2022 HCI JC2 H2 Biology Prelims Paper 3 MS

HWA CHONG INSTITUTION / 2021-2022 H2 BIOLOGY / Preliminary Examination Paper 3 / MS 1 HWA CHONG INSTITUTION (COLLEGE SECTION) 2022 JC2 9744 H2 BIOLOGY PRELIMINARY EXAMINATIONS PAPER 3 MARK SCHEME QUESTION 1 (a) Suggest and explain which hunting method is more efficient. [3] 1 *NE method; Any 2: 2 Ref to increased quantity of prey caught /eaten / AW; 3 Ref to conserving energy by not using additional energy for electrical discharge; 4 AVP ; 5 *TT method; Any 2: 6 Ref combination of both electrical and chemical methods to increase effectiveness in immobilising prey; 7 Ref to electrical discharge causing immediate immobilisation of prey; 8 Ref to more effective since direct injection of toxin/ electrical signal into prey; 9 AVP ; (b) Suggest how a cocktail of proteins instead of a single protein is advantageous for the cone snail. [3] 1 (specificity) Ref. to conotoxins having a specific complementary 3D conformations / complementary to a membrane bound receptor; 2 (variety) Ref to higher chance of binding to a receptor/ increase variety of membrane bound receptors that conotoxins can bind to; 3 (effectiveness) Ref. to, conotoxins targeting different prey / many different types of cells in one prey thus increasing success of capturing killing prey ; 4 Single toxin may lead to development of resistance in fish; 5 AVP ; (c) Describe how insulin is able to trigger a response inside the muscle cell. [4] 1 Binding of insulin to RTK triggers aggregation, and dimerization of RTK ; 2 Ref to autophosphorylation/ cross phosphorylation/ phosphorylation of tyrosine residues; 3 Cytoplasmic relay proteins bind and get activated triggering signal transduction pathways / Activated relay proteins acts on downstream proteins and activates them ; 4 Ref to correct description of one cellular response ; - GLUT4 channels / glucose transporters added to cell membranes increasing glucose uptake into cells - Increased use of glucose in respiration / increased rate of glycolysis - increases conversion glucose to glycogen / glycogenesis - Amino acid absorption/ protein synthesis / lipogenesis;

HWA CHONG INSTITUTION / 2021-2022 H2 BIOLOGY / Preliminary Examination Paper 3 / MS 2 (d) (i) Describe the effect of unmodified ρ-TIA on the escape response of zebrafish. [1] As concentration of ρ-TIA increased from 4x10-9 to 5x10-6M, escape response of zebrafish decreased gradually from 9 to 2 (A: lower limit range as values between 2 to 3); (d) (ii) Explain which deletion in the modified ρ-TIA has the greatest impact on its function. [4] 1 *Group 3 ; 2 Quote effect of ρ-TIA on escape response: ie: Increase of modified ρ -TIA from 5 x10 -9M to 1x10 -6M resulted in a reduction of escape response score of 9 to 8 ; R: comparison between gro