TMJC 2023 H2 P1 Ans

CANDIDATE NAME ( ) CIVICS GROUP H2 BIOLOGY 9744/01 Paper 1 Multiple Choice Questions 22 September 2023 1 hour Additional material: Multiple Choice Answer Sheet ANSWERS WITH EXPLANATION QUESTION ANSWER QUESTION ANSWER 1 C 16 B 2 C 17 C 3 A 18 D 4 A 19 C 5 D 20 D 6 B 21 C 7 D 22 A 8 A 23 B 9 A 24 A 10 A 25 B 11 A 26 D 12 D 27 B 13 A 28 D 14 D 29 C 15 C 30 B ________________________________________________________________________________ This document consists of 19 printed pages. TAMPINES MERIDIAN JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION

2 Tampines Meridian Junior College 2023 JC2 Preliminary Examination H2 Biology QUESTION 1 [Cell, HI-1] The photomicrograph is of a plant cell. The cell is 25 µm in width from X to Y. What is the magnification of the photomicrograph? A 2 x 101 B 2 x 102 C 2 x 103 D 2 x 104 Explanation Length of drawing of cell = 5cm = 50mm = 50 000 µm Magnification= Length of drawing/actual length = 50 000 / 25 = 2000 = 2 x 103

3 Tampines Meridian Junior College 2023 JC2 Preliminary Examination H2 Biology QUESTION 2 [Cell, HI-2] The diagrams below show the electron micrographs of two organelles P and Q. Which of the following shows the correct identities and functions of P and Q? Identity of P Function of P Identity of Q Function of Q A Nucleosome Transcription of rRNA gene Smooth ER Transport of proteins B Nucleosome Assembly of ribosomal subunits Secretory vesicles Synthesis of lipids C Nucleolus Assembly of ribosomal subunits Smooth ER Synthesis of lipids D Nucleolus Transcription of rRNA gene Secretory vesicles Transport of proteins

4 Tampines Meridian Junior College 2023 JC2 Preliminary Examination H2 Biology QUESTION 3 [Cell, KU-2] Which letter identifies the cell structures where semi-conservative replication of DNA occurs? (A) Explanation: All 3 organelles (chloroplast, mitochondria and nuclei) contain DNA and DNA polymerase which allow DNA replication to occur. QUESTION 4 [Transport, HI-2] The chart shows the concentration of some substances outside the cell, in the cytoplasm, in the chloroplast and in the Golgi body 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 ATP is leaving the chloroplast by facilitated diffusion, water is leaving the plant cell by osmosis. B Phosphate and ATP are entering the chloroplast and Golgi body by active transport. C Phosphate and ATP are leaving the Golgi body by facilitated diffusion, water is leaving the plant cell by osmosis. D Phosphate is entering the chloroplast by facilitated diffusion, water is entering the chloroplast by osmosis. Explanation: Statement B: Both ATP and phosphate Concentration are lower in Golgi body compared to the cytoplasm, hence they cannot be entering GA via active transport. Statement C: Both ATP and phosphate Concentration are lower in Golgi body compared to the cytoplasm, hence they cannot leaving GA via facilitated diffusion. Statement D: Phosphate concentration is higher in chloroplast compared to cytoplasm, hence it enters the chloroplast via active transport.

5 Tampines Meridian Junior College 2023 JC2 Preliminary Examination H2 Biology QUESTION 5 [BioMol, HI-2] The diagram shows some interactions between amino acid R-groups in a polypeptide chain. Which row correctly 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 receptor protein A 1, 3, 4 1, 2, 3, 4 2 1, 2, 4 B 2, 4 3 1, 4 2, 3 C 3 1, 4 2, 3 1, 2, 3, 4 D 1, 4 1, 4 2, 3 2 Explanation 1. Hydrogen bond 2. Hydrophobic interaction 3. Disulfide bond 4. Ionic bond • Extreme pH and high temperature disrupt both hydrogen bond and ionic bond which are weak bonds. • Globular protein has hydrophilic amino acids on the outside and hydrophobic amino acids within the core, hence both hydrophobic interactions and disulfide bonds are found within the core. Transmembrane domain of the receptor protein interacts with the hydrophobic fatty acid chain of the phospholipid bilayer, hence the hydrophobic amino acids are found at the transmembrane

6 Tampines Meridian Junior College 2023 JC2 Preliminary Examination H2 Biology QUESTION 6 [BioMol, KU-2] How many of the following statements correctly describe red blood cells? • At high altitude, humans have increased number of red blood cells to compensate for low percentage saturation of oxygen. • At high altitude, humans have increased number of red blood cells to increase the number of mitochondria in the blood for ATP production. • The shape of haemoglobin in red blood cells changes when oxygen is released from it. • Haemoglobin in red blood cells is insoluble in water because hydrophobic R groups are arranged around the outside of the molecule. A 1 B 2 C 3 D 4 Explanation Statement 1 & 3 are correct. Statement 2: Red blood cell do not have organelles such as mitochondria. Statement 4: Haemoglobin is a globular protein which is soluble in water with hydrophilic R groups arranged on the outside of the molecule. QUESTION 7 [BioMol, KU-1] Collagen is a fibrous protein found in mammalian tendons. Which feature contributes to the great tensile strength of collagen? A A secondary structure with many hydrogen bonds firmly holding the α-helices. B A regularly folded tertiary structure held together with hydrogen bonds and ionic bonds. C A primary sequence with covalent bonds linking a variable sequence of amino acids. D A quaternary structure of triple heli x held together by hydrogen bonds between the three polypeptides. Explanation Option A: Each collagen polypeptide chain consists of about 1000 amino acid residues and is in the shape of a loosely wound left-handed helix (NOT an α-helix). Option B: It is a fibrous protein with a quaternary structure. It has no tertiary structure. Three polypeptide chains are wound around each other to give a triple helix known as tropocollagen. Option C: This statement is factually correct but it does not contribute to its great tensile strength. Sequence of amino acids is usually a repeat of: o Glycine − Proline − X, or o Glycine − X − Hydroxyproline [where X is any other amino acids except glycine] Option D: The three polypeptide chains in the triple helix are linked together by hydrogen bonds formed between peptide N-H groups of glycine and peptide C=O groups of other amino acids on the other chains.

7 Tampines Meridian Junior College 2023 JC2 Preliminary Examination H2 Biology QUESTION 8 [Enzymes KU-2] The lock-and-key hypothesis and induced-fit hypothesis explain how an enzyme interacts with a substrate. Which of the following statements are true of both hypotheses? 1 An increase in substrate concentration will not increase the rate of formation of enzyme - substrate complexes. 2 Covalent bonds hold the substrate at the active site of the enzyme. 3 An enzyme undergoes a conformational change as it forms enzyme-substrate complexes. 4 An increase in enzyme concen