thr-pro-lys-ala Which statement concerning the products of hydrolysis is correct? A Fewer than half of the fragments from hydrolysis 1 are single amino acids. B Hydrolysis 2 yields one fewer fragment than hydrolysis 3 C Hydrolysis 2 yields one more dipeptide than hydrolysis 3 D With hydrolysis 1, all fragments formed are seven or fewer amino acid residues long. 5 An electron micrograph of a stained fibre of deoxyhaemoglobin S (HbS) is shown below. Which of the following statements is true? A Mutation in the mature red blood cell results in the production of HbS which precipitates out as long rigid fibres 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 aggregation of HbS molecules, under low oxygen concentration, causes the fibre to be precipitated out of solution, resulting in the sickling of red blood cells. D Under low oxygen concentration, HbS molecules form a triple helix structure, causing the cell membrane of the red blood cells to be more rigid and hence this results in sickling of red blood cells. amino terminal carboxyl terminal

5 ©EJC 2022 9744/01/J1H2PROMO/2022 [Turn over 6 The electron micrograph below shows three cell organelles W, X and Y. Which of the following statements about these organelles is true? A Only organelle X 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. organelle W organelle X organelle Y

6 ©EJC 2022 9744/01/J1H2PROMO/2022 7 The following electron micrograph shows root cells from the duckweed plant. Which of the following about structures 1 to 5 is correct? contain ribosomal subunits contain tRNA contain phospholipids A 1, 2, 3 3 only 1, 4 B 1, 3, 4 1, 3 2, 5 C 1, 3, 5 1, 2, 4 2, 4, 5 D 2, 4, 5 2, 4, 5 1, 3, 4, 5 8 Which set of factors shown below will result in the cell surface membrane being the least fluid? A High proportion of cholesterol and high temperature B Low proportion of phospholipids with saturated fatty acids and high temperature C Low proportion of phospholipids with unsaturated fatty acids and low temperature D High proportion of phospholipids with unsaturated fatty acid and low temperature 1 2 3 4 5

7 ©EJC 2022 9744/01/J1H2PROMO/2022 [Turn over 9 The diagram shows the relationship between the size, lipid solubility and ability of molecules to cross the mammalian cell surface membrane. The diameter of the black circles in the diagram is proportional to the size of the molecules. Which of the following could molecules W to Z represent? W X Y Z A glucose water carbon dioxide cholesterol B glucose methane carbon dioxide calcium chloride C calcium chloride methane cholesterol glucose D calcium chloride water glucose cholesterol 10 Serine proteases, such as chymotrypsin and trypsin, are enzymes that cleave peptide bonds in proteins. Three specific amino acids (Asp, His, Ser) arranged in a special alignment, are found conserved in all serine proteases. This conserved alignment is often referred to as "the catalytic triad". At the active site, scientists also found a variable region between different members in this class of enzymes. Which feature allows different serine proteases to bind to different substrates? A Presence of a specific cofactor required for catalysis B Specific spatial arrangement of Asp, His, and Ser at the active site C Different R-group properties of amino acids in the catalytic triad D Different R-group properties of amino acids lining the variable region

8 ©EJC 2022 9744/01/J1H2PROMO/2022 11 In the production of isoleucine from threonine, the end product acts as an inhibitor of the first enzyme of the pathway. The pathway is shown below. Which of the following graphs shows the concentration of intermediate Y when threonine is supplied in excess? A B C D

9 ©EJC 2022 9744/01/J1H2PROMO/2022 [Turn over 12 The structures of some drugs that are analogues of viral nucleotides are shown below. They interfere with viral nucleic acid synthesis so that incomplete polynucleotides are formed. acyclovir gancyclovir Which statement explains how these drugs interfere with viral nucleic acid synthesis? A They are competitive inhibitors of DNA or RNA polymerase enzymes. B They bind irreversibly to the active site of the viral DNA or RNA polymerase. C They bind irreversibly to the active site of the host cell DNA or RNA polymerases. D They replace nucleotides so inactive nucleic acids are synthesised instead of active ones. 13 Four nucleotides, A, B, C and D, each consist of a phosphate group, a nitrogenous base, and a pentose sugar. Characteristics of the base and sugar components before they are joined to form each nucleotide are shown in the table. Which nucleotide could pair with an adenine base during DNA replication? ring structure of nitrogenous base ratio of carbon to oxygen atoms in pentose sugar A single 1:1 B single 5:4 C double 1:1 D double 5:4