ACJC H2 Bio Prelim P1 compiled Ans

This paper consists of 19 printed pages. [Turn over Anglo-Chinese Junior College JC2 Biology Preliminary Examination Higher 2 BIOLOGY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet 9744/01 15 September 2023 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name and index number in the answer sheet 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. 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 Question Paper. The use of an approved calculator is expected, where appropriate.

2 Anglo-Chinese Junior College 2023 J2 H2 9744 Paper 1 Preliminary Examination 1 How many statements about the nucleus are correct? 1 The nucleolus comprises entirely of heterochromatic DNA. 2 The nuclear pores facilitate the separate movement of rRNA and ribosomal proteins out of the nucleus. 3 The nucleoplasm can only contain pre-mRNA and not mature mRNA. 4 The nuclear envelope will only disintegrate during apoptosis. 5 There will always be only one nucleolus per nucleus. A None B 1 C 2 D More than 2 AOA 2 Protozoans are single-celled eukaryotic organisms that can either be free-living or parasitic. Plasmodium falciparum, which causes the disease malaria, is an example of a parasitic protozoa. The diagram shows the basic cellular structure s of P. falciparum at a particular stage of its life cycle. Which features are shared between P. falciparum and typical bacterial cells? 1 presence of cell wall 2 able to carry out protein synthesis 3 energy production within cell 4 chromosome(s) found within nucleus 5 unicellularity A 1, 2, 3 and 5 B 1, 2 and 5 only C 1, 3 and 4 only D 2, 3 and 5 only Low AOB

3 [Turn over Anglo-Chinese Junior College 2023 J2 H2 9744 Paper 1 Preliminary Examination 3 Archaea are single-celled organisms. The phospholipids within the cell surface membrane of Archaea differ significantly from bacteria and eukaryotes. For instance, Archaeal phospholipids are composed of highly-methylated and saturated hydrocarbon chains that are connected to glycerol via ether bonds instead of ester bonds, and are therefore not prone to hydrolysis. Ethers are characterised by C -O-C linkages. The diagram shows the basic structure of phospholipids in Archaea, bacteria and eukaryotes. Many species of Archaea can survive in water and in environments with very harsh conditions such as high temperatures or strong acids. Which statement does not explain how the phospholipids within Archaea l cell surface membrane allow them to thrive in water or extreme conditions? A Methyl groups on the phospholipids enhance the blockage of water penetration through the membrane. B The presence of ether rather than ester bonds contributes to their chemical stability, particularly at high temperatures and extreme pH values. C Close packing of Archaea lipids confer low permeability of the cell surface membrane to protons hence there is very low proton influx in acidic conditions. D Archaea has a different glycerol backbone within the phospholipid structure hence making it structurally more stable under extremely high temperatures. High AOB

4 Anglo-Chinese Junior College 2023 J2 H2 9744 Paper 1 Preliminary Examination 4 Which row correctly matches the structural properties to the biomolecules? α-1,4-glycosidic bonds β-1,4-glycosidic bonds branched structure interchain H-bonds A cellulose amylopectin glycogen amylose B amylopectin cellulose amylose cellulose C glycogen amylose amylopectin cellulose D amylose cellulose amylopectin amylose AOA 5 Scurvy is a disease caused by vitamin C deficiency. Left untreated, scurvy can result in bleeding gums, loosened teeth and bleeding under the skin. Treatment for the condition includes significantly increasing the intake of vitamin C in the diet. Vitamin C is the essential cofactor for two enzymes, prolyl hydroxylase and lysyl hydroxylase, which are required for collagen synthesis. These enzymes catalyse the hydroxylation of proline and lysine residues of procollagen. Which statement best explains why vitamin C deficiency can lead to scurvy? A Active sites of prolyl hydroxylases and lysyl hydroxylases will not be complementary to their substrates. B There would not be sufficient vitamin C to catalyse the hydroxylation of proline and lysine residues. C Hydroxylation of all residues are important as it markedly increase the conformational stability of the collagen triple helix. D Lack of hydroxylation of residues on collagen affects the stability of tropocollagen and the proper formation of collagen fibrils. Low AOB

5 [Turn over Anglo-Chinese Junior College 2023 J2 H2 9744 Paper 1 Preliminary Examination 6 Catalase, an enzyme produced by liver tissue, breaks down hydrogen peroxide into water and oxygen. To investigate the effects of changing hydrogen peroxide concentration on the rate of oxygen production, small cubes of fresh liver tissue w ere added to hy drogen peroxide solutions of different concentrations. The volume of oxygen produced per unit time from each reaction was recorded and the data was shown in a graph. Which statement is correct? A At P, the rate of reaction is limited by the concentration of the substrate. B At R, all the catalase active sites are saturated. C At S, the enzyme concentration is the limiting factor. D At Q, half the total volume of oxygen is collected from the reaction. Low AOB 7 The graph shows the activity of enzymes E, F and G under different pH conditions. Which statement is not a valid conclusion of these enzymes? A The affinity between substrate and enzyme E is highest when the pH is 2.5. B At pH 6.2, the kinetic energy of enzymes F and their substrates is the highest. C Ionic and hydrogen bonds in enzyme E are affected when pH changes. D Rate of reactions catalysed by enzyme F is higher than those catalysed by enzyme E and G at pH 6. Low AOB rate of oxygen production/ cm3 min-1

6 Anglo-Chinese Junior College 2023 J2 H2 9744 Paper 1 Preliminary Examination 8 Type 1 and type 2 diabetes are both characterised by higher -than-normal concentrations of blood glucose. In type 1 diabetes, the β cells produce little or no insulin. In many cases of type 2 diabetes, insulin is produced normally but does not bind to the insulin receptor s of the cells around the body. This is termed insulin resistance. Hence, glucose in the blood is not taken up by cells for cellular activities. Recent experiments suggest that it may, in future, be possible to treat diabetes with adult stem cells from the patient’s own bone marrow. However, such an approach is more suitable for treating type 1 rather than type 2 diabetes. Which statement could explain why stem cell treatment will not work well for type 2 diabetes? A An overproduction of glucagon could happen as the stem cells differentiate to form α cells instead due to plasticity. B Cells in the body have dysfunctional insulin receptors hence it is more difficult to replace all of them.