JPJC 2023 J2 H2 BI Prelim P1 QP

9744 / 01 [Turn over NAME: CLASS: JURONG PIONEER JUNIOR COLLEGE JC2 Preliminary Examination 2023 BIOLOGY Higher 2 9744/01 19 September 2023 Paper 1 Multiple Choice 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, class and index number on the Answer Sheet in the spaces provided unless this has been done for you. 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 17 printed pages and 3 blank pages.

2 JPJC/JC2 H2 Biology/Prelims/2023 1 A molecule of carbon dioxide is in the centre of a mitochondrion. Assuming there are no other cell structures in its path, how many phospholipid layers will the carbon dioxide molecule have to pass through to leave the cell? 9700_s20_qp_13 A 2 B 3 C 4 D 6 2 Which nitrogenous bases are present in all viruses? 1 thymine 2 adenine 3 cytosine A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only 3 The enzyme α-amylase hydrolyses amylopectin but it is not able to hydrolyse some of its glycosidic bonds. • It only hydrolyses 1,4 glycosidic bonds. • It is not able to hydrolyse the last bond of a chain. • It is not able to hydrolyse the bonds in a chain of three units attached by a 1,6 glycosidic bond to another chain. Which glycosidic bond can be hydrolysed by α-amylase?

3 JPJC/JC2 H2 Biology/Prelims/2023 [Turn over 4 When investigating the rate of reaction of the enzyme lipase on the hydrolysis of triglycerides, the pH must be maintained at an optimum to prevent the lipase denaturing. What is the reason for this? A The addition of water molecules produced by hydrolysis increases pH. B The products of hydrolysis decrease the pH. C The products of hydrolysis increase the pH. D The removal of water molecules used in hydrolysis decreases pH. 5 Four mechanisms involved in the movement of substances across membranes are shown below. Which features of these transport mechanisms are represented by P, Q and R? P Q R A involves membrane carrier proteins passive movement movement against a concentration gradient B involves membrane transport proteins movement down a concentration gradient passive movement C movement against a concentration gradient involves membrane channel proteins movement through the hydrophobic core of the phospholipid bilayer D requires energy supplied by ATP movement through the hydrophobic core of the phospholipid bilayer involves membrane channel proteins

4 JPJC/JC2 H2 Biology/Prelims/2023 6 The diagram shows three interactions that hold protein molecules in shape. Which row identifies these interactions? interaction 1 interaction 2 interaction 3 A hydrogen bond disulfide bond hydrophobic interaction B hydrogen bond covalent bond ionic bond C hydrophobic interaction ionic bond hydrogen bond D ionic bond disulfide bond peptide bond 7 Some animals produce antimicrobial proteins which protect them from pathogens. These proteins could be used to kill human pathogens, however when used as a medicine they are broken down by protein-digesting enzymes. Replacing one of the amino acids found in the protein with an amino acid that had been synthesised in the laboratory resulted in a modified protein that was not broken down. What could explain why this modified protein was not broken down by the protein-digesting enzymes? 1 The modified protein has a different tertiary structure to the original protein. 2 The modified protein is not complementary in shape to the enzyme’s active site. 3 The modified protein is unable to induce a fit with the protein-digesting enzyme. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

5 JPJC/JC2 H2 Biology/Prelims/2023 [Turn over 8 Which row describes some properties of stem cells? able to divide by mitosis to produce more stem cells able to differentiate into specialised cells able to repair damaged cells A    key = is a property  = is not a property B    C    D    9 How many statements about semi-conservative replication of DNA in a eukaryotic cell are correct? 1 The process takes place in the cytoplasm. 2 An adenine nucleotide will line up against uracil on the template strand. 3 Each daughter molecule will contain half of the original DNA molecule. 4 If the DNA molecule contained 40% guanine nucleotides, each daughter molecule will contain 20% guanine nucleotides. A 1 B 2 C 3 D 4 10 Some viruses are able to bind to the cell surface membrane before entering the host cell. Which sequence of events will lead to a virus invading a cell? A binding to a cholesterol molecule, followed by endocytosis B binding to a glycoprotein receptor, followed by exocytosis C binding to a protein receptor, followed by endocytosis D binding to the hydrophilic portion of a phospholipid, followed by exocytosis

6 JPJC/JC2 H2 Biology/Prelims/2023 11 Two mutant strains of Escherichia coli, one having the F-plasmid and the other without the F-plasmid were mixed in suspension. One was unable to synthesise biotin and the amino acid threonine, the other was unable to manufacture the two amino acids leucine and lysine. The genes coding for the synthesis of these essential metabolites are widely separated on the F-plasmid. After sixty minutes the bacteria were plated onto a growth medium deficient in all four metabolites. Four hundred colonies grew. Which process would result in bacteria that are able to grow on a growth medium deficient in these essential metabolites? A conjugation B translocation C transduction D transformation 12 Gibberellin is a plant hormone which stimulates seed germination by the following mechanism: 1 PIF is required to stimulate the synthesis of amylase. 2 DELLA is a protein attached to PIF. 3 When gibberellin is present it binds to a receptor and an enzyme. 4 This complex breaks down the DELLA protein. 5 PIF is released. 6 PIF binds to the promoter region on the amylase gene. 7 Transcription of amylase begins. 8 Amylase enzyme is responsible for the initiation of seed germination. What role do the regulatory components DELLA and PIF play in the described mechanism? DELLA PIF A promoter of amylase activator protein B repressor protein promoter of amylase C repressor protein transcription factor D transcription factor transcription factor

7 JPJC/JC2 H2 Biology/Prelims/2023 [Turn over 13 A piece of DNA is cut into fragments using the restriction enzymes Bam HI and EcoRI at the sites indicated in the diagram below. How many bands would be observed following separation of the fragments by electrophoresis? A 3 B 5 C 6 D 10

8 JPJC/JC2 H2 Biology/Prelims/2023 14 The DNA triplets of genes are translated as amino acids or stop signals during protein synthesis. The table shows some of these triplets. What could be the effects of one substitution mutation in a triplet coding for tyrosine? 1 The triplet is translated as cysteine. 2 The triplet is translated as tryptophan. 3 The triplet is translated as tyrosine. 4 Translation stops at this triplet. A 1, 2 and 3 B 1, 2 and 4 C 1, 3 and 4 D 2, 3 and 4

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