2022 HCI JC2 H2 Biology Prelims Paper 3 QP

© Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 HWA CHONG INSTITUTION JC2 Preliminary Examinations Higher 2 CANDIDATE NAME CT GROUP 21S7 ___ CENTRE NUMBER INDEX NUMBER BIOLOGY Paper 3 Long Structured and Free-response Questions Candidates answer on the Question Paper. No Additional Materials are required. 9744/03 13 September 2022 2 hours INSTRUCTIONS TO CANDIDATES Write your name, CT group, Centre number and index number in the spaces at the top of this cover page. Section A Answer all questions in the spaces provided on the Question Paper. Section B Answer any one question in the spaces provided on the Question Paper. INFORMATION FOR CANDIDATES The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. The number of marks is given in brackets [ ] at the end of each question or part question. You are reminded of the need for good English and clear presentation in your answers. This document consists of 20 printed pages. For Examiners' Use 1 / 30 2 / 10 3 / 10 4 or 5 / 25 Total / 75

2 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 BOOKLET I SECTION A Answer all the questions in this section. QUESTION 1 Tropical cone snails are small, slow -moving marine animals. They are carnivores, which hunt and kill prey that include fish. Fig. 1.1 shows two different hunting behaviours exhibited by cone snails. Both hunting behaviours use conotoxins that are made up of a cocktail of different types of proteins. The hunting behaviours include: ● taser-and-tether (TT), where electricity and conotoxins are discharged resulting in instantaneous immobilization of prey ● net-engulfment (NE), where a cloud of conotoxins is released to stun nearby fish and the muscular walls of the rostrum (false mouth) extends out to form a massive funnel to engulf multiple prey fish. taser-and-tether (TT) net engulfment (NE) Fig. 1.1

3 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 (a) Suggest and explain which hunting method is more efficient. [3] The conotoxins bind to the membrane -bound receptors on the muscle cells in fish to immobilise them. (b) Suggest how a cocktail of proteins instead of a single protein is advantageous for the cone snail. [3] Insulin and ρ-TIA are two types of proteins commonly found in conotoxins. (c) Describe how insulin is able to trigger a response inside the muscle cell. [4]

4 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 ρ-TIA binds to the receptors on the muscle cells preventing the flow of calcium ions into the muscle cells, rendering them ineffective. To investigate the effects of conotoxins, ρ-TIA protein was administered on zebrafish to evaluate the escape response of the fish. Details of the study includes: ● the use of four groups of zebrafish labelled groups 1 to 4 ● group 1 zebrafish was administered with different concentrations of unmodified ρ-TIA protein ● groups 2 to 4 were each administered with different concentrations of modified ρ-TIA protein, where each group was given ρ-TIA protein with different amino acid sequences deleted ● the escape response of zebrafish were then recorded where a higher score corresponded to a higher chance of escape. Fig. 1.2 shows the results of the study. Fig. 1.2 (d) (i) Describe the effect of unmodified ρ -TIA on the escape response of zebrafish. [1] 0 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 escape response score concentration of ρ-TIA / M Group 1 Group 2 Group 3 Group 4 1x10-7 1x10-9 1x10-6 1x10-8 1x10-5

5 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 (ii) Explain which deletion in the modified -TIA has the greatest impact on its function. [4] (iii) Conotoxins are used to develop potential drugs for humans. These drugs can be tested on zebrafish that are good model organisms since they share 70 percent of their genes with humans. Suggest why zebrafish is used. [2]

6 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 Marine cone snails are found in tropical marine environments and are particularly prominent around coral reefs and other shallow-water tropical marine habitats. A single coral reef may have over 30 different species of Conus. Fig 1.3 shows: (a) the distribution of three common species of cone snails, C. tulipa, C. geographus and C. kinoshitai, which are endemic to the Philippine islands (b) the annual temperature range of the waters around the Philippine islands (c) shells of some cone snails collected around the Philippine islands. Fig 1.3(a) Fig 1.3(b) Fig. 1.3(c) 25.0 26.0 27.0 28.0 29.0 30.0 31.0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Minimum Maximum temperature / oC

7 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 (e) With reference to Fig. 1.3, (i) suggest reasons for the high number of species found at the coral reefs. [2] (ii) describe and explain the predicted effect of global warming on the distribution of cone snails within the Philippines. [4] (iii) identify one challenge of using morphology to classify cone snails. [1]

8 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 Fig. 1.4 shows the nucleotide base sequences of a length of DNA from the gene coding for cytochrome protein in six of the closely-related cone snail species found in the Philippine islands. Conus geographus A - - - - - - - - - - - - - T C T G G A Conus abbreviatus G - - - - - - - - - - - - A T C T G G C Conus ammiralis G A C A T G G T A T A T G A T C T G G G Conus catus T A C A T G G A A T A T G A T C T G G A Conus auricomus C - - A T G G T A T A T G A T C T G G G Conus distans A A C G T G G A A T G T G A T C C G G A Fig. 1.4 (f) (i) Suggest why it is useful to include gaps as indicated by dashes in Fig. 1.4 when aligning the nucleotide sequences. [1] (f) (ii) Explain what conclusions can be drawn from the data in Fig. 1.4. [3] (iii) Explain why there is insufficient evidence from Fig. 1.4 to draw conclusions about the evolutionary relationships between cone snails. [2] [Total: 30]

9 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 QUESTION 2 Fig. 2.1 shows the terminal differentiation of different cell types derived from a pituitary stem cell. Fig. 2.1 (a) State and explain the potency of the pituitary stem cell in Fig. 2.1. [2]

10 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 Human growth hormone (hGH) is a peptide hormone that has important roles in growth during childhood. Children who do not produce enough hGH are described as hGH -deficient and grow slower than other children. Current treatment involves daily injections of hGH to increase growth rate. An alternative treatment still being researched on is