2024 TJC H2 Bio P1 QP

1 [Turn over TEMASEK JUNIOR COLLEGE 2024 JC2 PRELIMINARY EXAMINATION Higher 2 BIOLOGY 9744/01 Paper 1 Multiple Choice 12 September 2024 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, civics group and index number on the Answer Sheet in the spaces provided. Do not open this booklet until you are told to do so. 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 20 printed pages and 0 blank page.

2 1 The flow chart show processes which take place inside animal cells. Which processes require the activity of lysosomes A W and X only B X and Y only C Y and Z only D W, X, Y and Z

3 [Turn over 2 A scientist carried out an experiment to separate the organelles in an animal cell by mass. The scientist mixed the cells with a buffer solution which had the same water potential as the cells. The cells were broken open with a blender to release the organelles. The extracted mixture was filtered and then spun in a centrifuge at a high speed to separate the heaviest type of organelle. These sank to the bottom, forming solid pellet 1. The liquid above pellet 1 was poured into a clean centrifuge tube and spun in the centri fuge at a higher speed to separate the next heaviest type of organelle. These organelles sank to the bottom, forming solid pellet 2. This procedure was repeated twice more to obtain pellet 3 and pellet 4, each containing a single organelle. What is the main function of the type of organelle extracted in pellet 2? A digestion of old organelles B production of ATP C production of mRMA D synthesis of protein 3 The three main factors that affect the rate of diffusion across a membrane can be expressed by the relationship shown. Which changes in the factors would result in the rate of diffusion doubling? 1 surface area has doubled. 2 concentration difference has halved. 3 thickness of the membrane has doubled. 4 Thickness of the membrane has halved. A 1, 2 and 4 B 1 and 3 C 1 and 4 D 2 and 3

4 4 The diagram shows the relationshi p between different polysaccha rides and glycosidic bonds formed between the monomers. Which row is correct? 1 2 3 4 5 A Amylopectin α 1,6 Cell ulose β 1,4 Glycogen B Amylose α 1,4 Glycogen β 1,4 Amylopectin C Cellulose β 1,4 Amylose α 1,4 Glycogen D Glycogen α 1,6 Amylopectin α 1,4 Amylose 5 The diagram shows three triglycerides, X, Y and Z. Which row is correct for these triglycerides? 1 2 3 4 5

5 [Turn over contains saturated fatty acids contains unsaturated fatty acids contains more than two different fatty acids A X, Y and Z X and Y X and Y B X, Y and Z Z X and Y C X and Y X, Y and Z X, Y and Z D Z X and Y X, Y and Z 6 CYP3A4 is an important enzyme in the human digestive system whe re it is needed to break down a range of different toxins. The activity of CYP3A4 has be en shown to be reduced by substances called furanocoumarins. Furanocoumarins are found in some fruits and so dangerous conce ntrations of toxins may develop in the human digestive system when fruits containing furanocoumarins are eaten From the information provided, what can be concluded about molecules of the enzyme CYP3A4? A They lower the activation energy of the toxin breakdown reactions. B They bind specifically through the active site to a substrate found in some fruits. C They change permanently when acted upon by furanocoumarin molecules. D They resume normal activity when concentrations of furanocoumarins decrease.

6 7 A fixed volume and concentration of substrate and enzyme were mixed. All other variables were kept constant. The enzyme-catalyzed reaction was allowed t o proceed until it was completed. Which graph shows how the rate of reaction changes with time? C 8 The table shows the percentages of nitrogenous bases in four samples of nucleic acids. Which base is adenine? Sample Bases A B C D Uracil 1 31 19 19 30 Nil 2 23 27 26 24 Nil 3 25 25 25 Nil 25 4 32 17 18 33 Nil

7 [Turn over 9 The active messenger RNAs (active mRNAs) in tissue cells can be isolated by passing the homogenized cell contents through a fractionating column. The c olumn has short lengths of uracils nucleotides attached to a solid supporting material. Mo st molecules of mRNA that pass through the column quickly break up into small pieces and cannot be translated. The active mRNAs that attach to the column can be separated again by appropriate treatment. Which statements correctly describe active mRNA? 1 Active mRNAs can be held to the fractionating column by bonds between adenine and uracil bases. 2 Active mRNAs can be released from the fractionating column by breaking hydrogen bonds. 3 Only mRNAs with polyadenine tailing can be translated. 4 Polyadenine tailing stabilizes mRNA and prevents it from being broken up. A 1 and 2 only B 1, 2 and 3 C 3 and 4 only D All of the above 10 IPTG in an analogue of lactose that binds to the lac repressor in the same fashion as allolactose. However, it cannot be metabolized by β-galactosidase. Escherichia cells, which were gr own in the absence of lactose a nd glucose, were initially supplemented with IPTG. After 10 minutes, glucose was added to the cells. 10 minutes after glucose was added, cAMP was added to the cells. Which of the following graphs best represents how the concentration of the lac operon mRNA varied during the experiment? B

8 11 Which of the following pairs of statements is not true of generalized and specialized transduction? Generalized Specialized 1 Transfers any bacterial DNA Transfers a specific set of bacterial genes 2 Contains a hybrid chromosome in its capsid Contains only bacterial chromosome in its capsid 3 Viral DNA is transcribed in the recipient cell Viral DNA is not transcribed in the recipient cell 4 Viral DNA is integrated into the host chromosome Viral DNA is not integrated into the host chromosome 5 Viral DNA is not replicated by binary fission of the recipient cell Viral DNA is replicated by binary fission of the recipient cell A 1, 4 and 5 B 2, 4 and 5 C 3, 4 and 5 D 2, 3 and 4 12 Which of the following statements about the reproductive cycle of the Human Immunodeficiency virus are false? 1 The HIV particles recognize the host cell through the sialic- acid containing proteins or lipids on the membrane of the host cell. 2 The genome of HIV consists of 2 copies of linear, single-stra nded RNA enclosed in a nucleocapsid. 3 The viral DNA which enters the host cell’s nucleus will be in tegrated into the genetic material of the host cell using the host cell’s enzyme, integrase. 4 The viruses are released from the host cell by exocytosis. A 1, 2, 3 and 4 B 1, 3 and 4 C 2 and 4 D 1 and 3 13 Which of the following are properties of enhancers? 1 They are located away from the gene they control. 2 They are protein factors binding to regulatory regions of the DNA. 3 They increase t