HCI 2023 JC2 9744 H2 Bio Prelim P1 QP (Sharing)

© Hwa Chong Institution 2023 9744 H2 Biology / JC2 Preliminary Examinations / Paper 1 HWA CHONG INSTITUTION JC2 Preliminary Examinations Higher 2 CANDIDATE NAME CT GROUP 22S7___ CENTRE NUMBER INDEX NUMBER BIOLOGY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet 9744/01 20 September 2023 1 hour INSTRUCTIONS TO CANDIDATES 1. Write your name, CT group, Centre number and index number in the spaces provided at the top of this cover page. 2. Fill in your particulars on the Multiple Choice Answer Sheet. Write your NRIC number and shade accordingly. 3. 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. 4. At the end of the paper, you are to submit only the Answer Sheet. INFORMATION FOR CANDIDATES 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 used of an approved scientific calculator is expected, where appropriate. This document consists of 24 printed pages.

2 © Hwa Chong Institution 2023 9744 H2 Biology / JC2 Preliminary Examinations / Paper 1 1 Clostridium tetani is the bacterium that causes the disease tetanus. Symptoms of the disease are caused by the release of a toxin, tetanospasmin. The diagram shows a transmission electronmicrograph of cells of Clostridium tetani. Which visible features suggest it is a prokaryote and not a eukaryote? 1 The presence of a cell wall surrounding the cell that is oval in shape. 2 The nucleoid region is not enclosed by a nuclear envelope. 3 The lack of membranous organelles within the cell. 4 The presence of 70S ribosomes that covered the cisternae of rough endoplasmic reticulum. A 1 and 2 only B 1 and 4 only C 1, 2 and 3 only D 2 and 3 only

3 © Hwa Chong Institution 2023 9744 H2 Biology / JC2 Preliminary Examinations / Paper 1 2 Four students were asked to match the function with the appearance of some cell structures in an animal cell. The functions were listed by number. 1 mRNA passes through to the ribosome 2 produces the mitotic spindle during cell division 3 packaging of hydrolytic enzymes that will remain in the cell The appearances were listed by letter. V membranes which surround an enclosed inner cavity W non-membrane-bound, spherical structures X a double membrane interspersed with pores Y non-membrane-bound, cylindrical structures Z membrane-bound sacs, arranged as a flattened stack Which student correctly matched the numbered function with the appearance of the cell structure? 1 2 3 A V W Y B V Y Z C X W Y D X Y Z

4 © Hwa Chong Institution 2023 9744 H2 Biology / JC2 Preliminary Examinations / Paper 1 3 The diagram shows the structure of the cell membrane with molecules labelled 1 to 6. Which row correctly matches the molecules with its role? contributes to fluidity of the cell membrane contributes to cell recognition contributes to stability of the cell membrane contributes to movement of solutes across the cell membrane A 1 3, 5 2, 4 6 B 1 4, 5 3, 6 2 C 2 4, 6 3, 6 1 D 2 3, 6 1, 4 3 4 The pandoraviruses are the largest known viruses to be discovered. Some of its features are listed. 1 Its genome is double-stranded DNA consisting of over 2 million nucleotide pairs. 2 It is able to replicate only within an amoeba. 3 It causes pneumonia in humans. Which features suggest that pandoraviruses are viruses? A 1 only B 2 only C 1 and 3 only D 1, 2 and 3 4 5 6 2 1 3 1 2 3 4 5 6

5 © Hwa Chong Institution 2023 9744 H2 Biology / JC2 Preliminary Examinations / Paper 1 5 Olestra is an artificial lipid . It is made by attaching fatty acids, by condensation, to a sucrose molecule. A simplified diagram of olestra is shown. R represents the position where fatty acids would be attached. Humans cannot hydrolyse olestra. However, other animals may be able to do so. How many molecules of water would be needed to hydrolyse one molecule of olestra into fatty acids, fructose and glucose? A 11 B 10 C 9 D 8 6 Insulin is a globular protein involved in cell signalling. It is transported in the blood plasma from the cells that synthesise it to its target cells. A molecule of insulin contains six sulfur- containing amino acids and has two polypeptide chains. Which statements about insulin are correct? 1 An insulin molecule has a quaternary structure. 2 Insulin polypeptides are held together by six disulfide bonds. 3 Amino acid residues with non-polar R groups would be found in the centre of an insulin molecule. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

7 The end-product of a metabolic pathway can act as a competitive inhibitor. This is called end- product inhibition and allows a cell to control a metabolic pathway. The diagram shows a metabolic pathway where the end-product could act as an inhibitor of enzyme W. What would be the effect if enzyme Z was inhibited by the end-product instead of enzyme W? quantity of intermediate 1 quantity of intermediate 3 quantity of end-product A increase increase decrease B increase decrease unchanged C decrease increase decrease D decrease decrease unchanged

8 The diagram shows how embryonic stem cells are produced in therapeutic cloning for use in patients. Which statements are possible ethical considerations of using such embryonic stem cells? 1 A potential life is being destroyed. 2 Embryonic stem cells are pluripotent in nature. 3 These embryonic stem cells can produce cells of any type. 4 These embryonic stem cells contain both the patient’s nuclear genome and the donor’s mitochondrial genome. A 1 and 2 only B 1 and 4 only C 3 and 4 only D 1, 3 and 4 only patient donor cell donor egg cell nuclear transfer nucleus removed blastocyst – a group of about 100 cells embryonic stem cells used to treat disease

9 Bacteria were cultured in the presence of 15N for several generations, until most of the natural 14N atoms in their DNA were replaced by the 15N isotope. A large excess of 14N was then added to the culture and samples were taken immediately after the addition, as well as 20 min and 40 min later. Cell extracts of the samples were subjected to caesium chloride density -gradient centrifugation. The diagram s hows three distinct DNA bands. The amount of DNA in each band was determined by absorbance of UV light at 260 nm and are represented by peaks P, Q and R. A260 immediately after addition A260 20 min after addition A260 40 min after addition Which statement correctly characterises the DNA molecules of the three peaks? A Peak P DNA contains mostly 14N B Peak Q DNA contains approximately equal amounts of 14N and 15N C Peak R DNA contains mostly 15N D Peak R DNA contains approximately equal amounts of 14N and 15N P Q Q R

10 The electronmicrograph shows simultaneous transcription and translation of a single gene in the bacterium Escherichia coli. Which row is correct? polarity of X at arrow X Y Z A 3’ DNA RNA polymerase mRNA B 3’ DNA ribosome mRNA C 5’ DNA ribosome polypeptide D 5’ mRNA ribosome polypeptide 11 The table shows a comparison of some aspects of the genomes of eukaryot es and prokaryotes. organism complexity estimated genome size (base pairs) estimated number of genes gene density (genes/Mb) Human 3 billion 25,000 6.5 Mouse 2.9 billion 30,000 10 Fruit fly 165 million 14